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Volume 29, Supplement to Number 3 September 2009
69th Annual MeetingSociety of Vertebrate Paleontologyand the 57th Symposium of Vertebrate Palaeontology and Comparative Anatomy (SVPCA)
University of BristolBristol, United KingdomSeptember 23-26, 2009
Program and Abstracts
Vol. 29, Supplement to No. 3, September 2009
Vol. 29, Su
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University of Bristol
136A © 2009 by the Society of Vertebrate Paleontology
Poster Session III, (Friday) SIGNIFICANT MID-LATITUDE ARIDITY IN THE MIDDLE MIOCENE OF EAST AISALIU, Liping, Department of Geology, University of Helsinki, Helsinki, Finland; ERONEN, Jussi, Department of Geology, University of Helsinki, Helsinki, Finland; FORTELIUS, Mikael, Department of Geology, University of Helsinki, Helsinki, Finland
The East Asian climate history during the Neogene is a complicated and contentious issue, in particular because of its bearing on the development of the East Asian monsoon and Tibetan uplift chronology. Here we present a paleoprecipitaion analysis based on mean molar tooth height (hypsodonty) of large herbivorous mammals to investigate the spatial pattern of climate zonation in East Asia during the middle Miocene. We show a generally humid and uniform situation before the late middle Miocene, replaced by a mid-latitude arid belt from the late middle Miocene, into the earlier part of the late Miocene. These findings are concordant with the global phenomena of the middle Miocene climate optimum and the subsequent cooling, and suggest that the predominant climate in East Asia for most of the Miocene was planetary rather than monsoonal. Our results support a late initiation of the East Asian summer monsoon, coincidentally with the beginning of eolian red clay deposition in the later late Miocene at 7-8 Ma.
Poster Session III, (Friday) ARE BIPEDOPUS, SEMIBIPEDOPUS, LACERTIPUS, NAVAHOPUS AND BRASILICHNIUM DISTINCT ICHNOGENERA? REEVALUATING JURASSIC TRACKS FROM THE WESTERN USALOCKLEY, Martin, University of Colorado at Denver, Denver, CO, USA; TEDROW, Allen, Idaho Museum of Natural History , Pocatello, , ID, USA
Bipedopus, Semibipedopus and Lacertipus are ichnogenera proposed for Lower Jurassic vertebrate tracks from near Meeker, Colorado. The tracks, which occur in eolian facies of the Navajo-Nugget Sandstone, are similar to the larger ichnogenus Navahopus and the smaller South American ichnogenus Brasilichnium. Both names are presently applied to tracks from the Navajo Sandstone in southern Utah. However, the former three names, with potential priority, have never been used, nor have detailed comparisons been made between these ichnogenera. Diagnostic track features are evaluated in order to determine whether: 1) the track names are valid, 2) the named ichnogenera differ from one another, 3) the ichnogenera suggest diagnostic track makers. Preliminary results indicate that Lacertipus is valid and different from the other ichnogenera due to its tetradactyl elongate track shape and large manus (slight heteropody). It is of probable lepidosaur affinity, but very similar to Dolichopodus from the Permian. Bipedopus and Semibipedopus are short, wide tetradactyl tracks with pes larger than manus (moderate heteropody). They differ only in the sporadic presence of the smaller manus track. So Bipedopus could be an extra-morphological variant of Semibipedopus caused by pes on manus overprinting, or the consistently faint manus traces may indicate a trackmaker placing very little body weight on forelimbs. In the latter case Semibipedopus is a fair descriptor. Brasilichnium and Navahopus have pes tracks very similar to Bipedopus and Semibipedopus (and the Permian ichnogenera Chelichnus and its junior synonym Laoporus). Navahopus is larger than Brasilichnium but both have a small manus (strong heteropody). All are of probable synapsid affinity, although Navahopus has also been attributed to a prosauropod. Clear differentiation of manus and pes track morphology and heteropody in well-preserved specimens are crucial for differentiating these ichnogenera both within the Jurassic and in Mesozoic-Paleozoic comparisons. Distinct patterns of heteropody may help reliably differentiate ichnotaxa.
Romer Prize Session, Thursday 8:30FUNCTIONAL SHIFTS DURING GROWTH IN THE LATE JURASSIC THEROPOD DINOSAUR ALLOSAURUS: THE IMPLICATIONS OF ONTOGENETIC VARIATIONLOEWEN, Mark, University of Utah, Salt Lake City, UT, USA
Paleobiological studies must often cope with small sample sizes, so for most taxa, it is unclear what effect ontogeny and intraspecific variation have on functional morphology during an organism’s lifetime. The large theropod dinosaur Allosaurus—known from numerous associated and articulated specimens and thousands of individual elements—currently provides the best opportunity to address this critical, unresolved issue. I focused my study on the skull and hindlimb, completing a morphometric analysis of over 570 bivariate comparisons for 1,300 specimens. Analysis of the skull, combined with stratigraphic assessments of individual specimens, indicates the presence of two temporally-separated species of Allosaurus in the Late Jurassic Morrison Formation: A. fragilis (Brushy Basin Member) and A. n. sp. (Salt Wash Member). Cranial elements reveal an increase in skull height vs. skull length during growth for both species, suggesting that these ontogenetic trends are conservative across the two taxa. In A. fragilis, but not in A. n. sp., the caudal portion of the skull exhibits extreme positive allometry, substantially increasing in transverse breadth and ventrally displacing the jaw joint relative to the tooth row, an unusual condition among theropods that mirrors the ontogenetic trajectory of T. rex. Significant increases in skull height and breadth, as well as an overall increase in robustness and re-organization of skull architecture, are postulated to be functionally linked with heightened stress and loading associated with adult predation and feeding. Analysis of hindlimb allometry reveals significant growth-related changes in both species, including: relative shortening
and thickening of the entire limb, reduction of the femoral medullary cavity, and distal movement of the insertion point for the major limb retractor muscles. These patterns are interpreted as indicative of an ontogenetic shift in locomotor strategy from more agile, cursorial juveniles to a more graviportal adult condition. Taken together, cranial and hindlimb changes during the growth of Allosaurus suggest a shift in lifestyle from agile, generalist juveniles to graviportal, specialist adults.
Poster Session II, (Thursday) HISPANOMYS BIJUGATUS (RODENTIA, CRICETODONTINAE) FROM THE MIDDLE MIOCENE OF LA GRIVE-SAINT-ALBAN (FRANCE): BIOSTRATIGRAPHICAL IMPLICATIONSLÓPEZ-ANTOÑANZAS, Raquel, Museo Nacional de Ciencias Naturales - CSIC , Madrid, Spain; MEIN, Pierre, Université Claude Bernard - Lyon I, Villeurbanne , France
La Grive-Saint-Alban is the name used to refer to various Upper Aragonian pits located on the territory of the municipality of Saint-Alban-de-Roche (Isère, France). All pits have yielded micromammals, but remains of Hispanomys have been only recovered from La Grive L (pit Lechartier, with eight fissure-fillings numbered from L1 to L8) and La Grive M (pit Milliat). Two species of this genus have been identified at La Grive-Saint-Alban: H. bijugatus from La Grive L (fissures L3 and L5) and H. decedens from La Grive L (fissure L5 and maybe L7), La Grive M as well as from an unnamed fissure-filling. H. bijugatus shows some of the typically primitive dental characters of the Aragonian species of Hispanomys, such as the unreduced M3. However, it also presents progressive features: the absence of labial and lingual cingula surrounding the upper and lower molar valleys respectively, the increase of the number of roots on the second lower molar, and the lost of mesolophs on the upper molars. All these characters are lacking in H. decedens. All in all, H. bijugatus appears as a relatively derived species with respect to the coeval congeneric species. The age of the different fissure-fillings of La Grive-Saint Alban is controversial. Because H. bijugatus and H. decedens are believed to be closely related species within the same lineage, the fact that the former shows a more progressive dental morphology than the latter suggests that the unnamed fissure-filling from La Grive and La Grive M (with H. decedens only) are older than La Grive L3 (with H. bijugatus only). The coexistence of the two species at La Grive L5 may indicate an intermediate age for this locality. Should the extremely low percentage of H. decedens in the sample from L7 not be due to “contamination”, this locality may be older than La Grive L3 and L5.
Technical Session V, Wednesday 2:15HOMOLOGY OF THE INFRAORBITAL BONES AND THE MONOPHYLY OF SEMIONOTIFORMESLÓPEZ-ARBARELLO, Adriana, Bayerische Staatssammlung fuer Palaeontologie und Geologie, Munich, Germany
The monophyly of Semionotiformes (including the gars, semionotids and macrosemiids) is supported by several characters, in particular the presence of anterior infraorbital bones, which constitute a unique synapomorphy of this group. The term ‘anterior infraorbitals’ refers to the infraorbital bones placed anterior to the anterior border of the orbit (preorbitals, lacrimals, or antorbitals of other authors). Similarly, the ‘toothed infraorbitals’, placed between the antorbital and the anterior infraorbitals, constitute a synapomorphy of the Lepisosteidae. Postorbitals and suborbitals, subinfraorbitals and postinfraorbitals, and a jugal have been identified among the series of dermal bones associated with the infraorbital sensory canal in actinopterygians. However, the number of infraorbital bones is highly variable and individual homologies cannot be established. The association of each of these bones with particular neuromasts of the infraorbital line does not provide a valid criterion of homology because the number of neuromasts in this sensory canal is variable between species of the same genus, between specimens of the same species, and sometimes even between the left and right sides of the same specimen. Nonetheless, developmental studies have shown that all the ossifications associated with the infraorbital line occur in connection with one or more neuromasts and through the same process. Therefore, serial homology can be inferred for the whole series from the rostral to the dermosphenotic. Within the series of infraorbital bones in the Semionotiformes, the anterior infraorbitals and toothed infraorbitals can be distinguished clearly on the bases of their morphology and position. These bones complete the infraorbital series between the antorbital and the orbit and, although individual homologies cannot be proposed, the subseries of ‘toothed infraorbitals’ and ‘anterior infraorbitals’ are shown to be homologous and uniquely derived in the Lepisosteidae and the Semionotiformes respectively.
Poster Session I, (Wednesday) BIOTIC RESPONSE TO THE LATE GLACIAL MAXIMUM IN SOUTHERN EUROPELÓPEZ-GARCÍA, Juan Manuel, Institut de Paleoecologia Humana i Evolució Social (CSIC associated unit), Tarragona, Spain; BLAIN, Hugues-Alexandre, Institut de Paleoecologia Humana i Evolució Social (CSIC associated unit), Tarragona, Spain; CUENCA-BESCÓS, Gloria, Ciencias de la Tierra, Paleontologia, Universidad de Zaragoza, Zaragoza, Spain
Until now, the biotic response to one of the harshest periods of the Pleistocene (called the Late Glacial Maximum = LGM) has been known in Europe from a few marine or lake
JVP 29(3) September 2009—ABSTRACTS 137A
palynological sequences. A number of caves in northern Spain provide new insights into the continental sequences with a continuous record of small vertebrates, some of them with pollen as well. The el Portalón cave in the Sierra de Atapuerca (Burgos, northwestern Spain) provides a long, continuous continental sequence divided into sixteen lithostratigraphical sublevels (P16 to P1), with a set of radiocarbon dates from 30 kyr BP to 17 kyr BP. This sequence has already yielded a rich assemblage of small-vertebrates (more than 18,000 bones), mainly composed of small-mammals, amphibians and squamate reptiles. The faunal list includes at least 25 species:4 amphibians (Alytes obstetricans, Bufo bufo, Bufo calamita and Rana temporaria); 3 squamates (an indeterminate lacertid, an indeterminate colubrine and Vipera sp.); 6 insectivores (Sorex gr. coronatus-araneus, Sorex minutus, Neomys fodiens, Neomys anomalus, Talpa europaea and Galemys pyrenaicus); 2 chiropters (Myotis myotis and Myotis gr. myotis-blythi);10 rodents (Microtus arvalis, Microtus agrestis, Microtus oeconomus, Iberomys cabrerae, Chionomys nivalis, Terricola duodecimcostatus, Arvicola sapidus, Arvicola terrestris, Apodemus sylvaticus and Eliomys quercinus). Within this sequence, P6 to P3 sublevels are related with the LGM and are characterized by a strong decrease in summer temperature with an important increase in winter precipitation and a diminution of woodland areas. This period corresponds to the disappearance of “thermophilous” and water-stream taxa such as I. cabrerae, T. duodecimcostatus, A. sapidus, N. fodiens and G. pyrenaicus as well as woodland-edge taxa such as E. quercinus, A. sylvaticus and M. myotis. Nevertheless, more than a decrease in biodiversity, this period is characterized by a very strong decrease in the number of individuals (i.e. biomass). The biotic response to this coldest period is analyzed separately for small-mammals, squamate reptiles and amphibians permitting a scenario in accordance with their different ways of life and biological plasticity.
Poster Session IV, (Saturday) MONOSPECIFIC ASSEMBLAGES OF SMALL OVOID THEROPOD EGGS FROM THE UPPER CRETACEOUS OF THE AREN FORMATION (SOUTH CENTRAL PYRENEES, LLEIDA, SPAIN)LÓPEZ-MARTÍNEZ, Nieves, Universidad Complutense de Madrid, Madrid, Spain; VICENS BATET, Enric, Universitat Autònoma de Barcelona, Bellaterra, Spain
Small ovoid eggs with prismatic eggshells are recorded in two rich, monospecific concentrations from a correlated single level of upper Cretaceous (upper Camapanian-Maastrichtian) coastal deposits of the Aren Formation (South-central Pyrenees, Lleida, Catalonia, Spain). Many other egg assemblages with different prismatic and tubospherulitic egg types appear in other levels of similar coastal facies in the Aren Fm and in other lithostratigraphic units of different facies in the Pyrenean and Provençal region as well; however this new, isolated egg type has been only recorded up to now in these two sites. Its overall egg size and shape are similar to modern hen eggs, which is unusual in the egg world record of this age. Its shape resembles to smaller Campanian avian eggs from the Bajo-de-la-Carpa Formation (Argentina), however the new eggshell microstructure differs by having a peculiar pattern of interlocking palisade prisms with an incipient squamatic texture, instead of the thick squamatic layer commonly present in true avian eggshells. A preliminary egg morphospace analysis situates both fossil ovoid eggs midway between modern bird eggs and non-avian theropod eggs. This new egg type is attributed to a small theropod, probably owing a single oviduct like birds and having a mosaic distribution of primitive and derived features between non-avian theropods and birds, which adds more arguments for supporting the close phylogenetic relationships between both groups.
Poster Session I, (Wednesday) RECONSTRUCTION OF PLEISTOCENE SOUTHEAST ASIAN ENVIRONMENTS THROUGH MEGAFAUNA COMMUNITY ANALYSISLOUYS, Julien, Liverpool John Moores University, Liverpool, United Kingdom; MEIJAARD, Erik, The Nature Conservancy, Balikpapan, Indonesia
Megafauna (large-bodied species) are the most frequently recovered mammals from Pleistocene sites in Southeast Asia. Although environmental inferences have been made in the region on the basis of individual species, the scarcity of micromammals from most sites has hampered multivariate environmental reconstructions. We reconstructed the habitat types of 30 Pleistocene sites in Southeast Asia through synecological (community) analysis. This method specifically targets large-bodied mammals, and as such can be applied widely in the region. Ecological variables were chosen such that these can be directly assessed from species lists. The method allows the reconstruction of fossil sites as closed (continuous tree cover), mixed (heterogeneous tree cover) and open (limited to no tree cover). Four Pleistocene sites can confidently be assigned to one of the three habitat types. Tam Hang, a Middle Pleistocene site from Laos, is classified as mixed. Ban Fa Suai, a Middle Pleistocene site from Thailand, is also classified as mixed. Trinil, a Middle Pleistocene site from Java, is classified as open. Lastly Hang Hum II, a Late Pleistocene site from Vietnam, is classified as open. Insufficient numbers of fauna are present in the remaining sites to allow strictly confident habitat assignment. Nevertheless, conditional habitat assignments can be achieved, and are largely congruent with other paleoenvironmental data obtained from the literature. The analyses suggest that through most of the Pleistocene, Southeast Asia was composed of mixed habitats, and that the widespread distribution of rainforests, such as found today, is a relatively rare phenomenon.
Edwin H. and Margaret M. Colbert Poster Competition (Thursday)SOMATIC RESEGMENTATION ERROR: A CONGENITAL PHYSICAL ANOMALY IN A SPECIMEN OF APATOSAURUSLOVELACE, David, University of Wisconsin - Madison, Department of Geology and Geophysics, Madison, WI, USA
Physical anomalies in the fossil record, though rare, can lend insight into developmental and evolutionary histories. A recently discovered mid-caudal vertebra of Apatosaurus exhibits an unusual morphology consistent with a congenital anomaly associated with errors during somatic resegmentation. The specimen exhibits two stunted neural arches fused to a single vertebral body of normal (expected) size; a single stunted haemal arch is also present and fused to the mid-ventral surface of the vertebral body. Aside from the anomalous neural and haemal arch, the vertebral body does not differ appreciably from that of the expected condition. During embryogenesis the development of the axial column proceeds through a number of steps that are not altogether understood; however, recent chimeric and molecular studies have unambiguously demonstrated that a vertebra is composed of cells from two adjacent somites (i.e. resegmentation). Cells from the leading somite contribute to the anterior portions of the neural arch, laminae, processes, and vertebral body, while the following somite contributes to the posterior portions of the same vertebra. It is hypothesized that during this stage of development the somites - that contributed to the vertebra under investigation - incompletely assimilated, leading to disordered vertebral segmentation (e.g. block vertebrae). The only reported instance of block vertebrae in the fossil record was observed in a Tyrannosaurus specimen. The presence of congenital physical anomalies in the axial column of Apatosaurus, a taxon that has greater than 80 caudal vertebrae, is not too surprising; however, physical anomalies such as this provide a unique window through which early development can be viewed.
Technical Session V, Wednesday 3:30THE CRANIAL ANATOMY OF A NEW TETRAPODOMORPH FISH FROM THE LOWER DEVONIAN OF CHINALU, Jing, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China; ZHU, Min, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China
Previous studies have suggested that the divergence between dipnomorphs and tetrapodomorphs occurred prior to the Lochkovian, however, the history of the latter can only be definitely traced back to the late Emsian with Kenichthys. Here we report a new tetrapodomorph fish from the Pragian Posongchong Formation of Yunnan, southwestern China that extends the earliest record of tetrapodomorphs to at least 10 million years earlier in the geological history. The new form agrees well with Kenichthys and ‘osteolepiforms’ in the pattern of neurovascular openings on the lateral wall of neurocranium, and the flat parasymphysial dental plate. It bears the largest orbital notch relative to the parietal shield length and the most anteriorly positioned pineal foramen among basal tetrapodomorphs, and a large tusk on the parasymphysial dental plate. The new form resembles basal dipnomorphs (e.g. Youngolepis and Powichthys) and Styloichthys in a broad and elongate parasphenoid. Characters shared with Styloichthys, Youngolepis, Kenichthys and Thursius wudingensis include the infraorbital sensory canal following the premaxillary suture, and a compound cheek bone plate with three pits. The unique character combination of the new form further bridges the gap between tetrapodomorphs and dipnomorphs, and provides a novel insight into the character acquisition sequence of stem tetrapods. High-resolution CT scan data of an anterior cranial portion of the new fish have been acquired via the scanning facilities at the Australian National University, Canberra. The scanning and digital imaging offer an opportunity to depict a complete three-dimensional ethmosphenoid region from a very early tetrapodomorph, and allow for detailed comparisons between the neurocrania of basal tetrapodomorphs and other sarcopterygians.
Poster Session III, (Friday) VERTEBRATE FAUNA, STRATIGRAPHY AND AGE OF THE WHITAKER QUARRY (GHOST RANCH, NEW MEXICO), THE RICHEST UPPER TRIASSIC DINOSAUR QUARRY IN THE WORLDLUCAS, Spencer, New Mexico Museum of Natural History, Albuquerque, NM, USA; HECKERT, Andrew, Appalachian State University, Boone, NC, USA; RINEHART, Larry, New Mexico Museum of Natural History, Albuquerque, NM, USA; SPIELMANN, Justin, New Mexico Museum of Natural History, Albuquerque, NM, USA; JASINSKI, Steven, State Museum of Pennsylvania, Harrisburg, PA, USA
The Whitaker quarry at Ghost Ranch, Rio Arriba County, New Mexico, USA, is one of the most extensive Late Triassic bonebeds known, yielding hundreds of skeletons of the theropod dinosaur Coelophysis bauri. The quarry also yields the following tetrapod taxa: the sphenodont Whitakersaurus, at least two drepanosaurid taxa, the sphenosuchian Hesperosuchus, a rauisuchian (cf. Postosuchus), the archosaurs Vancleavea and Shuvosaurus (= Effigia) and the phytosaur Redondasaurus. The Whitaker quarry is an unusual Late Triassic paucispecific tetrapod assemblage representing a mass kill of dinosaurs and a limited number of specimens of other tetrapod taxa. Notable is the absence of metoposaurs and aetosaurs, common constituents of Upper Triassic tetrapod assemblages in the American Southwest. Strata that include the Whitaker quarry have been assigned by various workers to the Petrified Forest, Owl Rock or Rock Point formations of the Chinle Group or to the
