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Session Schedule & Abstracts

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Friday 1st July, 2016

Poster session & reception 2

Room: Grand Foyer   4:30 pm–6:30 pm

Geometric Morphometrics (GMM)
POS2-2  4:30 pm  Geometric Morphometrics reveals morphospaces for early and late shark embryos (Chondrichthyes, Elasmobranchii). Fritz K*, Department of Palaeontology, University of Vienna, Geozentrum, UZA 2, Althanstrasse 14, 1090 Vienna, Austria; Abed-Navandi D, Haus des Meeres - Aqua Terra Zoo GmbH, Fritz-Grünbaum-Platz 1, 1060 Vienna, Austria; Sato K, Okinawa Churaumi Aquarium, 424 Ishikawa, Motobu, Kunigami District, Okinawa Prefecture 905-0206, Japan; Tanaka S, Tokai University, 2-28-4 Tomigaya, Shibuya, Tokyo 151-0063, Japan; Kriwet J, Department of Palaeontology, University of Vienna, Geozentrum, UZA 2, Althanstrasse 14, 1090 Vienna, Austria
Abstract: Modern sharks can be divided into two clades. The Squalomorphii, comprising five orders such as the Squaliformes and the Galeomorphii, including orders such as the Orectolobiformes or the Carcharhiniformes. There is little known about the embryonic development in modern sharks, as these relatively large predators are often migratory and can hardly be held and bred in captivity. Geometric Morphometrics (GM) is an appropriate tool for investigating specimens of different sizes and ontogenetic stages, respectively. Here various developmental stages of three different shark species, Chiloscyllium punctatum, Galeocerdo cuvier and Chlamydoselachus anguineus were investigated using GM. Previous studies showed that the overall adult morphology is already established in stage 30 when approximately 37% of the embryonic development are completed. All specimens at this stage or older occupy three different morphospaces, revealed by a principal component analysis based on 15 homologous landmarks. The bottom dwelling bamboo sharks have a relatively ample morphospace, which indicates a high variability in their developmental trajectories. The tiger sharks display the very commonly known torpedo-like body shape, whereas the frilled sharks exhibit a more eel-like morphology. Both exhibit a very narrow morphospace, which portends a rather directional developmental trajectory. Early embryonic stages, conversely, seemingly occupy different morphospaces, demonstrating massive shape changes through which all the species go during their development. This indicates that two morphospaces for each species exist, one for the early and one for the late embryos. It was not possible to identify a phylotypic period, indicating that development in these three species might diverge very early. Further studies, however, incorporating additional species, specimens, and also metric measurements are necessary for support of this assumption.

POS2-4  4:30 pm  Phylogenies from shapes: using shell landmarks to infer the phylogeny of geoemydid turtles. Ascarrunz E*, University of Fribourg, Switzerland
Abstract: Morphology is an important source of phylogenetic markers, but the complex nature of phenotypes creates major methodological challenges for estimating phylogenies. The field of geometric morphometrics has had great success in the analysis of biological form based on landmark coordinates to address problems of intra- and interspecific variation. However, the use of landmark data for phylogenetic inference has been limited and historically contentious. A series of recent studies has succeeded in finding significant phylogenetic signal in landmark coordinate data, allowing for a more optimistic outlook. Here, I explore the use of this kind of data for the inference of the phylogeny of geoemydids, a species-rich clade of cryptodiran turtles. The relationships between the species of this group have proven particularly difficult to estimate with both molecular sequences and matrices of traditional discrete-state morphological characters. The meshes formed by the sutures and the scute sulci on the bony carapace of turtles are particularly convenient for the placement of type I landmarks. I defined 76 such landmarks for each side of the shell, and digitised them in a 3D space with a microscribe. The sample includes over 130 specimens, representing over 57 percent of all the geoemydid species plus testudinid and emydid species as outgroups. In the present contribution, I assess the potential of these data for phylogenetic analysis by comparing the results and performance under alternative methods, and I discuss some general challenges.

POS2-6  4:30 pm  Sources of shape change in the testudine skull: A 3D geometric morphometric analysis. Croghan J*, Ohio University
Abstract: The breadth and diversity of testudine head shapes are hypothesized to reflect aspects of ecology and behavior. In order to investigate the evolutionary and functional links between feeding behavior and the morphology of the feeding apparatus of testudines, we performed the first landmark-based 3D geometric morphometric analysis of testudine crania. Virtual 3D models were produced from CT scans of 24 species representing the breadth of families, diets, and feeding modes present in turtles and tortoises. Landmark data were collected using the auto3dgm package in the statistical program R and analysis was performed in Geomorph. Species in the principal components (PC) analyses were labeled with their dietary, feeding mode, habitat, or phylogenetic affinities to assess potential associations with patterns of shape change. The only variable that produced a clear pattern was diet. Nearly all species with a carnivorous diet plotted on the positive side of PC1 (explaining 30% of the variation), while herbivorous and omnivorous species were grouped on the negative end of PC1. No clear dietary pattern is associated with PC2 (22%) or PC3 (13%) in this sample. Shape change towards the positive extreme of PC1 primarily involves an increase in head width relative to head length, but there are also conspicuous rotations in the aspects of the mandibular condyle (to face more medially) and the trochlear process (to face more laterally). PC2 appears to increases the ratio of head height to head length toward the positive extreme, while the positive extreme of PC3 reflects an increase in the depth of the supraoccipital crest and a relative anterior-posterior shortening of the adductor chamber. In addition to confirming previous findings that overall head width and head height vary predictably with diet, this study has also uncovered new sources of variation in anatomical details that were previously unexamined.

POS2-8  4:30 pm  The influence of phylogeny and diet in the skull morphology of representatives of Dipsadidae (Squamata: Serpentes). Murta-Fonseca R.A.*, Museu Nacional, Universidade Federal do Rio de Janeiro; Fernandes D.S., Instituto de Biologia, Universidade Federal do Rio de Janeiro
Abstract: Body form can be attributed to adaptation to the environment by natural selection, but can also be a result of strong phylogenetic inertia. Skull morphology in snakes provides critical information on the evolution of some morphological complexes. The family Dipsadidae includes representatives with a large diversity of forms, habits, and diet. We aim to explore the evolution of skull morphology within the family Dipsadidae through geometric morphometrics (GM) and to verify the existence of skull forms with morphological syndromes associated to certain diets. We performed GM analyses using the dorsal view of 70 species of the family and 37 landmarks. The PCA showed discrimination between the subfamilies Xenodontinae and Dipsadinae, despite having some overlap; some tribes were recovered, although showing a large overlap of patterns, except for Dipsadini and Elapomorphini (well discriminated); all diet categories were weakly discriminated. PC1 reflects mostly the width of the skull and proportion of the bones. PC2 reflects mainly width and length of the skull and length/position of supratemporals. The CVA concerning the tribes showed the groups well discriminated, with an overlap of patterns between Xenodontini, Philodryadini and taxa considered as incertae sedis—CV1 reflects mostly the proportion of braincase bones while CV2 reflects mostly the width of the skull. CVA concerning diet also showed well discriminated groups, with a complete overlap related only to species which feed on lizards and anurans—CV1 shows changes in the width of skull and proportion of braincase bones; CV2 reflects the width and length of skull and proportions of all bones, except for supratemporals. Snakes feeding on a wide variety of vertebrates have wider skulls, corroborating previous works. These results indicate that both phylogeny and diet are reflected in the skull morphology of such snakes, showing the importance of feeding habits in the evolution of the skull.

POS2-10  4:30 pm  Beak shape is a poor predictor of trophic ecology in extant birds. Navalón G.*, School of Earth Sciences, Life Sciences Building, University of Bristol; Marugán-Lobón J., Unidad de Paleontología, Facultad de Ciencias, Universidad Autónoma de Madrid; Bright J.A., Department of Animal and Plant Sciences, Alfred Denny Building, University of Sheffield; Rayfield E.J., School of Earth Sciences, Life Sciences Building, University of Bristol
Abstract: Beak shape is a textbook example of trophic adaptation in bird biology and of diversification in evolutionary theory. In spite of numerous qualitative studies linking beak shape and trophic ecology, a quantitative, phylogenetically-comprehensive study of beak ecomorphology is still lacking. Using geometric morphometrics, we digitized beak shape of a 176 extant birds (38 orders, 96 families) in lateral view and statistically tested the association between beak morphology and trophic ecology. On the same sample we calculated the mechanical advantage (MA) of the main adductor muscles of the skull for each species. Surprisingly, we found that neither beak shape nor MA are good predictors of trophic ecology in birds. 80% of the studied species show low MA values within a narrow range, implying that in most birds the beak is employed as a fast gape/low force mechanism. Clades utilizing pre-swallowing mechanical processing of food items are best categorized by the interplay between shape and MA, showing two very morphofunctional solutions; cracking/biting herbivorous birds, particularly parrots, exhibit deep and curved beaks along with the highest values of MA (enhanced bite force/slow gape speed), exploring more than the upper half of the total range of values. By contrast, the three main clades of raptorial birds exhibit deep, curved beaks with relatively low MA values. The absence of an enhanced bite force in these avian clades is surprising, and implies that more research is necessary to understand if and how birds rely on alternative strategies for feeding. Given the extreme multifunctional nature of the avian beak, it is plausible that non-trophic selective pressures might be underlying in its macroevolution, thus impeding a finer match between trophic ecology, bill shape, and mechanical performance in birds.

POS2-12  4:30 pm  Growth orientations of rhamphothecae in extant beaked animals with implications to the reconstruction of the beaks in extinct taxa. Urano Y*, Department of Earth and Environmental Sciences, Nagoya University; Matsumoto R, Kanagawa Prefectural Museum of Natural History; Kawabe S, Gifu Prefectural Museum; Tanoue K, Fukuoka University; Ohashi T, Kitakyushu Museum of Natural History & Human History; Fujiwara S, Nagoya University Museum
Abstract: The beaked rostra evolved in many lineages of tetrapods, including turtles (Testudinata) and birds (Aves), accompanied by the loss of their teeth. The beaks of these extinct taxa were possibly covered by keratinous rhamphothecae in those of the extant turtles and birds. To reveal the evolution of the designs and functions of the jaw apparatus among tetrapods, more accurate reconstruction of the entire shape of the beak is required for each extinct taxon. However, reconstruction of the shape of the rhamphotheca, which is rarely preserved in fossils, remains difficult because the relationship between the shape of the rostral bone and the thickness/growth orientation of the overlying rhamphotheca is yet to be understood. We CT-scanned upper jaws of more than 70 extant beaked tetrapod specimens (Aves: 41 genera, 28 families; Testudinata: 16 genera, 10 families), and compared the shape of the rostral bone and the overlying rhamphotheca. The rhamphotheca occupied 16.6–71.6% of the entire volume of the beak, and did not cover the rostral bone uniformly in thickness. The results imply that estimation of the rhamphotheca volume or the thickness in fossil specimens remains a challenging topic. However, the following features were found for the rhamphotheca growth orientations among the studied specimens, regardless of the beak shape. (1) The thickness of the rhamphotheca was emphasized distal to the distal-most local maximum point of the width or depth of the rostral bone. (2) The rhamphotheca grew distally along the distal-most curvature of the culminal margin of the rostral bone. The abovementioned morphological relationship between the bone and the rhamphotheca will be one of proxies for reconstructing the entire shape of the beak in extinct taxa.

POS2-14  4:30 pm  Novel analyses estimating evolutionary rates using ancestral state reconstruction suggest recent stasis in the cranium of the dwarf lemur Cheirogaleus (Primates: Cheirogaleidae). Fulwood EL*, Duke University; Cunningham CW, Duke University; Boyer DM, Duke University; Groeneveld LF, University of Gottingen
Abstract: The Darwin is a rate unit of evolutionary change. Application to the fossil record requires a relatively complete stratigraphic column to infer ancestor/descendant relationships, however. In lieu of direct information on ancestral species, there are now methodologies for estimating character state values at the internal nodes of a lineage using values from tip taxa and a phylogenetic tree. We utilize ancestral state reconstruction in the calculation of rates in Darwins and propose this novel protocol as a means of investigating evolutionary pattern in recently diverging taxa. We obtained craniodental measures and genetic samples from 42 individuals of Cheirogaleus from an earlier study. Craniodental measures were regressed against geometric mean and the residuals reduced to three principle components. A population tree was inferred using mitochondrial sequences. ML ancestral state reconstructions were performed using each PC and the geomean as continuous traits. Darwins were calculated as the log difference between the values at each node or tip and its adjacent, ancestral node, divided by the intervening branch length. Under directional evolution, the best-fit line relating Darwins to branch length should have a slope of 0. Under stasis, it should have a slope of -1. Intermediate values fit the null expectation of a random-walk. Slopes of Darwins against branch lengths were tested for significant difference from slopes of 0 and -1 using a 0.95 confidence interval. PC1, PC2, and PC3 of the genus; PC1, PC2, and the geomean of C. medius; and PC1, PC2, and PC3 of C. major show slopes significantly different from 0 and not from -1. PC2 of C. crossleyi shows a slope significantly different from -1 but not from 0. All other slopes were consistent with a random walk. This suggests a preponderance of stasis in the recent evolution of the cranium of dwarf lemurs except in C. crossleyi, which shows some evidence of directional evolution.

POS2-16  4:30 pm  Comparative shape analysis of koalas and wombats. Mehari Abraha H*, Moving Morphology and Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland, Australia; Weisbecker V, School of Biological Sciences, The University of Queensland, Australia; Terhune C.E, Department of Anthropology, University of Arkansas, USA; Morrison R.E, Moving Morphology and Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland, Australia; Wailan M.A, Moving Morphology and Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland, Australia; Mullins C.M, Moving Morphology and Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland, Australia; Sharp A, School of Science & Technology, University of New England, Australia; Johnston S, School of Agricultural and Food Sciences, The University of Queensland, Australia.; Panagiotopoulou O, Moving Morphology and Functional Mechanics Laboratory, School of Biomedical Sciences, The University of Queensland, Australia
Abstract: Extant vombatiform marsupials (koalas and wombats) are the only survivors of an extensive radiation of mostly terrestrial vombatiforms dating back to the late Oligocene. This mammalian “megafauna” ranged in size from the ~6 kg koalas alive today to the 3000 kg Diprotodon optatum and exhibited a wide variety of skull shapes and sizes to exploit different ecological niches. Extant wombats and koalas are highly adapted for either grazing or browsing, respectively. Within wombats, the northern hairy-nosed wombat (NHNW) and common wombat live in moister habitats and vegetation than the southern hairy-nosed wombat (SHNW), which is confined to an arid environment. Nearly all extinct vombatiforms are expected to have been fallen along the dietary spectrum delimited by the koala and wombat. This study defined the morphological change along this spectrum, and looked for finer cranial adaptations among wombats, using Procrustes-based three-dimensional geometric morphometrics. Principal components analysis of 54 landmarks on skull shapes of koalas (n=10), northern (n=30)/southern (n=12) hairy-nosed wombats, and common wombat (n=6) showed that most of the variation in the dataset (PC1; 65%) relates to wombat/koala differences. As expected for a browser, 3D warp visualizations show that koalas have shorter, pincer-like snouts, and less procumbent teeth, than wombats. Wombats mostly differ from each other along PC2; surprisingly, SHNWs are intermediate between NHNWs and common wombats. This is unexpected because NHNW and common wombats are more similar both in range and, at least historically, in having a moister habitat and higher water-content in their diet. It is possible that phylogenetic signal outweighs ecological adaptation in the wombat species, with the common wombat closer to the ancestral state; extrapolations of feeding type might therefore be best restricted to the grazer/browser dichotomy between koalas and wombats. Funding: The Wombat Foundation, Australia

POS2-18  4:30 pm  Analyzing the association between platyrrhine locomotor mode percentages and talar shape. Püschel TA*, University of Manchester; Sellers WI, University of Manchester
Abstract: Locomotor mode percentages (LMPs) (i.e. the time percentage a species spend performing a certain locomotor behavior) and talar morphology were assessed to investigate if there is a relationship between locomotor behavior and talar shape. The LMPs of 31 platyrrhine species were obtained from the literature. These values were log-transformed to perform a PCA in order to visualize locomotor affinities (explained variance: PC1 54.27% and PC2 25.23%). Furthermore, the 3D surface models of 22 platyrrhine species downloaded from online databases were analyzed using geometric morphometrics to understand morphological affinities. A principal component analysis (PCA) of the Procrustes coordinates was carried out and a phylogeny was projected onto the two first dimensions to display most of the morphological variation (explained variance: PC1 30.98% and PC2 13.03%), while showing the evolutionary relationships between the analyzed taxa. A partial least squares analysis was performed to examine the association between shape variables and log-transformed LMPs in 15 species present in both datasets. The obtained results show that there is a significant association between talar morphology and the time percentage that different species spend performing dissimilar locomotor behaviors (RV-coefficient: 0.63; p-value: <0.0001; 10,000 permutations). These results contribute to understand the relationship between talar morphology and LMPs, thus providing an important tool to reconstruct the possible locomotor repertoires of extinct species and to appreciate the locomotor diversity observed in extant platyrrhines. Grant sponsor: Becas Chile Scholarship Program, CONICYT, Chile.

POS2-20  4:30 pm  Musculoskeletal fitness in small mammals: are captive-bred individuals fit for the wild? Foreman C, School of Animal and Veterinary Sciences, The University of Adelaide; Stott PG, School of Veterinary Medicine, City University of Hong Kong; Norris RM*, School of Animal and Veterinary Sciences, The University of Adelaide
Abstract: Many attempts at reintroducing captive-bred mammals, with the aim of preserving biodiversity, are unsuccessful with causes being attributable to cognitive inability to recognise predators, lack of normal social behaviours and failure to thrive due to poor ability to find food, water and shelter. Animals for reintroduction are typically reared under spatially constrictive conditions compared with their wild counterparts yet very few studies have tested musculoskeletal fitness as a factor for reintroduction to the wild. The European hare (Lepus europeaus) provides a sensitive model for such a study as its survival is dependent on its extreme athleticism in the wild to escape predation by the fox (Vulpes vulpes). Due to the finely balanced sensitive nature of predator-prey relationships, this study assumed that any changes in morphology in captive-reared animals that deviate even slightly from wild-type would have diminished survival probability. The aim being to determine whether rearing animals in spatially restrictive environments had a significant impact upon the musculoskeletal system of the animal which could ultimately diminish survival probability. Two populations of hares (wild-caught (N=21) and captive-bred (N=24) were sampled. The proximal femur was chosen for shape change analysis due to its importance in providing anchorage for major locomotor musculature. Landmarks were selected and measured in three dimensions and analysed using geometric morphometrics. Hares raised under confined conditions showed marked shape changes in the proximal femur (notably a proximal shift in the lesser trochanter and quadratus femoris attachment site; a shorter femoral head/neck; a reduced greater trochanter). These changes occurred at sites of major musculature attachment resulting in reduced stride length and hind limb manoeuvrability whilst running. Therefore, these animals lacked the musculoskeletal fitness for release into the wild.

POS2-22  4:30 pm  Reconstruction of muscle fascicle architecture from digital images: a combined texture mapping and streamline approach. Stark H*, Friedrich-Schiller-University Jena; Mundry R, Max Planck Institute for Evolutionary Anthropology, Leipzig; Neininger F, Universität Stuttgart; Heidlauf T, Universität Stuttgart; Röhrle O, Universität Stuttgart; Kupczik K, Max Planck Institute for Evolutionary Anthropology, Leipzig
Abstract: Skeletal muscle models are used for a better understanding of movement and force generation in both biological and bioengineering research. Yet, they often lack a realistic representation of the muscle's internal architecture, which is primarily composed of muscle fibre bundles, known as fascicles. Here, we present a reconstruction method of the fascicular spatial arrangement and geometry of an exemplary facial muscle, based on a combination of pattern recognition and streamline computation. From our preprocessed µCT-data and based on a pattern recognition algorithm, which represents the fascicle directions, a vector field was created. The pattern recognition algorithm uses the different statistical gray value distributions along or across the fascicles to find their main direction. After this, the resulting vector field was transformed into a realistic muscle fascicle representation based on a streamline approach. We conclude that the presented approach allows for implementing realistic fascicle information into finite element models of skeletal muscles for a better understanding of the function of the musculoskeletal system. Additionally, it can be used to analyse intraspecific or interspecific muscle architectures.

Feeding (FED)
POS2-24  4:30 pm  Measuring bite force in the domestic dog (Canis lupus f. familiaris): A novel experimental approach for recording predatory bites in vivo. Bemmann MV*, Max Planck Institute for Evolutionary Anthropology; Helbig T, Technische Universität Ilmenau; Kupczik K, Max Planck Institute for Evolutionary Anthropology
Abstract: Bite force is an important ecological variable that is related to vertebrate feeding and social behavior. Although bite force is known to change with behavior (e.g. prey capture, ingestion.), it is difficult to gain accurate measurements for these different behaviors. Here we present in-vivo bite force data taken with a new measurement system designed for domestic dogs, which are an ideal model for studying biting performance given their large diversity in body size and skull form. To this end, load cells were integrated into a protection biting sleeve and so changes in bite force over time were recorded. We gathered bite force data from 14 mixed sex, adult, trained German shepherd dogs ranging in age from 0.7 - 9 years. Body mass and wither height were collected to determine if either was correlated to bite force. We measured bite force for two predatory behaviors (short distance biting from a seated position and biting after running a distance of 10 meters) using the sensorized biting sleeve worn by a dog handler. Values were estimated in a 5 second window after biting began. Results yielded a maximum bite force (MBF) of 905 ± 249 for the seated bite and 967 ± 231 N for the running bite. Dogs tended to reach their MBF within the first 2 seconds of biting followed by a decrease over time. Bite forces showed an oscillatory pattern, indicating no constant bite force was reached. This could be due to the dogs’ training, or an instinctive predatory behavior. Contrary to previous studies, neither sex nor body mass was correlated to MBF (p < 0.05), although there was a trend towards increasing MBF with increasing body mass and wither height. Following this promising pilot study we now aim to apply this measurement system to a larger range of dog breeds.

POS2-26  4:30 pm  Biting mechanics of raccoons (Carnivora: Procyon lotor) and skunks (Carnivora: Mephitis mephitis): exploring the link between cranial morphology and infectious disease control. Klimovich CM*, Ohio University; Williams SH, Ohio University
Abstract: Oral rabies vaccination (ORV) programs in North America have historically been effective in controlling the spread of rabies in carnivoran populations. This is accomplished by distributing baits filled with the rabies vaccine that are located and consumed by wild animals. This has been most effective in raccoon populations which show significantly reduced rabies infections. However, despite also being a major rabies vector, the striped skunk has a significantly lower inoculation rate in wild populations although the vaccine has been shown to be effective in captive studies. Here, we aim to elucidate biomechanical differences between skunks and raccoons that may contribute to differences in oral immunization success. 3D biomechanical models incorporating data from the jaw muscles were developed to estimate bite forces and muscle moments at different gapes for the two species. Results demonstrate differences that might impact their ability to break down the baits to access the vaccine. Data from this project may be used to improve bait design and manufacturing.

POS2-28  4:30 pm  The evolution of insectivory in freshwater stingrays. Kolmann MA*, University of Toronto Scarborough; Welch KC, University of Toronto Scarborough; Summers AP, University of Washington; Lovejoy NR, University of Toronto Scarborough
Abstract: Stingrays have diversified to fill numerous trophic niches across freshwater, estuarine, and marine habitats, despite lacking the suite of feeding mechanisms (i.e. pharyngeal jaws) that underlie similar ecomorphological plasticity in teleosts. Notable among examples of such diversity are the freshwater rays of South America. From an estuarine, dietary generalist ancestor, these rays have evolved to specialize on prey such as mollusks, fishes, crustaceans, and even insects – the only extant insectivorous elasmobranchs. We analyzed data characterizing prey processing in an insectivorous freshwater ray (Potamotrygon motoro) presented with prey of increasing toughness proportional to the amount of chitin in its exoskeleton. Asymmetrical jaw protrusion and symphyseal flexion of the jaws are typical of feeding on tougher prey items like insects. Insectivorous rays can behaviorally reorient their teeth from flattened occlusion to occluding cusps when feeding on tough prey, as the dental ligament is contracted. Despite a deceptively simple jaw architecture these fishes accomplish impressive post-capture prey manipulation and processing by combining hydrodynamic forces with complex movements of the jaws.

POS2-30  4:30 pm  Strange from the start: Ontogeny of the filtering mechanism in Silver Carp. Cohen K*, George Washington University; Hernandez LP, George Washington University
Abstract: Highly invasive Asian carp are destroying ecosystems throughout the United States by outcompeting native species. With populations growing at an alarming rate, these fish have proven difficult to control. Their ability to thrive within eutrophic environments is due to their very efficient filter-feeding mechanism. Here we present data from an ontogenetic series of Silver Carp ranging in size from 15-400mm SL detailing how this unique filtering structure is built. Like many filter-feeding species, Silver carp possess an incredibly large epibranchial organ that occupies the majority of the dorsal buccal cavity. Branchial arches 1-4 have greatly modified gill rakers that span both the ceratobranchial ventrally and the epibranchial as it curves into the body of the epibranchial organ. From the earliest ontogenetic stage examined individual gill rakers already show a modified shape as compared to the basal character state for Cypriniformes. As development proceeds the structure of these gill rakers becomes increasingly complex. By early juvenile stages secondary growth of bone stitches together the primary gill rakers, forming a screen-like mesh upon which future elaborations of the filtering structures are built. As development proceeds the original shape of the gill rakers is modified, regressing in height only later to become scaffolding for more complex filtering structures. Gill rakers involved in filtering undergo significant architectural changes during development, while those curling into the epibranchial organ remain largely unchanged from earlier ontogenetic stages. Comparisons with the Bighead carp, a congeneric, suggest that the basal cypriniform morphology is retained within Bigheads.

POS2-32  4:30 pm  The role of the chondrocranium and sutures in a biomechanical model of Tupinambis (Lepidosauria). Jones M.E.H., School of Earth and Environmental Sciences, The University of Adelaide, North Terrace, Adelaide, South Australia, 5005, Australia; Groening F., School of Medicine and Dentistry, University of Aberdeen, Aberdeen, AB25 3BZ, UK; Crumpton N.*, Research Department of Cell and Developmental Biology, Anatomy Building, UCL, University College London, Gower Street, London, WCIE 6BT, UK; Fagan M.J., School of Engineering, Medical and Biological Engineering Research Group, University of Hull, Hull, HU6 7RX, UK; Evans S.E., Research Department of Cell and Developmental Biology, Anatomy Building, UCL, University College London, Gower Street, London, WCIE 6BT, UK
Abstract: Lizards and tuatara are ideal taxa for investigating the evolution of skull mechanics as they exhibit a wide range of skull shapes, feeding behaviours and lifestyles. Due to recent advances in visualization and modelling software, such research can now be undertaken using complex computer-based simulations. However, the role of soft-tissue structures such as cranial sutures, which are known to vary considerably in structure amongst lepidosaurs, remain poorly understood. To date, biomechanical models of Uromastyx and Sphenodon suggest that cranial sutures redistribute strain rather than simply dampening it, but wider comparisons are necessary. We investigate lepidosaur sutures in the South American tegu lizard (Tupinambis) and for the first time include another 'soft-tissue' component, the chondrocranium: the cartilaginous part of the braincase that lies along the mid-sagittal plane between the rostrum and ossified posterior braincase. Micro-computed X-ray tomography (microCT) was used to build an accurate 3D model of the skull with sutures, and a representation of the chondrocranium. Detailed dissection was used to construct a representation of the muscles and multi-body dynamics analysis (MDA) was used to predict the forces acting on the skull during various biting conditions. Finally, finite element analysis was used to reveal the resultant strain distributions through the skull and the influence of the soft tissue structures. Our analyses show that including the cranial sutures has a far greater effect on strain distribution than inclusion of the chondrocranium. As in previous studies, the presence of the sutures increases overall skull strain but reduces areas of peak strain. This result is consistent with an even-strain distribution necessary for appropriate growth and bone turnover. By contrast, the chondrocranium made little difference to the strain within the cranial bones despite various adjustments to its shape and material properties.

POS2-34  4:30 pm  Functional aspects of the interpterygoid vacuities in the palate of early tetrapods and a reconstruction of the associated cranial muscles. Witzmann F, Department of Ecology and Evolutionary Biology, Brown University, USA; Lautenschlager S, School of Earth Sciences, University of Bristol, United Kingdom; Werneburg I*, Senckenberg Center for Human Evolution and Palaeoenvironment (HEP) at Eberhard Karls Universität, Germany
Abstract: A diagnostic feature of temnospondyls is the presence of an open palate with large interpterygoid vacuities, unlike the closed palate of most other early tetrapods and their fish-like relatives, in which the vacuities are either slit-like or completely absent. Attachment sites on neurocranium and palatal bones in temnospondyls allow the reconstruction of a powerful m. retractor bulbi and a large, sheet-like m. levator bulbi that formed the elastic floor of the orbit. This muscle arrangement indicates that temnospondyls were able to retract the eyeballs through the interpterygoid vacuities into the buccal cavity, like extant frogs and salamanders. In contrast, attachment sites on palate and neurocranium suggest a rather sauropsid-like arrangement of these eye muscles in stem-tetrapods and stem-amniotes. However, the anteriorly enlarged, huge interpterygoid vacuities of long-snouted stereospondyls suggest that eye retraction was not the only function of the vacuities here, since the eye-muscles filled only the posterior part of the interpterygoid vacuities. We propose an association of the vacuities in stereospondyls with a long, preorbital part of the m. adductor mandibulae internus (AMIa). The trochlea-like, anterior edge of the adductor chamber suggests that a tendon the AMIa was redirected in an anteromedial direction in the preorbital skull and dorsal to the pterygoids. This tendon then unfolded into a wide aponeurosis bearing the flattened AMIa that filled almost the complete interpterygoid vacuities anterior to the orbits and was medially and laterally attached to the margins of the interpterygoid vacuities and dorsally to the skull roof. To test the possibility that the interpterygoid vacuities served for stress distribution during contraction of the AMIa, we conducted different Finite Element Analyses in which an original stereospondyl skull and different theoretical models were considered in which the vacuities differ in size or are completely absent.

POS2-36  4:30 pm  Inferring the diets of pterosaurs and extant analogues using quantitative 3D textural analysis of tooth microwear . Bestwick J*, University of Leicester; Unwin DM, University of Leicester; Purnell MA, University of Leicester
Abstract: Pterosaurs were a successful group of flying reptiles, dominating the air for 150 million years during the Mesozoic. The ecology of pterosaurs has been widely debated, and a range of hypotheses concerning diet have been proposed, including insectivory, piscivory, carnivory and/or durophagy. Many of these hypotheses are based on comparisons between the shapes and structures of their teeth with those of extant organisms. This approach however is generally qualitative, and assumes that tooth form and function are closely linked and correlated with diet. A more robust method involves quantitative analysis of the 3D sub-micron scale textures of worn tooth surfaces—dental microwear texture analysis. Microwear is produced during feeding as abrading food items alter tooth surface textures. Material properties of food create different microwear characteristics; in general harder items create rougher surfaces. 3D textural analysis of microwear has proven useful in elucidating the properties of food for several extinct taxa, including early stem mammals, fishes and early whales, but the technique has never been applied to pterosaurs. This study tests the hypothesis that microwear patterns can be detected in non-occluding pterosaur teeth, and that microwear textures differ between pterosaur taxa with different diets. An important step in addressing these hypotheses is to validate pterosaur microwear analysis by examining microwear textures of extant organisms with known diets to provide a comparative data set. This has been achieved through analysis of non-occlusal microwear textures in extant bats and crocodilians, clades within which species exhibit a range of insectivorous, piscivorous and carnivorous dietary ecologies. Our results—the first test of the hypothesis that non-occlusal microwear textures in these extant organisms vary with known dietary differences—provide the context for the first robust quantitative tests of dietary ecology in pterosaurs.

POS2-38  4:30 pm  Morphology of the pterygoid musculature in pleurodire turtles. Ferreira GS*, Faculty of Philosophy, Science and Literature, University of São Paulo; Werneburg I, Senckenberg Center for Human Evolution and Palaeoenvironment (HEP) at Eberhard Karls Universität; Museum für Naturkunde - Leibniz-Institut für Evolutions- & Biodiversitätsforschung
Abstract: Among sauropsids, at least three parts of the jaw adductor musculature can be been identified. The musculus (m.) adductor mandibulae externus is the most prominent jaw adductor in turtles. Its fibers originate on the walls of the upper temporal fossa and insert to the coronoid process of the lower jaw mostly by the coronar aponeurosis. They are directed in rostral and ventral direction, exerting an adduction component when closing the jaw. M. adductor mandibulae posterior originates on the rostral surface of the quadrate on the otic chamber, runs ventrad, and inserts to the surangular of the lower jaw. This unit is closely associated to m. adductor mandibulae internus, although clearly separated from it by the mandibular ramus of the trigeminal nerve. The internal adductor is commonly separated into Partes pseudotemporalis et pterygoidei. The former originates on the vertical wall of the parietal and inserts to the articular of the lower jaw. The pterygoideus portion can be separated into three heads, the pterygoideus dorsalis et ventralis, whose fibres run caudad and ventrad from their origin on the dorsal and ventral surface of the pterygoid, and the pterygoideus posterior, which originates on the basisphenoid and on the ventral surface of the caudal part of the pterygoid. The pterygoideus fibers insert close to the jaw joint (articular-quadrate) and exert a protraction component on the movement of the lower jaw. In pleurodires, there are three specific skull structures affecting the unique arrangement of the pterygoideus structures, namely the processus trochlearis pterygoideus, the septum orbitotemporale, and, in Podocnemididae, the cavum pterygoideum. We focus on two taxa, Podocnemis unifilis and Phrynops geoffroanus, to reanalyze and compare the different arrangements of the pterygoideus structures in Pleurodira and their subsequent force components to protract and retract the lower jaw in detail. [Funding: FAPESP 2014/25379-5 to GSF]

General Morphology (GEN)
POS2-40  4:30 pm  Domestication effect on skull morphology and biting performance in rats. Becerra F*, Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max Planck Institute for Evolutionary Anthropology; Bemmann MV, Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max Planck Institute for Evolutionary Anthropology; Cagan A, Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Anthropology; Konoshenko M, Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences; Kozhemyakina R, Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences; Kupczik KF, Max Planck Weizmann Center for Integrative Archaeology and Anthropology, Max Planck Institute for Evolutionary Anthropology
Abstract: Domestication of wild animals has been a key factor in the development of human civilizations. It enabled the development of more suitable food resources, modes of transportation, companionship and even enhanced group defense against potential threats. This practice has resulted in a wide variety of breeding lines differentiated by their differences in morphology, physiology, gene expression and behavior. Here, in vivo incisor biting performance and skull morphology were tested in 4 months old male and female gray rats Rattus norvegicus, originating from two wild derived breeding lines selected for aggressive and tame behavior, respectively, towards humans for over 70 generations. We focused on the aggressive and intercross (aggressive*tame) lines, totaling 39 individuals. Body size, head length and mandibular width all showed clear sexual dimorphism, with males always being larger than equivalent females. Considering inter-line comparisons, no significant difference was found in any size measurement in either males or females, except for aggressive males having larger heads than intercross males. Contrary to the morphological data, within breeding lines females produced stronger bites than males, whilst aggressive females bit harder than the intercross females. However, no inter-line differences were found in males. Once the body size effect was removed, bite force was (poorly) predicted by mandibular width, and only in aggressive males. Thus, beyond their behavior, genetics and physiology, the long-term domestication process resulted in smaller head size in the least aggressive rats while overall body size remained relatively similar. Yet, our results on biting performance cannot be attributed to differences in body or head size. They might offer additional evidence of the dimorphic aggressive behavior in female rats associated with maternal care and social structure, which has been observed in gregarious wild rodents.

POS2-42  4:30 pm  Finite element analysis of maxillary alveolar bone in rats under dental occlusal changes. Prado FB*, Piracicaba Dental School - University of Campinas; Freire AR, Piracicaba Dental School - University of Campinas; Okamoto R, Araçatuba Dental School - Paulista State University; Rossi AC, Piracicaba Dental School - University of Campinas
Abstract: The dental occlusal plane can be changed during dentistry procedures. Premature contacts can result in changes in morphology alveolar bone, and consequently stimulate bone remodeling. The aim of this study was evaluated the equivalent von Mises strain at the interradicular septum of the upper first molar of rats under dental occlusal changes by finite element analysis. To develop the finite element model, the geometry condition were based on an experimental model, where the occlusal surface of molars in rats was changed by resin cementation. The rat head was scanned in microCT, in which the images presented thickness of sections (pixel size) of 30 µm. From these images, the 3D geometry was composed by skull and mandible structures, periodontal ligament and the teeth. In this step were obtained two geometries, one with normal dental occlusion (control) and one with a resin block bonded on the upper molars occlusal surface. The finite element analysis configuration was defined according the rat molar chewing. The mechanical properties values were assigned as linear elastic and isotropic. The mechanical properties used were to bone teeth (Young modulus: teeth (Young modulus: 19920 MPa/ Poisson coefficient: 0.3), teeth (Young modulus: 30000 MPa/ Poisson coefficient: 0.3) and periodontal ligament (Young modulus: 50 MPa/ Poisson coefficient: 0.4). To simulate the molar chewing, the masticatory force was 20 N. The force was applied in the long axis of each tooth. We evaluated the same side of the experimental condition. The results showed that the interradicular septum presented high micro-strain values in control model compared to the model with occlusal change. We concluded that the occlusal strain caused minor micro-strain in alveolar bone crest of the upper first molar.

POS2-44  4:30 pm  Feeding in Testudines: A finite element and parametric analysis of a tortoise skull. Luján A.H.*, Institut Català de Paleontologia M. Crusafont; Marcé-Nogué J., Centrum für Naturkunde - University of Hamburg; Delfino M., ICP-UNITO; Alba D.M., Institut Català de Paleontologia M. Crusafont; Fortuny J., ICP-MNHN
Abstract: In turtles, the adductor musculature in the skull is partly attached to the supraoccipital crest and, consequently, the latter plays a potential role in feeding behavior that largely remains unexplored. We performed a CT scan of an adult skull of an African spurred tortoise (Centrochelys sulcata) and, on its basis, we performed a 3D Finite Element Analysis (FEA), to test the biomechanical capabilities of this taxon during mastication and to understand its feeding ecology. We also performed a parametrical analysis of the length of the supraoccipital crest, enlarging and reducing its size. We generated several cases to test the efficiency of this structure under different feeding behaviors, so as to better understand its function as well as to determine the most likely selection pressures that determined its evolution. Our results show that, during loadings, most of the skull roof experiences no significant values of stress (particularly on the nasal area) or only low levels (around the orbital region). The highest values of stress are located in the anterior part of the crest and near the occipital condyles. Regarding the palate, significant stresses are mainly found near the posterior palatine foramen, while moderate stresses are found in the palate. Our parametric results reveal that enlarging the supraoccipital crest length increases of the stresses in the whole skull, but the potential bite force is only slightly increased and the mechanical advantage of enlarging this structure decreases. In contrast, if the crest is reduced or removed, the amount of stress mainly decreases, the bite force is almost equal to that in the original model, and the mechanical advantage increases. Overall, these results suggest that there should be a selection pressure toward maintaining (or even slightly decreasing) the length of the crest, whereas a further enlargement would not produce any obvious selective advantage from a biomechanical viewpoint.

POS2-46  4:30 pm  The utility of polymorphic characters in reconstructing the phylogeny of geoemydid turtles. Garbin RC*, University of Fribourg; Ascarrunz E, University of Fribourg
Abstract: Geoemydidae is a speciose clade of turtles with 69 species currently distributed in the tropical to temperate regions of Asia, Europe, North America, and South America. Although there have been several attempts to resolve the phylogeny of the group using morphology – the only method to reliably assess the completely unresolved fossil record of the group – unusually high levels of polymorphism and homoplasy have hindered this process, particularly as polymorphic characters were readily omitted thereby eliminating potentially useful phylogenetic information. A number of methods have been developed that allow coding polymorphic characters in phylogenetic reconstructions and it is our goal to explore the performance of these methods in tackling the phylogeny of geoemydids. The methods selected here to treat polymorphic characters after scoring were the 'majority method', 'frequency coding' and 'missing'. These methods were chosen because they recover a high phylogenetic signal and similar topology regardless of sample size. Of the 72 morphological characters analyzed for 307 specimens (representing 61 extant species of Geoemydidae), 70 characters were observed to be polymorphic and 24 show more than two character states. We expect that the use of polymorphic characters for reconstructing the phylogeny of geoemydid turtles will yield good results as previous studies have already shown that polymorphic characters can be an important source of phylogenetic information.

POS2-48  4:30 pm  Evolutionary associations between body shape and climate in tree frogs (Amphibia: Anura: Hylidae). Closel MB*, University of São Paulo ; Kohlsdorf T, University of São Paulo
Abstract: Variation of body size and shape can influence several aspects of individual’s morphology, physiology and ecology. Changes in size and/or shape are expected to affect surface-to-volume ratios (SVR) and, particularly for ectotherms, it can potentially affect thermal and water dynamics between the organism and its surrounding environment. The sensibility to environmental conditions might determine the distribution and diversity of these animals along different environments. Therefore, body shape can be a powerful predictor for detecting associations between species distribution patterns over different climates. This relationship can be investigated in a model with broad geographic distribution and morphological diversity, such as Hylidae treefrogs. SVR has been scarcely accessed, and discussions regarding species distribution usually do not incorporate this parameter and generalizes consequences about variation in size. As such, this work aimed to investigate patterns of variations in body shape in order to detect possible evolutionary associations with climate. Body shape was taken by conventional morphometrics and stereological SVR estimations and climatic parameters were extracted from (Hijmans et al., 2005). Analyses were conducted in R under a phylogenetic approach. Our results suggest that thinner smaller body shapes as well as increased SVR are associated with warmer climates. Additionally, species with increased SVR present relative narrow thermal niche width. Precipitation variables had no effects on body shape. As mostly anuran species are nocturnal and thermoregulatory behavior might be costly due to temperature effects on performance, temperature seems to plays major role setting limits in body shape. Thus, increased SVR coupled with thinner and smaller body shape might contribute in cooling down process in warmer climates, whereas low SVR combined with robustness shapes can represent a conservative shape for species distributed in colder climates. Funding: CAPES and FAPESP.

POS2-50  4:30 pm  Musculoskeletal development of the only matrotrophic viviparous anuran, Nimbaphrynoides occidentalis (Amphibia: Anura: Bufonidae). Penske S.*, Institut für Spezielle Zoologie und Evolutionsbiologie, Friedrich-Schiller-Universität Jena, Erbertstrasse 1, 07743 Jena, Germany; Mueller H., Institut für Spezielle Zoologie und Evolutionsbiologie, Friedrich-Schiller-Universität Jena, Erbertstrasse 1, 07743 Jena, Germany
Abstract: Viviparity is exceedingly rare in anuran amphibians. So far, only about 15 species (out of a total of over 6600) are known to be viviparous. Of these, only the West African toad Nimbaphrynoides occidentalis has a matrotrophic form of viviparity (the remaining species are ovoviviparous). Previous research indicated that foetuses of N. occidentalis start feeding from a very young age on, which necessitates a functioning musculocranial system, among other things. The extent as to which the foetal morphology differs from that of free-living aquatic tadpole larvae has been unclear though and we examined and described the morphology of the chrondrocranium, branchial apparatus and associated musculature. A series of foetuses at different stages were investigated using clearing and staining, histology and synchrotron micro CT scanning and subsequent computer aided 3D reconstruction. Overall, the structural organisation of the chondrocranium, lower jaw and the branchial apparatus of N. occidentalis does not differ substantially from that of free-swimming bufonid tadpoles. However, there are marked differences in the orientation and proportions of these structures. There are furthermore some reductions or fusions of several muscles. Because of the compression of the chondrocranium and the resulting shortening of the arcus subocularis and the processus ascendens, the origin and insertion of various muscles are reduced and the force produced for opening and closing the jaw is presumably somewhat decreased. All of these differences with free-swimming tadpoles are apparently related to the intrauterine feeding in N. occidentalis. Foetuses ingest an intrauterine secretion produced by the mother and keratinized jaws typical of tadpole larvae are missing.

POS2-52  4:30 pm  Diversification of pectoral girdle muscles within frogs (Amphibia: Anura). Engelkes K*, Universität Hamburg; Kleinteich T, Kiel University; Haas A, Universität Hamburg
Abstract: Frogs evolved a broad diversity of locomotor modes and uses of their forelimbs compared to their nearest relatives (caudates). Therefore, it appears more likely that adaptation of existing and development of new pectoral girdle muscles occurred in anurans, rather than a secondary simplification in the Caudata. The pectoral girdle muscles of basal and higher anuran and one caudate species (Hynobius tokyoensis) were compared using contrast-stained microCT-scanning, episcopic microscopy, virtual three-dimensional reconstructions, and dissections. Differences were coded in characters and character states and a mapping on a phylogenetic tree allowed for the reconstruction of ancestral states. The absence of girdle and girdle musculature in the immediate outgroup (caecilians) posed a conceptual problem in inferring ancestral character states. In the frogs examined, depending on the respective species, 27 to 34 muscles and muscle heads with connection to the pectoral girdle skeleton were identified, compared to 19 in H. tokyoensis. A number of muscles were present as one muscle belly in caudates but as two or more heads or portions at the base of or within anurans, and additional muscles occurred in anurans. We found interspecific differences in more than 50 muscle characters suggesting considerable variation in character states within Anura. The character mapping revealed potential apomorphies for nearly all clades among the frogs examined. Despite our data covering the basal branches, several ancestral character states and inter-order homologies remain uncertain for basal nodes in Batrachia and Anura, mostly due to the lack of shoulder girdles in caeciliens; studies on anuran muscle ontogeny might help determine polarity.

POS2-54  4:30 pm  Tipping the scale: Muscle mass distribution and its effect on center of mass position in the wild and modern domestic turkey. Stover KK*, Brown University; Roberts TJ, Brown University; Brainerd EL, Brown University
Abstract: The poultry industry has artificially selected for increased body size in the domestic turkey, resulting in dramatic changes over short evolutionary time scales. These animals provide the opportunity to study the evolution of morphological traits that have accompanied this change in body size. In this study we seek to determine: (1) if muscle groups of the modern domestic turkey have experienced the same proportional increase in size compared to wild turkeys; and (2) where the center of mass (CoM) position is located for comparison between the two strains. We dissected and measured muscle masses in 6 adult turkeys per strain. We grouped muscles by anatomical location (distal hindlimb, proximal hindlimb, trunk and forelimb) and calculated a ratio of muscle mass to total body mass. Only the trunk had significantly greater mass in the domestic turkey (P= 0.004). The sole muscle responsible for this increased proportional mass was M. pectoralis (P=0.002), which is strongly selected for breast meat in the poultry industry. In addition, the physiological cross-sectional area of the lateral gastrocnemius scaled with body mass0.73 in the wild turkey, but only body mass0.56 in the domestic turkey, indicating this leg muscle becomes relatively weaker as the birds grow. We measured the CoM position using a force plate and biplanar x-rays for accurate 3D measurements. The domestic turkeys’ CoM position is further anterior, in agreement with a prior study (Abourachid, 1993, Br. Poult Sci.). These results have implications not only for posture and effective mechanical advantage, but also, in conjunction with previously collected ontogenetic skeletal measurements, tell us how the musculoskeletal system evolves to deal with increased body mass.

POS2-56  4:30 pm  Three-dimensional analysis of rib kinematics during lung ventilation in the Argentine black and white tegu, Salvator merianae (Reptilia: Teiidae). Capano J.G.*, Brown University; Moritz S., Brown University; Brainerd E.L., Brown University
Abstract: Costal aspiration, in which rib movements generate the necessary thoracic pressures for lung ventilation, is the basal mode of breathing in amniotes. These movements are a complex combination of three-dimensional rotations that vary considerably within and between clades. Each rib can theoretically rotate about three axes: bucket-handle around a dorsoventral axis, caliper around a craniocaudal axis, and pump-handle around a mediolateral axis. The objective of this study is to understand the rib kinematics during breathing in the Argentine black and white tegu lizard, Salvator merianae. Tegu thoracic ribs have three mineralized segments: vertebral, intermediate, and sternal, whereas most non-serpentine squamates have only two segments, and snakes retain just the vertebral segment. We implanted radio-opaque markers into the vertebrae, sternum, vertebral, intermediate, and sternal ribs of three individuals, and the caudal-most cervical rib of one individual. With marker-based XROMM we generated 3D animations and quantified the axes of rotation. We found no measurable motion between vertebral and intermediate ribs, but there was motion between vertebral and sternal segments. This indicates that tegu ribs are functionally bipartite during breathing, despite their tripartite anatomy. Previous work in iguanas showed rib motions dominated by bucket-handle rotation, with very little caliper or pump-handle. Similar to iguanas, our data for tegus showed primarily bucket-handle rotation, but also showed substantially greater caliper and pump-handle motions, with high variability in the polarity, magnitude and relative timing of these rotations. The caudal-most cervical rib, which has no sternal attachment, showed substantial bucket-handle motion similar in magnitude and direction to the thoracic ribs. These findings have implications for understanding how ribs rotate without ventral articulations, including how snakes ventilate their lungs in the absence of a sternum.

POS2-58  4:30 pm  The effect of craniokinesis on the middle ear of domestic chickens (Gallus gallus domesticus). Claes R, University of Antwerp ; Muyshondt P, University of Antwerp; Van Hoorebeke L, University of Ghent; Dhaene J, University of Ghent; Dirckx J, University of Antwerp; Aerts P*, University of Antwerp
Abstract: The mammalian middle ear consists of an eardrum, three ossicles, two muscles and a number of ligaments, and is enclosed in a single bony structure. Ossicle movements, mediated by these muscles and ligaments, adapt sound transmission. The avian middle ear is simpler: an eardrum connected to one ossicle (columella), one muscle and one ligament. This seems to constrain adaptation capabilities. We hypothesize, however, that craniokinesis may play a role in the adaptation of sound transmission as the avian middle ear is not enclosed in one rigid structure, but also by the quadrate and by soft tissue. The eardrum is connected to the movable quadrate. Craniokinetic movements of the latter may thus effect the eardrum as well as the columella. To test this, hens and roosters (Gallus gallus domesticus) are used as models that differ in vocalization capacity. µCT-scans were made of the heads of 3 hens and 3 roosters, once with the beaks closed and once fully opened. A surface model was created to measure quadrate motion, displacement of the columella and changes in eardrum shape. Bony semi-circular canals of the inner ear were used to align models. We found no significant difference in beak opening, consequently neither in forward rotation of the quadrate, between hens and roosters. However, axial rotation of the quadrate about its squamosal-mandibular axis is significantly larger in roosters. These quadrate movements do not result in significant displacements of the columella, but do effect the eardrum. The strain of the membrane changes with beak opening in both sexes, and there is a clear displacement of the membrane, hence a deformation of the columella, in roosters. Based on these results we assume that craniokinesis may play a role in the middle ear. As sound production strongly differs between hens and roosters, the subtle difference in craniokinesis and its potential influence on eardrum mechanics may provide a protective mechanism for loud sounds during vocalization.

POS2-60  4:30 pm  The role of cervical air sacs in the vocalization of songbirds. Cozic A.M.*, Louisiana State University; Homberger D.G., Louisiana State University
Abstract: Whereas the structure and function of the sound-producing organ of birds, the syrinx, have been studied extensively, the structure and function of the supra-syringeal sound-resonating organs still await basic studies. To understand the complex interactions of these organs and their roles in generating the articulated tonal vocalizations of songbirds (e.g., the Northern Cardinal, Cardinalis cardinalis, and House Sparrow, Passer domesticus), a variety of complementary functional-morphological methods were applied: Micro-dissection; 3D imaging and modeling based on x-ray CT; and animation based on x-ray videography. Two pairs of cervical air sacs were discovered enveloping the supra-syringeal vocal apparatus and being enveloped by the cervical integument with its dermal musculature and the cervical cutaneous fasciae and musculature: The cervical diverticula of the cervico-cephalic air sac system cranially, and the parapatagial diverticula of the clavicular air sac of the pulmonary air sac system caudally. 3D animated models of singing Cardinals revealed that the tongue-larynx-trachea complex is protracted while the cervical vertebral column is retroflexed into a C-shape, thereby creating a space between the two structures when low-frequency sounds are produced. When high-frequency sounds are produced, the tongue-larynx-trachea complex is retracted, the cervical vertebral column returns to its relaxed S-shape, and the space between the two structures is reduced. We infer that the paired air sacs in the neck of songbirds are passively inflated and deflated to adjust to the fluctuating space between the trachea and cervical vertebral column and that their resonance can be regulated independently by the musculo-elastic system of the cervical cutaneous and dermal muscles to track the frequencies produced separately by the left and right parts of the syrinx. Supported by NIH grant NINDS R01 NS029467 & LSU Foundation fund "Functional Morphology of Birds"

POS2-62  4:30 pm  Virtual reconstruction of the skull of a large parrot (Aves: Psittaciformes: Ara macao), highlighting the anatomy of the brain endocast, inner ear, rhamphotheca, and kinetic apparatus. Nassif JP*, Ohio University; Ridgely RC, Ohio University; Witmer LM, Ohio University
Abstract: Parrots and their allies (Psittaciformes) are a speciose and highly divergent group of non-passerines known for their complex feeding behaviors and high cognitive capacity. As an outgrowth of projects on the evolution of the avian brain and cranial kinesis, an interactive 3D model of the skull of a scarlet macaw (Ara macao, OUVC 10633) was constructed. Voxel data were collected using micro-computed tomography (microCT). Subsequently, segmentation of anatomical structures was done in Avizo and 3D modeling in Maya. 3D PDFs were generated in Deep Exploration and Acrobat, and movies in QuickTime and Adobe Premiere. Interactive 3D models were also made available on Sketchfab. The resulting virtual skull highlights the anatomical basis for the prokinesis seen in large parrots: a well-developed craniofacial hinge, as well as the development of syndesmoses and diarthroses at the jugal and palatine articulations. The model also shows the high disparity between the extent of the rhamphotheca and the underlying bony jaws. Among the virtually reconstructed endocranial structures are the brain endocast, endosseous labyrinths of the inner ears, and neurovasculature. The endocast confirms previous descriptions of the Ara brain surface, including an expanded telencephalon with pronounced rostral notch and sagittal eminence, while resolving additional details, such as floccular shape and cerebellar foliation. We have assembled the resulting visualizations as an open-access online resource called the Visible Interactive Parrot (VIP) to serve as an educational tool for K–12 STEM educators, undergraduate and graduate students, and the public. Scarlet macaws are well-known members of this charismatic group, making them an ideal species for fostering public engagement. The VIP joins the existing library of Visible Interactive Animals on the WitmerLab website.

POS2-64  4:30 pm  Turbinal variation in high and low altitude populations of Peromyscus maniculatus . Pang B*, University of California, Los Angeles; Mayo K, University of California, Los Angeles; Van Valkenburgh B, University of California, Los Angeles
Abstract: At high altitudes, hypoxic and low-humidity conditions are common, contributing to a highly stressful environment and necessitating behavioral and physiological means of heat and water conservation. In many mammals, the challenge of water retention is handled by countercurrent airflow through a nasal turbinal complex, which reduces evaporative water loss and also helps retains heat. North American deer mice have one of the largest altitudinal ranges of any mammal, and display physiological and behavioral adaptations to stressful high-altitude conditions. Previous work has shown that mice living at high and low altitudes are genetically divergent, and that the hemoglobin of high-altitude mice has an increased affinity for oxygen. In addition, deer mice at higher elevations have increased ventilation rates. However, with increased ventilation also comes the potential for increased heat and water loss. Given these physiological stressors, we might expect to see compensatory modifications in the morphology of the turbinal system or nasal cavity. We tested this hypothesis by quantifying and comparing the surface area of the nasal turbinal surface areas of 28 deer mice specimens from high and low altitudes, using high-resolution CT scans, as well as performing a morphometric analysis of the skulls to assess if physiological stress affected skull morphology. Preliminary results suggest that there are small but significant differences between high and low altitude mice in turbinal surface area, but not nasal cavity dimensions. If preliminary results hold, this would be the first example of intraspecific variation in turbinal morphology in response to differences in habitat.

POS2-66  4:30 pm  Functional anatomy of the hind limb in Japanese cormorants (Aves: Phalacrocoracidae). Ichikawa M*, Okayama university of science
Abstract: Cormorants are excellent foot-propelled aquatic diving birds. They use two stroke phases during foot-propelled diving, the power stroke and the recovery stroke. In the recovery stroke, the foot is brought forward with flexing the digits, which closes the foot web and reduces water resistance. However, few functional anatomical studies have reported on digit movements during the recovery stroke in cormorants. The present study valuates the muscles of the hind limbs associated with digit movement during the recovery stroke in the Japanese cormorant Phalacrocorax capillatus. Three muscles play an important role in the recovery stroke: Musculus flexor perforatus digiti III (FPIII), M. flexor perforans et perforatus digiti III (FPPIII), and M. flexor perforatus digiti IV (FPIV). The tendons of the FPPIII and the FPIV perforate the lateral surface of the tendon of the FPIII on the distal end of the tibiotarsus. As FPPIII engages, digits III and IV are initially flexed together, as the three tendons cohere with one another. However, the tight contact of the tendons gets lost as the flexion progresses, as the tendons of FPPIII and FPIV taper off distally. Accordingly, digit III is more strongly flexed than digit IV, so that the two digits get in line anteroposteriorly. Thus, Japanese cormorants can decrease the water resistance occurring around the foot web during the recovery stroke.

POS2-68  4:30 pm  Morphological disparity, growth and life history variation in domesticated horses. Heck L*, Paleontological Institute and Museum, University of Zurich; Sánchez-Villagra M R, Paleontological Institute and Museum, University of Zurich
Abstract: Domesticated mammals offer a rich subject of investigation into the origins of morphological variation (disparity) within a species; experiments in evolution in which the developmental bases of such variation can be studied. We aimed to investigate in horses the influence of domestication on disparity and how it is generated in development by including the whole breadth in size (from the Falabella to the Shire). To quantify disparity of juvenile and adult skull shape we used three-dimensional geometric morphometrics in 30 domesticated horse breeds and 5 wild equid species. Statistical analyses showed that the morphological disparity in adult domesticated horse skulls exceeds that of the wild species and that domesticated breeds occupy regions of the morphospace that are not occupied by wild equids. Furthermore, results showed that paedomorphism serves to describe some of the shape changes in the skull of the Falabella when compared with normal-sized breeds. We also investigated the influence of domestication on life history variables by comparing gestation length, skeletal maturity, and growth rate among different horse breeds. For the gestation length our dataset included 27 breeds and results of multivariate statistics did not show significant differences among breeds. We further examined growth rates using histological markers in the femur of 7 breeds to investigate growth rate differences. Additionally, we investigated the timing of skeletal maturity by determining the state of cranial and epiphyseal suture closure in 30 breeds, and found that most markers of growth are conserved. Specific aspects of the anatomy are shown to exhibit differences (e.g., inner ear anatomy) between domesticates and wild forms, but separating adaptive from genetic drift effects, or other mechanisms, is difficult in these morphological studies.

POS2-70  4:30 pm  Morphology and mechanics of remora adhesion. Flammang B.E.*, NJIT; Beckert M.; Anderson E.J.; Nadler J.H.
Abstract: Adhesion, and in particular long-term reversible adhesion, to a wet or submerged surface is challenging. In the natural world, few organisms can adhere to underwater substrates and those that do generally use glue-like mechanisms or attach only to stationary objects. Remora fishes have evolved a unique adaptive ability - an adhesive disc formed from dorsal fin elements – that allows them to attach reversibly to actively deforming bodies of varying roughness and compliance that move at high speed. The adhesive disc is a hierarchical structure, in which the lamellae, spinules, fleshy outer lip, and cranial vessels all contribute to the generation of suction and friction for initial attachment and long-term hold. We found that remora body shape adds hydrodynamic advantages to adhesion and resistance to drag as well. The wall effect created by the flat disc approaching a host organism generates a suction pressure that helps to pull the remora to its host. Upon contact, the fleshy outer lip generates a viscoelastic seal as the lamellae rotate to produce a subambient pressure beneath the disc. Individual lamellar chamber pressures are equalized by the anterior cardinal sinus. Lamellar contact with the host engages spinule interaction with the host surface, thereby generating frictional forces that oppose shear. Our continued assessment of these mechanisms and the material properties of these structures is leading towards a bioinspired adhesive device that will be useful in ecology, medicine, and defense.

POS2-72  4:30 pm  Structure and motion over the fin-to-limb transition. Molnar J. L.*, Howard University; Esteve-Altava B., Royal Veterinary College and Howard University; Pierce S. E., Harvard University; Hutchinson J. R., Royal Veterinary College
Abstract: The fin-to-limb transition was a major evolutionary event in the history of life that influenced the subsequent morphology, lifestyle, and biodiversity of land vertebrates. Two questions remain relatively poorly understood: (1) how the various anatomical parts of limbs evolved semi-autonomously (modularity) while still growing and adapting in coordination (integration) and (2) the functional implications of these fundamental transformations in appendage morphology. This poster outlines our combined efforts to explore the structural and functional changes brought about by the fin-limb transition. We seek to unravel the evolutionary changes in modularity of the musculoskeletal system that occurred during the evolution of early tetrapods, how these newly acquired modular organizations facilitated the evolution of different morphologies for the forelimb and hindlimb, and how morphological changes in the limb bones and muscles of early tetrapods influenced their abilities to generate forces against the substrate and thereby achieve the water-land transition. The combined results of these two complementary projects are illuminating new aspects of limb evolution across the fin-limb and water-land transitions.

POS2-74  4:30 pm  Ontogeny of the West African caecilian Idiocranium russeli (Lissamphibia: Gymnophiona: Indotyphlidae). Theska T, Department of Comparative Zoology, Jena University; Mueller H*, Department of Comparative Zoology, Jena University
Abstract: Very few detailed descriptions of the skeletal and muscular development of caecilian amphibians are currently available. The recent studies show that there are disagreements concerning the homology of different skull bones and the number of different ossification centres. We investigated the embryonic and juvenile development of the skeleton and musculature of Idiocranium russeli, a miniaturised caecilian endemic to southwestern Cameroon. Idiocranium was suggested to be a direct developing genus like other members of the Indotyphlidae (e.g. Hypogeophis rostratus or Gegeneophis ramaswamii). Our results strongly support this hypothesis. The external morphology of different embryonic stages, the ossification sequence and the muscle configuration of I. russeli indicate heterochronic shifts of adult characteristics into embryonic development, as well as the loss or absence of various larval and metamorphic traits. For example, the maxilla and the palatine fuse to form the maxillopalatine well before hatching. This compound bone is typical for adult caecilians and forms during metamorphosis in most biphasic species. The tentacle, which normally also develops during metamorphosis, is already fully developed in late embryos. Furthermore, exclusive larval muscles like the M. interhyoideus or M. hyomandibularis are completely absent during ontogeny. The M. genioglossus and M. cephalodorsosubpharyngeus are present in embryonic development – a typical feature of direct developing caecilians. A larval ceratobranchial IV is also present, but fuses to the ceratobranchial III very early in ontogeny. The ossification sequence of Idiocranium is highly similar to those of G. ramaswamii and H. rostratus, but there are small differences like the coronoid starting to ossify earlier than in other indotyphlid species and the dermal pterygoid appearing comparatively late in ontogeny.

POS2-76  4:30 pm  Modeling the skeletomuscular system in Sea Lampreys (Petromyzon marinus): An integrative approach from microdissection, 3D imaging, and field observations. Wood B.M.*, Louisiana State University, Baton Rouge; Kynard B.E., University of Massachusetts at Amherst; Homberger D.G., Louisiana State University, Baton Rouge
Abstract: Lampreys play a key role in the reconstruction of the evolutionary history of vertebrates, but little is known about their functional morphology or their interactions with their environment. Our study integrates field observations and functional morphological studies of adult Sea Lampreys. We observed and video-recorded the body movements of spawning lampreys transporting stones to build nests and defending their territories in the high-velocity tributaries of the Connecticut River. Lampreys are capable of a much wider range of motion than gnathostomes: Dorsal and ventral flexions in excess of 90 degrees, lateral flexions up to 180 degrees, and twisting motions over 300 degrees. We hypothesize that the lamprey’s greater mobility may be at least partly due to the absence of a pectoral girdle, stiff vertebral column, and horizontal septum, which are characteristic of gnathostome fishes. To test this, we analyzed the fiber arrangement and orientation of the connective tissue and musculature of the trunk by microdissection and 3D modeling based on x-ray CT and MRI. The connective tissue skeleton comprises the dermis, a sub-dermal dorsal longitudinal ligament, and myosepta. The ligament sends and receives fibers from the dermis and medio-dorsal fascia, thereby acting as a node linking the dermis to the connective tissue skeleton anchored to the notochord and surrounding the coelom. The myosepta are actually formed by tendons extending from myomeric muscle fibers. Superficial tendons between muscles fibers of adjacent myomeres are aligned and, therefore, look like a “myoseptum.” Tendon fibers that dive medially join the deeper connective tissue skeleton. Hence, forces of contracting myomeres are transmitted across the myosepta as well as to the connective tissue anchored to the notochord and coelom enabling great flexibility of the body.

POS2-78  4:30 pm  Ultrastructural study of the skin of three caecilians (Ichthyophis tricolor, Uraetyphlus oxyurus, and Gegeneophis ramaswamii) from Western Ghats, India. . Damodaran Arun*, Central University of Kerala, Kerala, India; Ramachandran K, Government College Madappally, Kerala, India; Akbarshah M A, Bharathidasan University, Thiruchirapally, Tamil Nadu; Oommen V O, Kerala State Biodiversity Board, Kerala, India; Divya Lekha, Central University of Kerala, Kerala, India
Abstract: The aim of the present study is to investigate the skin structure of three adult caecilians belonging to Ichthyophiidae such as Ichthyophis tricolor,Uraetyphlus oxyurus, and Indotyphlidae as Gegeneophis ramaswamii. The SEM and TEM observations of their skin shows that skin is segmented with numerous glandular outlets in the dorsal, ventral and lateral regions. Round, oval, and polymorphic shaped glandular outlets were distributed in the skin.Ichthyophis tricolor skin has both collar type and funnel type glandular outlets but Uraetyphlus oxyurus and Gegeneophis ramaswamii has only collar type glandular outlet. Pore size and pore distribution in the skin are different in three species. The glandular outlets are situated on borders between adjacent cells and near one of the angles of the multifaceted epithelial cells in all the three species. Skin of Gegeneophis ramaswamii has many grooves distributed in the dorsal, lateral, and ventral skin surfaces along with the glandular outlets. These grooves were not present in skin of Ichthyophis tricolor and Uraetyphlus oxyurus. Skin has irregular shaped epidermal cells having microridges in them. Dorsal skin observed under TEM shows three layers of epidermis, stratum corneum, stratum spinosum, and stratum germinativum followed by the dermal layer. Flask shaped cells and merkel cells are also found in the epidermis. Two types of glands, mucus and granular glands, are present in Ichthyophis tricolor and Uraetyphlus oxyurus but Gegeneophis ramaswamii has only mucus gland. They were distributed in the dermis layer. Secretary granules are present in the granular glands. Mucus secreting granules are present in mucus glands. Both glands are layered by myoepithelial cells. This is the first report on the skin, skin glands, and glandular outlets of these three caecilian species. We hope that this study will penetrate deeper in to the knowledge about the skin morphology and poison biochemistry and pharmacology of these three species.

POS2-80  4:30 pm  Flow sensing in the deep sea: Novel observations on the mechanosensory lateral line system in stomiiform fishes. Marranzino A.N.*, University of Rhode Island; Webb J.F., University of Rhode Island
Abstract: The mechanosensory lateral line system (LL) in deep-sea fishes is relatively unknown, especially with regard to the Stomiiformes. Unlike melamphaids and gadiforms, which have obvious widened cranial LL canals with large neuromasts, hatchetfishes are reported to have less prominent LL canals and few superficial neuromasts (Handrick, 1901). We examined two important, commonly caught and widely distributed stomiiform taxa: hatchetfishes (Argyropelecus: Sternoptychidae) and bristlemouths (Cyclothone: Gonostomatidae) using modern methods to re-assess their LL morphology. High quality specimens were collected at sea (Tucker trawl) or obtained from museum collections and were examined using clearing and staining, whole mount hematoxylin staining, histology, µCT imaging, and SEM. Contrary to Handrick, who reported the presence of an unusually small number of neuromasts in Argyropelecus, we found lines and clusters of densely placed superficial neuromasts above and below the eye, on the cheek, along the mandible, and in discrete vertical lines on the trunk. In addition, canal neuromasts were identified in the predominantly unossified supraorbital canal and in unossified mandibular and preopercular canals. In contrast, Cyclothone lacks cranial canals and has small superficial neuromasts distributed in similar locations on the head and trunk, but they are not as proliferated as those in Argyropelecus. MicroCT imaging of representatives of several other stomiid genera reveals the presence of completely and incompletely ossified cranial canals in contrast to the reduction or absence of canals in Argyropelecus and Cyclothone. These findings suggest that the LL of stomiiforms is likely more important for mediating behaviors in the hydrodynamically quiet, and light limited deep sea than previously thought. Funded by NSF Graduate Research Fellowship and ANMH Lerner Grey Fund Award to ANM.

POS2-84  4:30 pm  Comparative anatomy of the facial muscles in Myocastor coypus (Mammalia: Myocastoridae). Taketani M*, Okayama University of Science
Abstract: The Musculus platysma and M. sphincter colli are specific facial muscles in rodents that facilitate their classification. The form of these facial muscles have been described in some species of Myomorpha and Sciuromorpha, but there have been few anatomical studies of the facial muscles in the Hystricomorpha. Here I report on the morphological characteristics and innervation of the facial muscles of three specimens of Myocastor coypus of the suborder Hystricomorpha. The origins of the M. platysma myoides and M. platysma cervicale are fascia on the M. masseter. The M. platysma myoides and M. platysma cervicale are inserted on the M. cutaneous maximus pars ventralis and M. cutaneous maximus pars dorsalis, respectively. These muscles are fused to each other at their origin. The cervical nerve inserts on the insertional part of the M. platysma myoides. Thus, the M. platysma myoides is not homologous to the M. platysma in terms of nerves supply from the facial nerve. The M. sphincter colli profundus originates from the cranial one-third of the sternum and inserts on the zygomatic arch. This M. sphincter colli profundus is described as covering almost all of the ventral neck region and is innervated by extra cranial branches of the facial nerve which supply the facial muscles. The M. sphincter colli profundus changes to a muscle when connecting bone to bone, although it is one of the facial muscles that are generally described as cutaneous muscles. These muscle features of M, platysma myoides and M. sphincter colli profundus have not yet been describe in other mammals.

POS2-86  4:30 pm  Preliminary investigations of cranial morphology in the Paradoxurinae (Mammalia, Carnivora, Vivveridae). Beery SM*, Ohio Northern University; McAfee RK, Ohio Northern University
Abstract: Paradoxurinae (e.g. palm civets, binturongs) are a subfamily of viverrids, which are primarily found in India, southeast Asia, and across some of the Philippine islands. The members of this group are arboreal, living high in dense forest canopy, and most individuals are solitary but not strictly territorial, and mainly nocturnal. Many aspects of this group are still relatively unknown, such as specifics related behavior and activities, as well morphological characters that would influence an understanding of those behaviors. For example, relationships among the group and other viverrids have been based on genetic characters with only a cursory examination of skeletal characters. Some molecular studies have placed Arctictis as the sister taxon to Paguma, while others have resulted in a closer association of the binturongs with the Viverrinae. Crania of Arctictis were compared to those of Arctogalidia, Paguma, and Paradoxurus in an attempt to resolve the molecular relationships with morphological data and characters. Arctictis easily separates based on its larger size and also differs significantly when viewed dorsally in the constriction of the braincase. This postorbital constriction occurs just behind the postorbital processes in the other paradoxurines and viverrinae but in Arctictis it is far posteriorly positioned. Arctictis does align with the others in the ventral extension of the paraoccipital bone below the ectotympanic bullae, except for Arctogalidia in which there is no ventral extension and the bullae are not enlarged. Arctictis also lacks a distinct sagittal crest and has very short postorbital processes. At present, there are many shared viverrid characters exhibited by Arctictis but the other characters examined do not strongly support its association with any of the other members of paradoxurinae nor those of Viverrinae.

POS2-88  4:30 pm  Comparative anatomy of the subscapularis, teres major, and latissimus dorsi muscles from salamanders to humans. Koizumi M*, Tokyo Ariake University of Medical and Health Sciences
Abstract: The shoulder girdle muscles in tetrapods, adapting to the terrestrial locomotion, have shown notable morphological changes in evolution. In this study, the phylogenetic differentiation of the subscapularis, teres major and latissimus dorsi muscles is studied. The observations were performed by dissecting the muscles together with the supplying nerves in amphibians (salamanders), reptiles (monitor lizards and iguanas), monotremes (platypuses and echidnas), marsupials (koalas and possums) and placental mammals (pigs, rats, dolphin, cats). The subscapularis in therians is innervated by the several subscapular nerves from the posterior cord of the brachial plexus. The proximal branches are originated from the ventral layer of the posterior cord and distal ones are from the dorsal layer near to the branches to the teres major. The thoracodorsal nerve to the latissimus dorsi arises independently from the posterior cord distal to the subscapular branches. In reptiles, the subscapularis and the scapulohumeralis posterior, which seems to correspond to the procoracohumeralis muscle in salamanders, are blended at insertion and receive common nerve branches. This fact suggests that the subscapularis in reptiles has a close relationship to the scapulohumaralis posterior, and probably to the procoracohumeralis in salamanders. The origin of the subscapularis in monotremes develops over the external surface of the scapula and this external part is innervated by the independent branch arising near to the branch to the teres major, which appears in mammals. Furthermore, this subscapular branch in monotremes, judging from its origin from the plexus, is thought to be homologous with the branch to the scapulohumeralis posterior in reptiles These results suggest that the caudal part of subscapularis and the teres major in therians can be differentiated from the scapulohumeralis posterior in reptiles and may have a close relationship to the procoracohumeralis in salamanders.

POS2-90  4:30 pm  The Myosin Heavy Chain specific A4.1025 antibody discriminates different cardiac segments in ancient groups of gnathostomes: Morphological and evolutionary implications. López-Unzu MA*, University of Málaga; Lorenzale M, University of Málaga; Soto MT, University of Málaga; Durán AC, University of Málaga; Sans-Coma V, University of Málaga; Férnandez B, University of Málaga
Abstract: The pan-Myosin Heavy Chain (pan-MyHC) marker MF20 have been reported to show similar, homogeneous signal in the myocardial segments of the heart of teleosts and tetrapods. However, in an ongoing study of the myocardial structure of the dogfish (Scyliorhinus canicula; Chondrichthyes), we observed differential immunostaining of the cardiac segments using another pan-MyHC, the A4.1025 antibody. In order to investigate the relevance of this finding for better understanding of the morphology and evolution of the vertebrate heart, we performed immunohistochemistry, slot blot and western blot in several species of chondrichthyans, actinopterygians and mammals using the above mentioned antibodies. In the dogfish heart, A4.1025 and MF20 specifically recognized MyHC isoforms, although with different degree of affinity. MF20 reactivity was homogeneous and high in all the myocardial segments. However, A4.1025 reactivity was heterogeneous. It was high in the sinus venosus (external layer), atrium and atrioventricular region, low in the ventricle and conus arteriosus, and null in the internal layer of the sinus venosus. A heterogeneous pattern of A4.1025 immunoreactivity was also detected in two other elasmobranchs, a holocephalan, a polypteryform and an acipenseriform. In all of these species, MF20 immunoreactivity was homogeneous. In addition, both markers showed a homogeneous immunoreactivity pattern in teleosts and mammals. Our results indicate that in the hearts of ancient gnathostomes, in all of which a conspicuous conus arteriosus exists, one or more MyHC isoforms with low affinity for A4.1025 show segment-specific distributions. Thus, A4.1025 appears to be an appropriated marker to identify the cardiac segments and their boundaries. We propose that the segment-specific distribution of MyHC isoforms may generate a particular type of myocardial contractility associated with the presence of a conus arteriosus. This work was supported by CGL2014-52356-P, CEIMAR, BIO 203 and FEDER.

POS2-92  4:30 pm  Comparative morphology of Horadandia Deraniyagala and Rasboroides Brittan (Teleostei: Cyprinidae). Batuwita S*, Postgraduate Institute of Agriculture, University of Peradeniya; Udugampala S, Society for the Biodiversity Conservation; Athauda S, Postgraduate Institute of Agriculture, University of Peradeniya; Edirisinghe U, Postgraduate Institute of Agriculture, University of Peradeniya
Abstract: Comparison of all congeners of Horadandia and Rasboroides disclosed two distinct genera by means of morphological differences except certain reliable characters; Horadandia (i.e., brittani+atukorali ) differs from Rasboroides (i.e., vaterifloris + nigromarginatus +pallidus + rohani ) by a consistent set of synapomorphies: (1) absence or presence of a bowl-shaped depression on the supraethmoid; (2) attachment of Baudelot's ligament on the dorsal part of the cleithrum, to distal end or not at the distal end, apart from the tip; (3) number of rows of pharyngeal teeth either 2 or 3; (4) presence of cusps or groves at apex of pharyngeal teeth and (5) lateral line absent or present (when present, incomplete). Horadandia and Rasboroides have long been in an uncertain taxonomic position. Hence, this study confirms the identity of both genera by giving modest (about15) characters, of which three character states were revealed by a previous study. The intraspecific variations of Horadandia and Rasboroides disclosed two distinct species represented by the former genus, whereas latter consisted of four. South East Asian cyprinid genus Trigonostigma Kottelat & Witte appears to be the sister genus of both Horadandia and Rasboroides . Congeners of Trigonostigma superficially resemble Rasboroides . Currently, these three genera show a disjunctive distribution pattern in South East Asia and in South Asia. However, according to a recent study, two regions were confluent during the early Eocene (about 35 Ma) as a single land mass (Eurasia+India). Hence, the common ancestor of Horadandia , Rasboroides and Trigonostigma may have lived around 35Ma in the land mass of Eurasia+India.

POS2-94  4:30 pm  Anatomical, histochemical and immunohistochemical characterization of the outflow tract of ray hearts (Rajiformes; Chondrichthyes). Lorenzale M*, University of Málaga; López-Unzu MA, University of Málaga; Rodríguez C, University of Málaga; Soto MT, University of Málaga; Sans-Coma V, University of Málaga; Fernández B, University of Málaga; Durán AC, University of Málaga
Abstract: Recent work has shown that the cardiac outflow tract of sharks and chimaeras does not consist of a single myocardial component, the conus arteriosus, as classically accepted, but two, namely, the myocardial conus arteriosus and the non-myocardial bulbus arteriosus. However, the anatomical composition of the outflow tract of the batoid hearts remains unknown. The present study was designed to fill this gap. The material examined consisted of hearts of two species of rays, namely, the Mediterranean starry ray (Raja asterias) and sandy ray (Leucoraja circularis). They were studied using scanning electron microscopy, and histochemical and inmunohistochemical techniques. In both species, the outflow tract consists of two components, proximal and distal with regard to the ventricle. The proximal component is the conus arteriosus; it is characterized by the presence of compact myocardium in its wall and several transverse rows of pocket-shaped valves at its luminal side. Each valve consists of a leaflet and its supporting sinus. Histologically, the leaflet has two fibrosas, inner and outer, and a middle coat, the spongiosa. The distal component lacks myocardium. Its wall consists of smooth muscle cells, elastic fibers and collagen. Thus, it shows an arterial-like structure. However, it differs from the aorta because it is covered by the epicardium and crossed by coronary arteries. These findings indicate that the distal component is morphologically equivalent to the bulbus arteriosus of sharks and chimaeras. In contrast to foregoing descriptions, the valves of the first transverse row are distally anchored to the bulbus arteriosus and not to the ventral aorta. Our findings give added support to the notion that presence of a bulbus arteriosus at the arterial pole of the heart is common to all chondrichtyans, and not an apomorphy of actinopterygians as classically thought. This work was supported by CGL2014-52356-P, CEIMAR, BIO 203 and FEDER.

POS2-96  4:30 pm  Additional articulations on the cervical and thoracic vertebrae and fossoriality in armadillos (Mammalia, Xenarthra). Castro M C*, Universidade de São Paulo; Galliari F C, Universidad Nacional de La Plata
Abstract: A previous abstract reported additional articulations on the cervical and thoracic vertebrae of Dasypus novemcinctus, Cabassous tatouay, and Euphractus sexcinctus. To further explore this character within extant Xenarthra the present contribution add observations on most taxa (13 out of 14 genera) and better characterizes those articulations, comparing their extension in the vertebral column to the presence and development of the xenarthrous articulations, as well as to the lifestyles. The additional facets are present only within the Cingulata clade (represented by armadillos), whereas the Pilosa (arboreal sloths and anteaters) lack them. They start on the posterior portion of the mesocervical bone and its extension is variable, usually reaching the posterior half of the thoracic series, but exceptionally spanning to the first sacral element in Chlamyphorus. In the cervical and anterior thoracic vertebrae, these facets are convex in the anterior surface of the vertebral body and concave in the posterior surface, placed at both sides of the intervertebral disc, which is reduced in size. In the posterior thoracic elements, the facets are flattened and displaced from the epiphysis of the body, becoming contiguous with the secondary (ventral) xenarthrous facets. The body facets described here are present in all fossorial xenarthrans, plus in the non-fossorial Tolypeutes. As the plesiomorphic lifestyle of armadillos is presumably fossorial, this condition in the latter taxon is attributed to phylogenetic inertia. In the case of Chlamyphorus, the greater extension of these articulations may be related to its extreme fossoriality, since it spends most of the lifetime underground. In terms of function, along with the mesocervical bone, these articulations would stiff the cervical series in lateral and torsional movements, acting as a better fulcrum for head-lifting digging [Funding: FAPESP 2014/23815-2 to MCC and CONICET to FCG].

POS2-98  4:30 pm  Evolution of spinal process shape and vertebral immobility in hominoids. Machnicki AL*, Pennsylvania State University; Reno PL, Pennsylvania State University
Abstract: The nature of the human/chimpanzee last common ancestor is fundamental for understanding the evolution of human bipedalism. A particular focus is the conformation of its spine. There are multiple mechanisms for stiffening the spine of apes, including reduction of the number of lumbar vertebrae, the level of the transitional vertebra where the articular facets change from coronal to sagittal orientation, and the shape and angulation of the spinous processes. There is debate regarding whether these features are homologous or homoplastic, and thus whether bipedalism evolved from a short stiff back like great apes or a longer lumbar column more similar to monkeys and Miocene hominoids. Genetic modification of Hox9 in mice results in the correlated modification of spinous process shape and placement of the transitional vertebra independent of alternation in lumbar number, mimicking evolutionary changes observed in hominoids. This indicates that the articular facets and spinous processes may be associated developmental modules. To test this hypothesis, we examined this change in spinous process across the thoracolumbar transition in hominoids. We used a NextEngine3D scanner to create surface scans of the lower thoracic and lumbar vertebrae of humans, gorillas, chimpanzees, orangutans, and gibbons in order to assess the angulation, orientation, and shape change of the spinous process relative to the position of the transitional vertebra and lumbar number. Humans and gibbons have a similar change in spinous process orientation and shape at the level of the transitional vertebra. Chimpanzees, gorillas, and orangutans each differ in their pattern of spinous process transition across the thoracolumbar boundary suggesting that mechanisms for lumbar stiffening in these taxa may be independently derived. This material is based upon work supported by the National Science Foundation under Grant No. DGE1255832 and by the Pennsylvania State University Hill Fellowship.

Contrast-enhanced CT (DCT)
POS2-100  4:30 pm  Physiological examination of ratite orthopedic disorders and soft-tissue visualization via micro-CT . Green TL*, Oklahoma State University Center for Health Sciences; Colorado State University; De Miranda Jr. MA, Colorado State University; Larson AM, Colorado State University; Bonitz SM, Colorado State University; Gignac PM, Oklahoma State University Center for Health Sciences; Kley NJ, Stony Brook University; Kanatous SB, Colorado State University
Abstract: Many hard-tissue (e.g., bone, dentine, enamel) pathologies directly impact the development and function of soft-tissue structures. Such pathologies can be unique to captive individuals and tend to be more common among large-bodied captives such as crocodilians, elephants, and flightless birds. Emus (Dromaius novaehollandiae) are large-bodied flightless birds that are uniquely efficient at both anaerobic sprinting and aerobic, sustained running. Native to Australia, they are commonly farmed in North America for oil and meat, but growth of the emu industry has been hampered by poorly understood orthopedic disease states (i.e., splayed-leg disorder). Few studies have examined captive emu skeletal muscle, and none have documented the enzymatic profile of ratite cardiac tissue. We sought to bridge this gap by providing a quantified understanding of physical degradation in this large farm-raised species. Surprisingly, we found the metabolic profile of captive emu cardiac tissue to be most similar to that of active, flying birds. Additionally, metabolic baselines for primary locomotor muscles between splayed and non-splayed limbs indicate enhanced metabolic enzyme activities and myoglobin levels, resulting in a distinctly more “athletic” phenotype than control limbs. This compensatory increase in aerobic capacity demonstrates how soft tissues can mitigate functional issues caused by pathologies and suggests that muscle atrophy does not contribute to splayed-leg disorder. Likely, other factors are to blame (e.g., nutrition). With the advent of more detailed imaging techniques, such as contrast-enhanced micro-CT imaging, we hope to test for signal of these factors and better understand the anatomy and physiology of health and disease states in ratite birds. Through documentation of the interplay between hard and soft structures, including their physiologies, we are now beginning to apply new tools to an ancient clade of poorly-understood birds.

POS2-102  4:30 pm  Contrast-enhanced versus phase-contrast imaging: costs and benefits of different methods. Herrel A*, CNRS/MNHN; Boistel R, Université de Poitiers; Adriaens D., Ghent University
Abstract: Recent years have seen a boom in the use of imaging for anatomical and functional studies. Tomography -based methods provide direct access to 3D structures, yet typically allow the visualization of 'hard' tissues (i.e., bone) only. Over the past decade contrast-enhanced methods have been proposed that allow the simultaneous imaging of 'soft' (e.g. muscle, nerves, organs, etc.) and 'hard' tissues by increasing the absorption of X-rays by soft tissues. These methods make use of contrast agents that stain the tissues and increase their density through the infiltration of radio-opaque solutions. Iodine staining is one of the most popular methods, but a host of other staining agents have been proposed. We here provide comparative results on the efficacy of different agents to stain different soft tissues (muscle, nerve, cartilage). However, for the imaging of museum specimens contrast-enhanced methods are often not allowed. Phase-contrast imaging can in this case provide an excellent and non-invasive alternative to contrast-enhanced methods. We briefly explain the method and show results in comparison with more traditional contrast-enhanced imaging.

POS2-104  4:30 pm  DiceCT and its applications for understanding the reptile musculoskeletal system. Holliday CM*, University of Missouri; Tsai HP, Brown University; Cost IN, University of Missouri; Sellers KC, University of Missouri; Lautenschlager S, Bristol University; Witmer LM, Ohio University
Abstract: Diffusible iodine-based contrast-enhanced CT visualization is now a standard approach to exploring morphology, refining phylogenies and testing hypotheses of animal function. Fewer anatomical systems lend themselves better to diceCT than the musculoskeletal system of reptiles, which arguably use more tendon and cartilage to construct their heads and limbs than do other amniotes. Here we showcase several lines of inquiry that use diceCT data collected from lizards, crocodylians, birds and mammals. First we use diceCT data to build 3D anatomical models to complement studies of trigeminal nerve evolution, sesamoid development, and jaw and limb muscle anatomy in alligators. Second, we use diceCT data to better understand morphologies of muscle architecture, aponeuroses, and other connective tissues to better inform 3D biomechanical models of skulls to test for patterns in cranial evolution . Third, we use diceCT data to investigate variation in muscle modeling methods.

Ecological Morphology (ECO)
POS2-106  4:30 pm  Substrate and limb evolution: a global ecomorphological analysis of ruminant unguals. Bormet AK*, Indiana University; Polly PD, Indiana University
Abstract: The Ruminantia (Artiodactyla, Mammalia) are prolifically found in a variety of environments. However, the suborder is considered to be best adapted to open habitats, in large part because of their simplified unguligrade morphology of two weight-bearing digits per hoof. The apparent discrepancy between the unified ecomorphology of ruminant feet and the variety of environments they inhabit calls for closer study of variation in limb morphology with respect to habitat. Previous studies have linked ungual features to environmental parameters in several dozen ruminant species. This research seeks to expand upon these studies by 1) examining ungual plantar morphology across the suborder to see if larger scale trends are ecologically, phylogenetically, or body size driven and, 2) generating an analogue that will be used for ecometric comparison to fossil unguals to allow for the reconstruction of paleoenvironments and the elucidation of ruminant response to climate change across the Cenozoic. Our study includes 720 unguals from 93 ruminant species; allowing us to examine ungual ecomorphological association with a global spectrum of habitats (i.e. prairies, deserts, tundras, forests, and swamps) and substrates (i.e. wet, ecotone, rocky and dry). We photographed skeletal ungual plantar (i.e. in contact with the ground) surfaces. Outlines with 100 semilandmarks were then Procrustes superimposed to produce shape variables for subsequent analysis. Results show, regardless of taxonomy, that species which live on fluidly unstable substrates- such as snow or sand, tend to have overall blunter shapes and flatter surfaces to the unguals, undoubtedly to aid in locomotion over the dynamic surface. Furthermore, this effect is strong in wild animals, but muted in captives suggesting that it is a plastic response to substrate. These results show that substrate is also an important factor in ruminant limb evolution-making ungual shape more than just a reflection of phylogeny.

POS2-108  4:30 pm  Ecomorphology of the hind limb long bones in Mustelidae (Mammalia: Carnivora). Botton-Divet L*, UMR 7179 MNHN/CNRS, Mecadev, Paris; Fabre A-C, UMR 7179 MNHN/CNRS, Mecadev, Paris; Houssaye A, UMR 7179 MNHN/CNRS, Mecadev, Paris; Herrel A, UMR 7179 MNHN/CNRS, Mecadev, Paris; Cornette R, UMR 7205 MNHN/CNRS/UPMC/EPHE, ISYEB, Paris
Abstract: Mustelidae display a wide range of ecologies, associated with a diversity of locomotor behaviors. The Mustelidae includes semi-arboreal, scansorial, terrestrial, semi-aquatic and semi-fossorial species with various degrees of specialization in each category. Bone anatomy reflects the interaction between functional adaptations, the phylogenetic background of an organism and the architectural and developmental constrains. Therefore the study of locomotor apparatus in a phylogenetic context is of great interest for understanding the adaptive nature of morphology. Here we investigate the anatomical trends associated with the different locomotor ecologies in Mustelidae. In contrast to the forelimb, the hind limb is almost exclusively devoted to locomotion making the hindlimb crucial in inferring locomotor ecology. Using 3D geometric morphometrics we investigated the hind limb long bone anatomy in Mustelidae. Using both anatomical and sliding semi-landmarks we quantify both the global geometry, the articular surfaces, and the diaphysis. We used these quantitative shape descriptors to test for the presence of a phylogenetic signal. Next, we test for differences in bone shape in animals with different locomotor ecologies while taking into account variation in body mass. Finally, we describe the changes in bone shape associated with each ecological group and discuss the functional consequences thereof.

POS2-110  4:30 pm  The evolution of median fin shape and its implications for swimming performance in the fish superfamily Balistoidea (Order Tetraodontiformes). George A.*, University of Chicago; Westneat M., University of Chicago
Abstract: Reef-dwelling fishes come in all shapes and sizes, and their high degree of morphological diversity is reflected by the large number of biomechanically distinct swimming modes employed by these fishes. Triggerfishes (Balistidae) and filefishes (Monacanthidae), comprising the monophyletic superfamily Balistoidea, exhibit a unique swimming mode, balistiform swimming, in which the median dorsal and anal fins provide most of the power. Balistiform swimmers lie on a biomechanical continuum from swimming powered by broad oscillations to precise undulations of the median fins. Interestingly, balistiform swimmers also possess median fins that lie on a morphological continuum from high to low aspect ratio (AR). Hydrodynamic theory predicts that fishes using higher AR fins for propulsion should be capable of higher endurance swimming performance, but reduced maneuverability. This performance trade-off is expected to correlate with habitat choice. Using morphometric analysis of museum specimens and photos from online databases and phylogenetic ancestral state reconstructions, I found multiple, independent decreases in dorsal fin AR within Balistoidea from a common ancestor with a mid-high AR dorsal fin. Additionally, nearly all filefishes have low AR dorsal fins. These results raise the possibility of declines in endurance swimming performance among multiple balistoid lineages. Alternatively, lineages with decreased AR fins may have evolved compensatory morphological or behavioral traits to maintain endurance swimming performance. Swimming performance tests and median fin kinematic analysis of balistoid fishes will determine whether decreases in median fin AR necessarily decrease endurance swimming performance and may reveal a potential relationship between fin shape and oscillatory versus undulatory fin kinematics. These experiments may also help elucidate the evolutionary origins, biomechanics, and habitat use of early balistiform swimmers. Funded by NSF grant IOS-1425049.

POS2-112  4:30 pm  A functional role for bipedal locomotion in lizards. McBrayer LD*, Georgia Southern Univ.
Abstract: A crucial aspect of the ecological morphology paradigm is the role of performance as the link between organismal traits and their fitness consequences in the environment. Behavior is also included in the paradigm as an additional link, especially when habitat variation is considered. Behavior serves to modulate, or potentially filter, performance variation, in direct and indirect ways. I will present data from studies examining the role of bipedal vs. quadrupedal locomotion in lizards. Bipedalism has been studied extensively, however the functional consequences and/or benefits of this behavior have remained elusive. I will show that some species of lizards modulate their use of bipedalism, and the use of the posture provides an advantage when crossing an obstacle. Furthermore, lizards employ a bipedal posture in a predictable manner as they encounter obstacles. Hence growing evidence supports a functional role for bipedal running behavior, and regardless of its origin, provides a mechanism for selection to maintain, or potentially enhance, its use in some lineages. In particular, this would be true for animals whose microhabitat might constrain performance traits such as maximal sprint speed. Instead acceleration, agility, or their combination, may be key traits correlated to fitness, and locomotor behavior may be a key selective filter.

POS2-114  4:30 pm  Do parasites have a place in ecomorphology? McElroy E*, College of Charleston; de Buron I, College of Charleston
Abstract: The mechanisms underlying parasite-altered host behavior and fitness remain largely unanswered. We argue that performance capacity is an important target of parasitic manipulation and we aim to integrate the study of animal performance and ecomorphology with that of parasitic manipulations of host behavior and fitness. We performed a meta-analysis of 101 measures of the effect of parasites on host performance capacity from the published literature to address the following questions. (1) Do parasites exert an important effect on host performance capacity? (2) Is that effect routinely to decrease or enhance performance capacity? (3) Which factors explain the effect of parasites on host performance capacity? and, (4) Do parasite impacts on morphology explain the changes in host performance? Although negligible-small effect sizes were detected in 40/101 measures, host performance capacity was overall affected by parasitic infection with a negative direction and medium-large magnitude in 58/101 measures and an increase in performance capacity in 3/101 measures. Host age, type of host performance, the host tissue infected by the parasite, and whether the study was experimental or based on natural infections each explained a significant amount of the variation in effect size. Finally, we explore how changes in host morphology result in changes in host performance. Overall, this work clearly demonstrates the link between parasites and host performance and function.

Fossoriality (FOS)
POS2-116  4:30 pm  Digging for clues: Methodological review of subterranean lifestyle inferences in fossil mammals. Selva C*, Centre de recherche sur la Paleobiodiversite et les Paleoenvironnements - Museum national d'Histoire naturelle - UPMC - CNRS; Ladevèze S, Centre de recherche sur la Paleobiodiversite et les Paleoenvironnements - Museum national d'Histoire naturelle - UPMC - CNRS; Peigne S, Centre de recherche sur la Paleobiodiversite et les Paleoenvironnements - Museum national d'Histoire naturelle - UPMC - CNRS; Germain D, Centre de recherche sur la Paleobiodiversite et les Paleoenvironnements - Museum national d'Histoire naturelle - UPMC - CNRS
Abstract: Current mammals include approximately 325 subterranean species over 4768 species in total. Although they are all subjected to the same underground environment stresses, extant taxa have very diverse lifestyles with different ecologies, diets and locomotion habits. Even the way to dig takes different forms: with the teeth, claws, paws, and head. Is the past diversity of the subterranean taxa similar? And how do we infer subterranean lifestyle on fossils? The oldest occurrence of fossorial behavior has been documented through taphonomy. Indeed burrows are often found on paleontological sites since their sedimentation is different from the surrounding area. For example, fossils of the fox-sized cynodont Thrinaxodon are relatively common in the Lower Triassic deposits of South Africa. The fossorial skeletal specializations are also clues to determine the subterranean lifestyle for mammaliaform lineages. Hypertrophied burrowing limb features reflect scratch digging activity. Specific head morphology could translate adaptations for chisel-tooth or head-lift digging activities. The aim of this study is to set up a new subterranean lifestyle inference model based on the inner ear morphology. The sensitivity to head rotations and locomotor behaviors are related to the inner ear. The head movements play a significant role in the subterranean lifestyle: no matter how digging, the head is much sought. The inner ear had to manage this intensive and frequent head movements, thus these mechanical stresses must influence the morphology of the organ. The project aims to highlight the correlation between the anatomy of the inner ear and the burrowing lifestyle. Placed in an evolutionary and temporal context, these results will clarify the importance of this way of life in the mammal history, particularly during major biological crises.

Inner and Middle Ear (EAR)
POS2-118  4:30 pm  The bony labyrinth morphology helps to recalibrate the Cervidae tree. Mennecart B*, Natural History Museum, Basel, Switzerland; Costeur L, Natural History Museum, Basel, Switzerland; Bibi F, Museum für Naturkunde Berlin, Leibniz Institute for Evolution and Biodiversity Science, Germany; Métais G, CNRS-Museum National d'Histoire Naturelle, Paris; Rössner GE, Bayerische Staatssammlung für Paläontologie und Geologie, Germany; DeMiguel D, Catalan Institute of Palaeontology Miquel Crusafont, Spain; Schultz G, Biomaterials Science Center, University of Basel, Switzerland; Müller B, Biomaterials Science Center, University of Basel, Switzerland
Abstract: Molecular clock analyses calibrate the origin of crown Cervidae within the Late Miocene (7-10Ma), even if stem Cervidae appeared almost 10Ma earlier. The relationships within the living deer appear to be resolved based on molecular data (mitochondrial and nuclear). However, no phylogenetic hypothesis based on morphological characters alone reflects the molecular-based topology. For example, Megaloceros is either part of the basal radiation of Cervus (molecular data), or of the Dama radiation (combined analyses of molecular and morphological), or closely related to the "basal Cervini" Eucladoceros (morphological). In addition, morphological studies indicate crown Cervidae could have arisen in the Middle Miocene. Our study on cervid evolutionary history includes 13 living species in all the tribes and 14 fossil ones. We investigated the bony labyrinth shape and perform a 3D geometric morphometrics analysis. We show that Early Miocene Cervidae have similar primitive bony labyrinth morphology that (together with their ancestral antlers) support an attribution to stem Cervidae. The Middle Miocene Euprox possesses a derived morphology of the inner ear corresponding to those of crown deer. Considering its antler morphology, it possibly represents Muntiacinae and accordingly the oldest known crown deer (13.5Ma). Further morphological distinctions can be done between the bony labyrinth of the different subclades (Capreolinae and Cervinae) based on the lateral canal. Moreover, closely related genera present a similar endolymphatic sac shape supporting molecular data (Dama/Pseudodama/Megaloceros; Rusa/Cervus; Hydropotes/Capreolus). Based on these new data, a molecular clock analysis is under process testing previous results on the divergence times of the various cervid genera.Study supported by the SNF project 200021-159854.

POS2-120  4:30 pm  Sound transmission pathway in protocetids (Mammalia: Cetacea). Mourlam MJ*, Institut des Sciences de l'Évolution de Montpellier (ISEM - UMR 5554 UM-CNRS-IRD); Orliac MJ, Institut des Sciences de l'Évolution de Montpellier, France
Abstract: Extant cetaceans are fully aquatic mammals which diverged from terrestrial artiodactyls around 55 million years ago. They present deep modifications of their sensory organs, notably of the sound perception pathway. Archaeocetes are a paraphyletic assemblage of early diverging cetaceans. They show a diversity of morphologies of the petrotympanic complex and ossicles documenting a variety of sound transmission mechanisms from mostly terrestrial configuration to fully aquatic layout. Protocetids are semi-aquatic archaeocetes that maintain a strong relation with land (e.g. parturition on land). The auditory region of these so called "transitional" forms is only partly known. The middle Eocene locality of Kpogamé, Togo (46–43 Ma) has yielded abundant material documenting the auditory region of protocetids cetaceans including twelve fragmentary bullae, one isolated petrosal and one petrotympanic complex. The CT-scan investigation of the petrotympanic complex revealed for the first time in situ ossicles of a protocetid. These remains allow refining the hypothesized mechanism of the sound transmission pathway from the surrounding environment (air or water) to the fluid filled cochlea in protocetids. The morphofunctional study of the auditory region remains from Kpogamé indicates that optimal audition abilities in both air and water were most probably possible in protocetids. The latter indeed retained i) a wide tympanic ring indicating the presence of a functional tympanic membrane, ii) non-fully modified ossicles and cochlea, and iii) a petrosal-bulla contact suggesting a possible bimodal functioning of the petrotympanic complex with a "switch system" that could "open" or "close" the middle ear. Finally, the morphology of the cochlea supports the hypothesis of ancestral low frequency sensitivity in cetaceans and sets this state of character back to middle Eocene times.

POS2-122  4:30 pm  Inner ear orientation shows head posture in extant rhinos (Perissodactyla: Rhinocerotidae). Schellhorn R*, Steinmann-Institut, Paläontologie, Universität Bonn
Abstract: Among extant perissodactyls five rhinoceros species exist. Two of them are African species and three are Asian with different feeding strategies. The African black rhino (Diceros bicornis), and the Asian Indian (Rhinoceros unicornis) and Sumatran rhinos (Dicerorhinus sumatrensis) are all mixed feeders. In comparison, the Asian Javan rhino (Rhinoceros sondaicus) is a pure browser, while the African white rhino (Ceratotherium simum) is a pure grazer. The latter two species display different habitual head postures: "horizontal" in the Javan rhino and "hanging" in the white rhino. Behavioral studies show that mixed feeding species are carrying their heads between "horizontal" and "hanging". The different head postures are expressed by the inclination of the occiput, which is backward inclined in grazers and forward inclined in browsers. Re-organization of the occipital region during phylogeny also involves the ear region. Therefore, nine skulls of extant rhinos have been scanned with CT to virtually reconstruct the bony labyrinth. The orientation of the inner ear's lateral semicircular canal, normally aligned parallel to the ground, was used to show the resulting habitual head posture. In accordance with occiput inclination the browsers show a horizontal and the grazers a downward oriented skull. During rhinoceros evolution two trends became obvious, some rhinos developed large horns, while others evolved lower tusk-like second incisors. Both characters were used for fighting. The results of the study furthermore suggest, that the adaptation to feeding preferences developed first while protectable weapons (large horns in downgrade headed grazers, lower tusks in horizontal headed browsers) developed later via natural selection. This research received support (FR-TAF-3483) from the SYNTHESYS Project which is financed by European Community Research Infrastructure Action under the FP7 "Capacities" Program.

POS2-124  4:30 pm  Digging into mammal inner ear morphology: new insights into subterranean lifestyle determination using 3D landmarks inference model. Selva C*, Centre de recherche sur la Paleobiodiversite et les Paleoenvironnements - Museum national d'Histoire naturelle - UPMC - CNRS; Germain D, Centre de recherche sur la Paleobiodiversite et les Paleoenvironnements - Museum national d'Histoire naturelle - UPMC - CNRS; Peigne S, Centre de recherche sur la Paleobiodiversite et les Paleoenvironnements - Museum national d'Histoire naturelle - UPMC - CNRS; Ladevèze S, Centre de recherche sur la Paleobiodiversite et les Paleoenvironnements - Museum national d'Histoire naturelle - UPMC - CNRS
Abstract: The sensory systems of balance and hearing is located in the bony labyrinth in the periotic bone. Across mammals, the general morphology of this bony labyrinth is similar, but the detailed morphology varies even among closely related groups showing that the shape of the labyrinth carries valuable functional and phylogenetic information. The sensitivity to head rotations and locomotor behaviors are related to the sizes, shapes and orientations of the bony labyrinth and particularly the semicircular canals. The head movements play a significant role in the subterranean lifestyle: depend the way of digging, the head is much sought. The bony inner ear had to manage this intensive and frequent head movements, thus these mechanical stresses must influence the morphology of the organ. In this study, to characterize the particular morphology of the bony inner ear of subterranean mammals, we constituted a comprehensive sampling including at least one species within every strictly subterranean clades. Adding to this 45 species, we completed our sampling with two phylogenetic closest species one belonging to a fossorial lifestyle and one to a terrestrial lifestyle (total of 130 specimens). This was done for control purposes, to discriminate phylogenetic and functional signals. Thanks to semilandmarks-based three-dimensional geometric morphometric approach, we characterize the shape of the labyrinth. Preliminary results suggest that subterranean mammals have an osseous labyrinth thicker than terrestrial generalist. Using multivariate statistics, we set up a subterranean lifestyle inference model. The established correlations will allow inferring a lifestyle to fossil taxa. Placed in an evolutionary and temporal context, these results will clarify the importance of this way of life in the mammal history, particularly during major biological crises.

Muscle Functional Morphology (MFM)
POS2-126  4:30 pm  Comparative myology and adductor leverage in phalangeriform possum jaws. Harper TH*, Johns Hopkins University, SOM; Perry J, Johns Hopkins University, SOM
Abstract: Phalangeriform possums are a radiation of omnivorous arboreal marsupials native to the Australian Biogeographic Region. These species utilize highly variable ecological strategies, with a concomitantly diverse range of dental morphologies and cranial geometries. For instance, there is considerable variation in the degree of development of the plagiaulacoid lower third premolars, reduction in size and number of cheek teeth, and conical to chisel-shaped lower procumbent incisors with variably present post-incisor diastemata. This morphological diversity is interesting in its own right, but also presents a unique opportunity to investigate a largely unrecognized case of marsupial–placental convergence, as the earliest (“plesiadapiform”) primates show many general and detailed morphological similarities with these possums. To characterize the myology and occlusal forces correlated with the above-mentioned hard anatomy, the dissections of four possum taxa are reported here. The sampled genera include Acrobates, Petaurus, Trichosurus, and Phalanger; representing the range of body sizes and foraging modes found in this suborder. The muscles of mastication were resected and then chemically dissected to analyze the distribution of skeletal muscle fiber lengths in each discrete muscle belly. This information was used to estimate Physiological Cross Sectional Area (PCSA) and to test for adaptation for wide gape. The attachments, orientations, and lever arms corresponding to the major jaw adductor groups were defined using photographs of dried specimens, and estimates of bite force and joint reaction force were calculated using simple lever mechanics. Results of this project include the finding of a stark divergence in the relative size of the temporalis group between Acrobates and Petaurus, two otherwise similar small, gliding possums; and the lack of adaptation for wide, muscularly-limited gape in these same taxa.

Secondary adaptation to aquatic life (AQU)
POS2-128  4:30 pm  Ontogenetic development and intraspecific variability of bone microstructure in the king penguin Aptenodytes patagonicus: considerations for paleoecological inferences in Sphenisciformes. Canoville A*, Steinmann Institute for Geology, Mineralogy and Paleontology, University of Bonn, Bonn, Germany; de Buffrénil V, CR2P, Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements, Sorbonne Universités, CNRS/MNHN/UPMC, Muséum National d'Histoire Naturelle, Paris, France
Abstract: Birds have colonized various ecological niches during their evolutionary history and several lineages adapted to the aquatic environment. Numerous papers focused on the long bone microstructure in aquatic birds. Some studies attempted to reconstruct the evolution of aquatic adaptations in a given lineage, based on the bone microstructure of fossil taxa, without referring to a comparative set of modern taxa. These works often drew ecological deductions from one or two bones of a single specimen. However, the ecological signal contained in bone microstructure is known to vary between skeletal elements. Bone microstructure can also be affected by other factors (besides lifestyle), which have been overlooked in lifestyle inferences. Studies on intraspecific variability and bone microstructural development during ontogenesis are rare in the field of comparative bone histology, although such works are essential for the choice of standard parameters for bone description and for drawing rigorous paleobiological inferences. We sampled all major limb bones of hatching, juvenile and adult specimens of the king penguin Aptenodytes patagonicus, in order to assess the extent and the causes of limb bone microstructural variability during ontogenesis. This species is ideal for such study because factors that could affect its bone microstructure (a unique growth cycle and distinct locomotor behaviors between juveniles and adults) are well documented. Histomorphometric observations reveal that bone microstructure vary greatly during ontogenesis. Limb bones undergo an intense remodeling episode during the juvenile molt. Moreover, these bones show different developmental patterns during the individual's life. Finally, for a given long bone, even adult specimens exhibit variability in compactness. This work is intended to constitute a comparative basis for the histological study of extinct Sphenisciformes, and thus provide a better framework for paleobiological reconstructions.

POS2-130  4:30 pm  Biomechanical and physiological signals in the vascular system of Squamata in the context of secondary adaptation to an aquatic life. Dumont M*, UMR CNRS/MNHN 7179, Mecadev Adaptative mechanisms and evolution; Houssaye A, UMR CNRS/MNHN 7179, Mecadev Adaptative mechanisms and evolution
Abstract: Bone vascularization has been shown to be an important marker for bone mechanical properties and animal growth. Consequently, different inner vascular structures should be observed in animals with distinct physiologies and ecologies. Major changes in vascularization are thus supposed to occur in the context of secondary adaptation to an aquatic life, where various habitat, swimming modes, gravity control strategies and physiologies occur. For such a study, it was of great interest to focus on ectotherms. We decided to analyze squamates. Indeed, this group displays several forms that are adapted to a marine habitat (e.g., marine snakes, "dolichosaurs", mosasauroids) and also illustrates various steps in a progressive transition from terrestrial to aquatic lifestyles. As this lineage includes snakes, we focused our research on vertebrae. We used synchrotron microtomography in order to qualify and quantify precisely their vascular network in three dimensions. Clear variations in the vascular organization (e.g., vascular canal diameter, volume, orientation, connectivity)show that distinct locomotion mechanisms affect the vascularity of vertebral centra. Differences in vascular orientation are clearly observed: terrestrial forms have no or a few radial vascular canals, aquatic forms present a dense radial organization with anastomoses, and aquatic mosasauroids forms have a more longitudinal organization. These results confirm previous (2D) histological observations, but deliver a more precise quantification of the canal structure in 3D. This study establishes for the first time the link between vascularization and locomotion and physiology in the context of secondary adaptation to an aquatic life.

POS2-132  4:30 pm  Dietary transitions and the evolutionary origin of whales: 3D texture analysis of tooth microwear in archaeocetes and extant analogues. Goodall R. H., University of Leicester; Purnell *, University of Leicester
Abstract: The origin of whales is associated with a significant dietary transition: from terrestrial omnivory/herbivory to aquatic piscivory/carnivory. This occurred between the evolution of the earliest Pakicetidae (early Eocene ca. 52.5 Ma) and the emergence of crown group whales near the Eocene/Oligocene boundary (ca. 33.7 Ma). Morphological and isotope analyses suggest an extensive mid-late Eocene semi-aquatic stem lineage, preceding obligate aquatic lifestyles in later stem clades, and transition to the marine realm within protocetids. However, neither morphological nor isotope data reveal direct evidence of trophic ecology. We have employed a novel approach - quantitative 3D-microtextural analysis - to provide new tests of hypotheses of ecological transitions in whale evolution. This technique, developed from engineering approaches to surface metrology, uses quantification of tooth surface textures to provide direct evidence of tooth-food interactions and diet. It is a well established technique for dietary analysis in terrestrial mammals, but has not previously been applied to aquatic mammals. Our statistical comparison and multivariate analysis of microtextures in extant pinnipeds and odontocetes provides the first evidence that tooth microtextures vary with diet in modern aquatic mammals. Applying this relationship to archaeocetes, we find evidence of clear differences in diet which are not correlated with phylogenetic position. These results paint a more complex picture of dietary evolution in archaeocete whales than previously hypothesised.

POS2-134  4:30 pm  Water as a driver of evolution: the example of aquatic snakes. Segall M.*, MECADEV (MNHN) - PMMH (ESPCI); Cornette R., ISYEB (MNHN); Fabre A-C, MECADEV (MNHN); Godoy-Diana R., PMM (ESPCI); Herrel A., MECADEV (MNHN)
Abstract: Evolutionary trajectories are often biased by development and historical factors. However, the environment can also impose constraints on the evolutionary trajectories of organisms leading to convergence of morphology in similar ecological contexts. For example, the physical properties of the medium an animal moves through can impose strong constraints. Aquatic animals are principally faced with drag-related forces impeding movement. These hydrodynamic constraints are strong and have resulted in the independent evolution of suction feeding in nearly all groups of secondarily aquatic tetrapods. Despite the fact that snakes cannot use suction, they have invaded the aquatic milieu many times independently. Here we test whether the aquatic environment has constrained head shape evolution in snakes and converge on shapes predicted by biomechanical models. Our results show that aquatic snakes partially conform to our predictions and have a narrower anterior part of the head and dorsally positioned eyes and nostrils. This morphology is observed irrespective of the phylogenetic relationships among species suggesting that the aquatic environment does indeed drive the evolution of head shape in snakes.

Xenarthra (XEN)
POS2-136  4:30 pm  Advantages and limitations in the use of extant xenarthrans (Mammalia) as morphological analogues for paleobiological reconstruction. Vizcaíno SF*, Museo de La Plata, Argentina
Abstract: A characteristic feature of the clade Xenarthra is the enormous disparity between extant and extinct diversity, with living species representing a severely restricted sample of the total diversity achieved by the group. The morphology of an organism is restricted or moderated by its evolutionary history and thus is not solely a product of a particular habitat. Given the constraints imposed by shared history, the extant representatives of the three major groups of xenarthrans provide a valuable basis for paleobiological inference. However, when structures and functions are unique to or autapomorphies of a fossil organism, patterns extracted from a phylogenetic framework do not necessarily lead to paleobiologically useful information. Many extinct xenarthrans are morphologically different from their living relatives to such a degree as to suggest they had very different modes of life; compare, for example, fossil sloths to living tree sloths and glyptodonts to armadillos. For such cases, the extinct forms have no modern analogues and the application of an overly straightforward actualistic approach may produce nonsensical reconstructions. For instance, due to the unusual lateral expansion of the femur, the use of a single allometric equation based on the transverse diameter of the femur -a measurement used extensively in estimating body mass in mammals- produces an estimate of 98 tons for the elephant-sized ground sloth Megatherium. This, however, does not invalidate actualism and the use of analogues. Rather, it requires their extension into the application of other, such as mechanical, approaches that address form-function relationships but are not necessarily based on already-known biological comparators.

POS2-138  4:30 pm  An isolated petrosal of the pampathere Holmesina floridans (Mammalia, Xenarthra, Cingulata) from the Blancan NALMA of Florida. Gaudin T.J.*, Univ. of Tennessee at Chattanooga
Abstract: Work on the cranial anatomy of the pampathere Holmesina floridanus, known primarily from abundant remains recovered from the Haile 7G quarry of north central Florida (late Blanca NALMA, Pliocene), has revealed an extremely well-preserved isolated left petrosal from a subadult individual (UF 248500). This specimen is the first isolated pampathere petrosal to be formally described. Comparisons to the extant armadillos Dasypus and Euphractus and the Miocene armadillo Proeutatus, the latter considered the sister taxon of pampatheres and glyptodonts, reveals a number of distinctive features. The fenestra cochleae is extremely compressed dorsoventrally, its width nearly three and a half times greater than its depth, whereas in other cingulates it is more ovate, its width no more than twice its depth. The crista interfenestralis bears a bony bridge connecting it laterally to the medial side of the tympanohyal, forming a partial floor to the facial sulcus. The promontorium bears both a narrow, spine-like anteromedial process, plus a rounded boss on its lateral surface that likely marks the origination of the m. tensor tympani. The internal acoustic meatus is deeply recessed, situated very near the ventral margins of the intracranial exposure, and its two primary divisions, the foramen acusticum superius and inferius, are separated by a very narrow, sharp ridge. There are several features linking Proeutatus to Holmesina exclusive of the living taxa, including a mediolaterally broadened crista interfenestralis and an elongated anteromedial process of the promontorium, that suggest the petrosal may prove an informative source of systematic characters among cingulates, and perhaps within pampatheres themselves.

POS2-140  4:30 pm  Pedolateralization, foot anatomy, and weight support in extinct sloths (Xenarthra, Folivora). Toledo N*, División Paleontología Vertebrados, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, CONICET; Racco A, Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, CONICET; Bargo MS, División Paleontología Vertebrados, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, CIC; Vizcaíno SF, División Paleontología Vertebrados, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, CONICET; Fernicola JC, Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, CONICET
Abstract: Both extant and extinct sloths show a peculiar pes configuration defined as pedolateral or invertigrade, which is present in different degrees throughout the clade. Pedolaterality was primarily described for sloths by Owen in the XIX century and later revised and discussed by Hirschfeld in 1985. Some of their features (medial rotation of the foot arch and caudal extension of calcanei tuber, for instance) can be recognized also in the non-pedolateral anteaters (Xenarthra, Vermilingua), resulting in a conflictive anatomical distinction. Morphological criteria for pedolaterality definition are discussed herein, as well as the trajectory of body weight force distributed to the pes through the talo-crural joint and its relation with weight-bearing, and the degree of pedolaterality. Miocene Santacrucian (~ 17-19 Ma) sloths showed a pentadactyl, conservative pes with slightly pronounced pedolaterality traits, where the trajectory of the weight fall within the weight-bearing surface conformed by the calcaneal tuber, the metapodials IV and V, and the ungual phalanxes. Such a configuration is kept until the Pleistocene by the Megalonychidae. On the other hand, among Pleistocene sloths (Megatheriidae and Mylodontidae) the pedes showed an extreme reduction of inner digits. In these more pedolateral morphs, the body rested exclusively on weight-bearing surfaces conformed by the calcaneum and metatarsals IV and V, almost without the participation of digits II and III (the only ones carrying functional ungual phalanxes). The weight trajectory would be inner to these foot rest surfaces, resulting in a mechanically unstable configuration, especially critical for these giant-sized sloths. As a result it is proposed the presence of a medial plantar pad that could expand the weight-bearing surface allowing a more direct and efficient weight distribution and support, analogue to the condition observed in modern proboscideans.

POS2-142  4:30 pm  Species delimitation and morphological variation in the skull of long-nosed armadillos (Dasypus). Billet G*, CR2P, Museum national d'Histoire naturelle, Paris, France; Hautier L, ISEM, University of Montpellier, France; de Thoisy B, Institut Pasteur de Guyane, Cayenne, France; Delsuc F, ISEM, University of Montpellier, France
Abstract: With their Pan-American distribution, long-nosed armadillos (genus Dasypus) constitute an understudied model for Neotropical biogeography and the Great American Biotic Interchange. This genus comprises seven described species with distributions covering much of South America, Central America, and parts of North America. The nine-banded armadillo (D. novemcinctus) has the widest distribution ranging from Northern Argentina to the South-Eastern US where it became invasive less than 200 years ago. This ubiquitous species occurs in a broad diversity of habitats such as savannahs, dry forests, and rain forests. Nine-banded armadillos therefore provide an ideal model to explore the effects of climatic and biogeographic events on morphological diversity at a continental scale. For that matter, we used an integrative taxonomy approach coupling classical comparative anatomy methods with cutting-edge 3D-geometric morphometric techniques. Alongside treatment of traditional diagnostic characters, some internal characters that could be reliably and repeatedly assessed were chosen, as they seemed to vary significantly in the specimens sampled, and 3D reconstructions were performed. Our preliminary analysis of internal structures successfully retrieved a taxonomic differentiation between Dasypus species and a geographical differentiation within D. novemcinctus. Geometric morphometric data were collected for a sample of 150 specimens using µCT-scans, and results were contrasted with new molecular-based species delimitations. Our study first revealed strong phylogenetic and geographical imprints on the cranial and mandibular morphological traits. We also made use of the morphological data to evaluate variation in skull morphology as a result of ecological factors. These data constitute a necessary step towards understanding the exceptional adaptive potential of this species distributed across a wild diversity of habitats and environments across the continent.

POS2-144  4:30 pm  Feeding ecology in Oligocene mylodontoid sloths (Mammalia, Xenarthra) as revealed by orthodentine microwear analysis. Kalthoff DC*, Swedish Museum of Natural History; Green JL, Kent State University at Tuscarawas
Abstract: Recently, dental microwear analysis has been successfully employed to xenarthran teeth. Here we present new data on use wear features on 17 molariforms of Orophodon hapaloides and Octodontotherium grande. These taxa count among the earliest sloths and are known from the Patagonian locality La Flecha (Deseadan SALMA, late Oligocene). Modern phylogenetic analyses classify Octodontotherium and Orophodon within Mylodontoidea with whom they share lobate cheek teeth with an outer layer of cementum and a thick layer of orthodentine but are different in showing an only narrow vasodentine center. Four representative target areas of 0.01 mm2 were analyzed on the orthodentine surface of each tooth under incident light on a stereomicroscope at a magnification of 70x. Four quantitative (number of small pits, number of large pits, number of fine scratches, number of coarse scratches) and two qualitative parameters (presence/absence of gouges and puncture pits) were examined by only one observer (DCK). Results were compared to extant sloths (Bradypus, Choloepus) and published data from fossil sloths (Acratocnus, Megalonyx, Megatherium, Thinobadistes). Numbers of small and large pits, of fine scratches as well as presence of puncture pits are very similar in Octodontotherium and Orophodon, but the latter shows more coarse scratches (not significantly different). Microwear features suggest that both taxa fed on plant material with low to moderate intrinsic toughness with both taxa also including tougher food items (e.g. fruit) in their diet. Frequent gouging of the tooth surfaces also suggests that extrinsic factors, such as possible heavy intake of abrasive grit, may be influencing tooth wear. These interpretations support the reconstruction of (1) Deseadan environments as open habitats with spreading savannas/grasslands and (b) both taxa as wide-muzzled bulk feeders at ground level.

POS2-146  4:30 pm  Tarsal morphology and weight support in the evolution of glyptodonts (Mammalia, Xenarthra, Cingulata). Fernicola JC*, CONICET-Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales "Bernardino Rivadavia"; Universidad Nacional de Luján; Toledo N, CONICET; División Paleontología Vertebrados, Unidades de Investigación Anexo Museo, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata; Bargo MS, CIC; División Paleontología Vertebrados, Unidades de Investigación Anexo Museo, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata; Vizcaíno SF, CONICET; División Paleontología Vertebrados, Unidades de Investigación Anexo Museo, Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata
Abstract: Glyptodonts (middle Eocene-early Holocene) are a group of herbivorous placental mammals that evolved in America, characterized by a rigid dorsal carapace and elephantine hind-feet, among other features. Several authors considered that the relationships between the tarsal elements in the small Miocene taxa and in the larger Pleistocene glyptodonts were different. A reexamination of the tarsal joint pattern of glyptodonts, their sister-group pampatheres, and armadillos is presented here. Among glyptodonts, the tarsal bones of the Miocene Propalaehoplophorus (~80 kg), and the Pleistocene Glyptodon (~800-2000 kg), Neosclerocalyptus (~600 kg), Doedicurus (~1500 kg) and Panochthus (~ 1000 kg) share a unique articulation pattern, in which the distal facet of the lateral cuneiform articulates with both metatarsals III and IV. This pattern allowed an interlocking of the mid-tarsal segment of the foot, and would enable a more widespread distribution of the weight loads from astragalus to I-IV digits. In the Pleistocene pampathere Holmesina (~180 kg), extinct armadillos Proeutatus (Miocene; ~15 kg) and Eutatus (Pleistocene; ~50 kg), and extant Chaetophractus (~4 kg), Priodontes (~45 kg) and Dasypus (~2.5 kg), the distal facet of the lateral cuneiform articulates only with metatarsal III, allowing distribution of the weight load from talus to digits I-III. The glyptodont pattern showed variation throughout the clade, concurrent with the increase in body size of this group from Miocene to Pleistocene. The articular contact between the ectocuneiform and the metatarsal IV increases from 1/5 of the distal facet of the cuneiform in the smallest Miocene taxon, to 1/2 of the facet in larger Pleistocene genera. Although it seems clear that the rol of this articulation pattern was not to support a large body size in Miocene glyptodonts, it enabled reaching giant body sizes throughout the evolution of the group.

POS2-148  4:30 pm  3D finite element analysis of lower jaws in glyptodonts. Tambusso P.S*, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay; Marcé-Nogué J., Centrum fur Naturkunde, University of Hamburg, Hamburg, Germany; Fortuny J., C2RP, CNRS-MNHN-UPMC, Paris, France; Institut Català de Paleontologia Miquel Crusafont, Cerdanyola del Vallès, Spain.; Varela L., Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay; Fariña R.A., Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
Abstract: Finite element analysis (FEA) has proved to be a powerful tool for biomechanical studies in comparative frameworks. In the case of xenarthrans, the analysis of the mandible of extant and extinct armadillos showed a correlation of the stress patterns with diet preferences and variability. In this work we analyze the mandible of 3 glyptodonts, two Pleistocene giants Glyptodon and Panochthus, and the smaller Miocene Pseudoplohophorus, to evaluate the diet preferences inferred by ecomorphological studies. Their peculiar jaw anatomy, with the toothrow located medially to the ascending ramus, renders most morphometric analyses nearly inviable. In order to comprehend their complete anatomy, the mandibles and skulls were 3D digitized. The musculature modeled to determine the vector forces in the FEA models includes temporalis, masseter and pterygoid. A transformation was applied to the FEA models to render the forces applied comparable. Four cases were evaluated: A, vertical constrain in the anteriormost tooth; B, vertical constrain in the posteriormost tooth; C, horizontal constrain in the posteriormost tooth and D, vertical and a horizontal constrain in the posteriormost tooth. In all glyptodonts, case B generated the highest amount of stress in the occlusal surface. This is congruent with the proposed propalinal mastication at the posteriormost tooth due to the telescopic migration of the mandible. Regarding cases A, C and D, highest amount of stresses are located in the ascending ramus and the posteriormost part of the symphysis. According to the mechanical advantage value, Panochthus has the highest bite force values, followed by Glyptodon and Pseudoplohophorus. This could be congruent with the proposed bulk-feeding diet for Panochthus and selective-feeding diet for Pseudoplohophorus, while Glyptodon could be intermediate between these.

POS2-150  4:30 pm  Inner and middle ear 3D reconstruction of the extinct giant sloth Lestodon armatus. Varela L, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay; Tambusso PS, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay; Fariña RA*, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
Abstract: Here we describe the bony labyrinth and middle ear ossicles of the giant ground sloth Lestodon armatus from the Arroyo del Vizcaíno site (AdV), through CT scans and structured light scanning, and compare it with those of extant and extinct sloths. Recent descriptions of the inner ear of Megatherium americanum and extant sloths have shown that semicircular canals (SCs) morphology of the giant ground sloth departs from the morphology of extant sloths. The SCs of Lestodon are thin and larger than in extant sloths, similar to Megatherium; the lateral and posterior canals do not form a secondary crus commune. With an average radius of curvature of 3.8 mm and a body mass estimation of 4500 kg, Lestodon shows levels of agility similar to Megatherium, that is, higher than extant sloths. A preliminary analysis of the inner ear of the extinct ground sloth Catonyx cuvieri shows that the morphology of the SC is very similar to that of Lestodon and Megatherium. In a phylogenetical context, this corroborates the convergent size reduction of the SCs in both extant sloth taxa due to the parallel acquisition of slow and suspensory locomotion. Several middle ear bones of Lestodon has been recovered from the AdV site. A complete chain of middle ear ossicles, malleus, incus and stapes, has been recovered from the right side of one skull. They have an excellent preservation, keeping even the most delicate structures as the manubrium mallei throughout its length and the lenticular process of the incus, a very small and delicate structure that articulates with the stapes. The ossicles were digitized using a structured light scanner. The digital models were used to reconstruct the life position in the middle ear and subsequently to perform finite element analysis and physical models to assess the hearing capabilities.

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