program and abstracts

Supplement to the online Journal of Vertebrate Paleontology October 2013

PROGRAM AND ABSTRACTS

Westin Bonaventure Hotel & Suites • Los Angeles, CA, USA • October 30 – November 2, 2013 ISSN 1937-2809

temporal bone of latest Miocene to earliest Pliocene age (5.0–6.2 Ma; Black Rock Sandstone, Beaumaris, Victoria, Australia). NMV P160399 has been referred to in print as a monachine, which is confirmed here by phylogenetic analysis, resolving it as an early monachine stemward of Mirounga (elephant seals) + Lobodontini (Recent Antarctic phocids plus extinct Acrophoca and Homiphoca). The second specimen is a cranium, CM (Canterbury Museum) Zfa333, of uncertain middle Miocene to Pliocene age (3.0–?12.0 Ma; Greta Siltstone, Motunau, South Island, New Zealand). CM Zfa333 is also a monachine, possesses more derived morphology than Monachus and NMV P160399, but lacks apomorphies of Lobodontini. Neither of the Australasian phocids appears to have close relationships with (1) approximately coeval fossil monachines described from Peru and South Africa; or (2) living Lobodontini of the Southern Ocean. Australasian fossil phocids were surprisingly disparate from those occurring elsewhere on the margins of the Southern Ocean during the Mio-Pliocene. These archaic phocids may represent a hitherto unrecognized austral dispersal and diversification of early monachine seals that preceded the pagophilic Lobodontini of present day Antarctica. Poster Session I (Wednesday, October 30, 2013, 4:15 - 6:15 PM) NEW LIZARDS FROM THE EARLY EOCENE VASTAN LIGNITE MINE OF INDIA FOLIE, Annelise, Royal Belgian Institute of Natural Sciences, Brussels, Belgium; RANA, Rajendra S., H.N.B. Garhwal University, Srinagar, India; AUGÉ, Marc, Muséum National d’Histoire Naturelle, Paris, France; KUMAR, Kishor, Wadia Institute of Himalayan Geology, Dehradun, India; SMITH, Thierry, Royal Belgian Institute of Natural Sciences, Brussels, Belgium The lower Eocene (Ypresian) Cambay Formation at Vastan Lignite Mine in Gujarat, western India, has yielded a rich vertebrate assemblage including the earliest modern mammals and oldest birds of the Indian subcontinent. Among the herpetological faunas, snakes, lizards and amphibians are abundant, but, strangely, lizards are only represented by agamids. Here we describe the agamid assemblage based on numerous, diverse and well-preserved dentaries, premaxillaries, and maxillaries. At least four taxa are present at Vastan. Vastanagama susanae is characterized by dentaries with a large symphyseal facet, three anterior pleurodont teeth followed by acrodont teeth presenting a main cusp bordered by two lateral crests; the teeth increase in size posteriorly toward the coronoid process. Tinosaurus indicus exhibits a subdental ridge between the tooth row and the Meckelian canal, pleurodont symphyseal teeth including one that can be caniniform, and acrodont and tricuspid posterior teeth with poorly differentiated lateral cusps. Two other taxa represent two new genera and species. The first taxon presents multicuspid acrodont teeth with the main cusp surrounded by two or three progressively smaller lateral cusps. The second taxon presents pleurodont anterior teeth followed by a few acrodont teeth and ending with three or four subacrodont teeth near the coronoid process. Our results confirm that Agamidae (assigned to the Acrodonta) is the only lizard group present at Vastan, whereas many other groups are already present in the Early Eocene on the other continents. Agamidae is considered to have had a Gondwanan origin, with 52 genera and 420 species of extant agamids known from Asia, Australia, Africa and a few from Southern Europe. The oldest occurrence of formally recognized Acrodonta is found in the Jurassic of India. Other fossil agamids are known in the Upper Paleocene of Kazakhstan, Paleocene and Eocene of China, Early Eocene of Europe, Eocene of North America, and Middle Eocene of Pakistan. The diversity of the agamids in India and the absence of other lizard groups at Vastan tentatively support the Out-ofIndia hypothesis for agamids. Technical Session XV (Saturday, November 2, 2013, 11:15 AM) LATE OLIGOCENE TUSKED DOLPHIN FROM THE WAITAKI REGION, NEW ZEALAND FORDYCE, Robert, University of Otago, Dunedin, New Zealand; AGUIRREFERNÁNDEZ, Gabriel, University of Otago, Dunedin, New Zealand; LOCH, Carolina, University of Otago, Dunedin, New Zealand The Oligocene early radiation of the Neoceti involved major increases in taxonomic, structural, and ecological diversity amongst Odontoceti and Mysticeti. Some fossils are putative stem members of living families, but others defy easy phylogenetic placement, and many have presented unexpected or unusual morphologies. One such fossil is an unnamed late Oligocene dolphin from Tokarahi, Waitaki district of New Zealand. The source horizon is transitional Kokoamu Greensand-Otekaike Limestone, about 26 Ma (Sr/Sr and foraminiferal dates), representing a mid-shelf setting. OU 22397 (Geology Museum, University of Otago) includes a skull (condylobasal length 584 mm), tympanoperiotics, and a mandible. The elongate (386 mm) narrow rostrum is markedly flattened, with elongate distal premaxillae (~82 mm) and an open shallow mesorostral groove. The rostrum carries gracile, horizontally-projecting, tusk-like incisors to 65 mm long, which grade back to less procumbent and increasingly vertical maxillary teeth. The latter are polydont (n = 13) and emergent, with prominent diastemata. Posteriorly, the tooth crowns become high, bucco-lingually flattened, and triangular, with vestigial posterior denticles. The cranium is low, with a prominent flat vertex and shallow facial fossae, and is roughly symmetrical. The intertemporal constriction is marked. Pterygoid sinuses are restricted to the basicranium. Because of its associated skull, mandible and earbones, OU 22397 is the key to identifying three other less-complete late Oligocene New Zealand dolphins as related closely (OU 22126 and other specimens, representing 3 species, from the Kokoamu Greensand and Otekaike Limestone). A cladistic analysis (67 taxa, 311 characters, run with TNT) gave a single tree of 2231 steps, with OU 22397 and OU 22126 in a clade along with un-named tusked species from the northeast Pacific including USNM 205491 (US National Museum; Oligocene, Oregon). In turn, the tusked dolphins form the sister taxon to Simocetus in a clade that includes, as progressively basal members, Agorophius, Patriocetus, and Waipatia. The New Zealand tusked dolphins have been identified tentatively as Dalpiazinidae, but whether they are truly close to the fragmentary, longirostral, Miocene Italian Dalpiazina

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ombonii is uncertain. The scattered phylogenetic occurrences of gracile procumbent tusks amongst stem and crown odontocetes (e.g. dalpiazinids, Waipatia, Squalodelphinidae, and Kentriodon) suggest that the tusks are homoplastic structures. Technical Session XI (Friday, November 1, 2013, 1:45 PM) PROCESSED-BASED ESTIMATES OF STRATIGRAPHIC COMPLETENESS: IMPLICATIONS FOR THE ALLUVIAL VERTEBRATE FOSSIL RECORD FOREMAN, Brady, University of Minnesota, Minneapolis, MN, United States, 55414; HAJEK, Elizabeth, Penn State University, University Park, PA, United States; STRAUB, Kyle, Tulane University, New Orleans, LA, United States Sedimentation within alluvial stratigraphic sequences exerts a first order control on the completeness of the terrestrial fossil record. Discontinuous sedimentation results in discontinuous preservation of fossil material and, in turn, a discontinuous record of the history of life. Yet, recent field and experimental stratigraphic studies suggest there is a characteristic timescale over which deposition may be considered continuous. In fluvially dominated basins this timescale is controlled by the long-term aggradation rate and the topographic ‘roughness’ and kinematics of the paleo-landscape. Under constant climate, tectonic, and eustatic conditions internally generated (i.e., autogenic) landscape dynamics set the timescale at which spatially non-uniform sedimentation patterns are compensated and the basin filled evenly. We propose this timescale provides 1) an estimate on the finest temporal resolution that the fossil record may be considered ‘complete’, 2) a greater understanding of spatiotemporal variability in time-averaging within fossil sites, 3) a means to assess secular shifts in sampling density, and 4) a natural bin size to examine rates of taxonomic turnover, diversity, and evolutionary changes. We illustrate this approach using the early Paleogene mammalian record in the Bighorn Basin of northwest Wyoming (U.S.A.). Here, alluvial strata of the Fort Union and Willwood formations display repetitive packages of amalgamated channel belt deposits and overbank sequences of avulsion deposits with variably developed paleosols. Based on subsidence histories and reconstructed paleo-topography, a best case scenario estimate suggests sedimentation may be considered continuous at ~10 kyr and longer. Binning fossil sites with this new measure reveals that ~16% of the mammal record is represented by at least one fossil locality on the 10 kyr timescale and ~73% on the 100 kyr timescale. Bins near the Paleocene-Eocene boundary represent a near ‘continual’ sampling of taxa and highest density of localities per bin. We also assess how secular changes in tectonic subsidence and transient climate change events may have affected basin-scale fossil preservation patterns. Overall this process-based approach enhances chronostratigraphic frameworks, and allows for more detailed evaluation of evolutionary, ecological, and taphonomic uncertainty. Poster Session II (Thursday, October 31, 2013, 4:15 - 6:15 PM) A SMALL SAUROPOD DINOSAUR (HAPLOCANTHOSAURUS?) FROM THE LOWER MORRISON FORMATION (UPPER JURASSIC) OF CENTRAL COLORADO FOSTER, John, Museum of Western Colorado, Grand Junction, CO, United States, 81502 Remains of a dinosaur collected from the Rocky Mountains of central Colorado (north of the Elk Range, Pitkin County) are likely those of the small, rare sauropod Haplocanthosaurus. The remains (Museum of Western Colorado specimen MWC 8028) are from the lower third of the Upper Jurassic Morrison Formation, at a level similar to the Cleveland Museum Delfs Quarry at Garden Park, Colorado. The new specimen consists of four dorsal centra, five partial ribs, the sacrum, five caudal vertebrae, three chevrons, and five partial neural spines. The dorsal centra possess pleurocoels and fossae and are not strongly camerate, sacral neural spines are characterized strong posterior inclination, the anterior caudal vertebrae are moderately amphicoelous to slightly procoelous (the differences between vertebrae likely being preservational), are anteroposteriorly short for their diameters, and have squarish ventral surfaces, straight sides, and pneumatic(?) excavations of the dorsal surfaces of the centra, apparently from the ventral surfaces of the neural canals, the chevron facets are large, the five isolated, nonbifurcate neural spines appear to belong to dorsal vertebrae. The neurocentral sutures and caudal ribs are fused, indicating an adult animal, but the sacral and anterior caudal vertebrae are small, only 17–20 cm in diameter. Various morphological aspects prevent definitive identification of the material as any of the common Morrison diplodocid sauropods (Diplodocus, Barosaurus, or Apatosaurus); Camarasaurus and Brachiosaurus are less readily eliminated as possibilities but in their adult dorsal size and morphology do not match MWC 8028. The specimen appears generally similar in size and vertebral morphology to Haplocanthosaurus priscus (Carnegie Museum specimen CM 572), and the stratigraphic level of the quarry is consistent with the likelihood that the material belongs to this species. MWC 8028 is similar in morphology but slightly smaller than Utah Field House of Natural History specimen FHPR 1106 (Haplocanthosaurus sp.), and the sacral and caudal vertebrae are ~50% smaller than Cleveland Museum of Natural History specimen CMNH 10380 (H. delfsi). If confirmed as Haplocanthosaurus by a more complete dorsal vertebra, MWC 8028 will represent just the tenth specimen and the seventh locality for this sauropod in the Morrison Formation.

© 2013 by the Society of Vertebrate Paleontology