THE QUALITY OF THE PTEROSAUR FOSSIL RECORD

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JVP 29(3) September 2009—ABSTRACTS 1A
JOURNAL OF VERTEBRATE PALEONTOLOGY
VOLUME 29, SUPPLEMENT TO NUMBER 3
September 2009
ABSTRACTS OF PAPERS
SIXTY-NINTH ANNUAL MEETING
SOCIETY OF VERTEBRATE PALEONTOLOGY
AND THE
FIFTY-SEVENTH SYMPOSIUM OF VERTEBRATE PALAEONTOLOGY
AND COMPARATIVE ANATOMY (SVPCA)
UNIVERSITY OF BRISTOL
BRISTOL, UK
SEPTEMBER 23-26, 2009
HOST COMMITTEE
Michael Benton, Emily Rayfield, Phil Anderson, Paul Barrett, Phil Donoghue, Pam Gill, Tom Kemp,
Liz Loeffler, Angela Milner, Dave Norman, Remmert Schouten
EXECUTIVE COMMITTEE
Blaire VanValkenburgh, President, Catherine Badgley, Past-President; Philip Currie, Vice-President;
Christopher A. Brochu, Secretary; Ted Vlamis, Treasurer; Ana Baez, Member-at-Large;
Michael Gottfried, Member-at-Large; Julia Clarke, Member-at-Large
SYMPOSIUM CONVENORS
Kenneth Angielczyk, Robert Asher, Richard Butler, Patrick Druckenmiller, Gareth Dyke,
Randall Irmis, Christian Kammerer, Max Langer, Larry Martin, Erin Maxwell, Johannes Müller
PROGRAM COMMITTEE
Jason Head, Chair; Jonathan Bloch, Matthew Carrano, Kerin Claeson, Kristi Curry Rogers,
Ted Daeschler, David Fox, Nadia Fröbisch, Anjali Goswami, Michael Gottfried, Johannes Müller,
Emily Rayfield, William Sanders, Mary Silcox, Rebecca Terry

JVP 29(3) September 2009—ABSTRACTS 27A
10:45 Beck, R. RESOLVING THE HIGHER-LEVEL PHYLOGENY OF MARSUPIALIA USING MOLECULAR
AND MORPHOLOGICAL DATA: PROGRESS, PROBLEMS AND PROSPECTS
11:00 Bickelmann, C., Müller, J., Du, J., Chang, B. INFERRING EARLY MAMMALIAN PALEOBIOLOGY FROM
VERTEBRATE VISUAL PIGMENTS
11:15 Tucker, A. EVO-DEVO OF THE MIDDLE EAR: FINDING HOMOLOGIES BY LINKING MORPHOLOGY
WITH GENE EXPRESSION
11:30 Meredith Smith, M., Johanson, Z. EVOLUTION OF JAWS AND TEETH
11:45 Buchholtz, E. EVOLUTIONARY PATTERNS OF VERTEBRAL VARIATION
12:00 Galis, F., Metz, J. EVOLUTIONARY NOVELTIES: THE MAKING AND BREAKING OF PLEIOTROPIC
CONSTRAINTS
TECHNICAL SESSION X
WILLS MEMORIAL BUILDING, GREAT HALL
MODERATORS: David Unwin, David Norman
8:00 Whiteside, D., Marshall, J. FAUNAL SUCCESSION OF THE LATE TRIASSIC-EARLY JURASSIC
TERRESTRIAL TETRAPOD ASSEMBLAGES FROM THE FISSURE DEPOSITS OF SOUTH WESTERN
BRITAIN
8:15 Xu, X., Hu, D. AN EXCEPTIONALLY WELL PRESERVED JURASSIC TERRESTRIAL FAUNA IN
NORTHEASTERN CHINA
8:30 Andres, B. THE QUALITY OF THE PTEROSAUR FOSSIL RECORD
8:45 Osi, A. FEEDING RELATED CHARACTERS IN BASAL PTEROSAURS: IMPLICATIONS FOR JAW
MECHANISM, DENTAL FUNCTION AND DIET
9:00 Unwin, D., Lü, J. BRIDGING A MAJOR EVOLUTIONARY GAP: A LONG-TAILED PTEROSAUR WITH A
PTERODACTYLOID SKULL
9:15 Ibrahim, N., Unwin, D., Zouhri, S., Martill, D. DIVERSITY AND EVOLUTIONARY SIGNIFICANCE OF
PTEROSAURS FROM THE EARLY LATE CRETACEOUS OF MOROCCO
9:30 Vullo, R., Marugán-Lobón, J., Buscalioni, Á., Moratalla, J. THE FIRST TAPEJARID PTEROSAUR FROM
EUROPE
9:45 Kellner, A., Wang, X., Tischlinger, H., Hone, D., Meng, X. THE SOFT TISSUE OF JEHOLOPTERUS
(PTEROSAURIA, ANUROGNATHIDAE) AND THE STRUCTURE OF THE PTEROSAUR WING
MEMBRANE
10:00 BREAK
10:15 Bennett, S. THE PECTORAL GIRDLE OF PTERODACTYLUS ANTIQUUS-EVOLVING TOWARD THE
ADVANCED CONDITION
10:30 Marty, D. SEDIMENTOLOGY, TAPHONOMY, AND ICHNOLOGY OF LATE JURASSIC DINOSAUR
TRACKS FROM THE JURA CARBONATE PLATFORM (NW SWITZERLAND): INSIGHTS INTO
THE TIDAL-FLAT PALAEOENVIRONMENT AND DINOSAUR DIVERSITY, LOCOMOTION, AND
PALEOECOLOGY
10:45 Smith, N., Turner, A., Irmis, R., Nesbitt, S. PATTERNS IN EARLY DINOSAUR BIOGEOGRAPHY
REVEALED BY QUANTITATIVE METHODS OF ANCESTRAL GEOGRAPHIC RANGE
RECONSTRUCTION
11:00 Stevens, K., Wills, E. NON-PARASAGITTAL YET EFFICIENT: THE ROLE OF THE PECTORAL GIRDLES
AND TRUNK IN THE WALK OF TRICERATOPS AND APATOSAURUS
11:15 Burns, M. MORPHOLOGY, HISTOLOGY, AND STRUCTURAL MECHANICS OF ANKYLOSAUR
OSTEODERMS: IMPLICATIONS FOR FUNCTION AND SYSTEMATICS
11:30 Moratalla, J., Marugán-Lobón, J. ASSESSING DINOSAUR ICHNO-VARIABILITY WITH GEOMETRIC
MORPHOMETRICS. THE ORNITHOPOD TRACKS FROM THE CAMEROS BASIN (LOWER
CRETACEOUS, SPAIN) AS A CASE STUDY

JVP 29(3) September 2009—ABSTRACTS 55A
internal chambers and delimiting the depression itself. This morphology was consistently
found in several other goniopholidid specimens. In all living crocodilians, the MNF are
directly related to dome pressure receptors (DPRs), integumentary sensory organs present on
the skin surface. DPRs are innervated by the trigeminal nerve and are sensitive to pressure
differences in the air-water interface. As sensory organs, the DPRs are linked to orientating
behavior towards mechanical stimuli in Alligator; a behavior is completely abolished
when the DPRs are covered. Based on the evidence provided by the extant phylogenetic
bracket, the maxillary depressions of Goniopholis (and possibly other goniopholidids) were
composite sensory organs, equipped with densely-packed DPRs. These organs constituted
powerful sensors used to find and capture prey at the air-water interface, and indicate the
preferential strategy and medium for prey capture in the extinct Goniopholididae.
Technical Session X, Friday 8:30
THE QUALITY OF THE PTEROSAUR FOSSIL RECORD
ANDRES, Brian, Yale Department of Geology and Geophysics, New Haven, CT, USA
Recently, two independent studies of the pterosaur fossil record have been presented with
largely contradictory results. These studies primarily assessed either relative completeness
or bias in the fossil record of pterosaurs. Ideally, aspects of each should be incorporated
into the measurement and the requirements of the particular method to use the fossil record
should be referenced. Along these lines, it has been put forward that with random sampling
the fossil record of a taxon must be very incomplete before the phylogenetic inference is
affected but with biased sampling, phylogenetic analyses can be influenced at lower levels
of completeness. To assess the quality of the pterosaur fossil record within this framework,
a distinct form of taxon jackknifing was employed using a new phylogeny of pterosaur
relationships. Pterosaur species were placed into categories based on known biases in the
fossil record, they were sequentially removed from these categories, the resulting matrices
analyzed and their similarity measured to the original analysis, and the results compared to
analyses with random species removal. Over the entire range and at low and high amounts of
taxon removal, removal of species based on potential biases were not significantly different
from random sampling. At intermediate levels of taxon removal (15-55%), removal of
terrestrial species, larger species, younger species, and more recently described species had
less impact on the phylogenetic analysis than removal of marine species, smaller species,
and earlier described species. Removal based on ontogenetic stage, and older species were
not significantly different from random removal. Removal of species based on relatively
more or less species occurring in the same formation were not significantly different from
one another, but both contained significantly more of the original phylogenetic structure than
random removal. It may be possible to measure the quality of the pterosaur fossil record in
such a manner by referencing how many species must be removed before biases begin to
affect their phylogenetic results.
Poster Session IV, (Saturday)
SEXUAL DIMORPHISM AND BODY-SIZE CLINES IN GAZELLOSPIRA
TORTICORNIS
ANDRES , Maria, Universidad de Zaragoza, Zaragoza, Spain; ALCALDE, Gema, Museo
Nacional de Ciencias Naturales-CSIC, Madrid, Spain; AZANZA, Beatriz, Universidad
de Zaragoza, Zaragoza, Spain; HERNÁNDEZ FERNÁNDEZ, Manuel, Universidad
Complutense, Madrid, Spain; ALBERDI, María Teresa, Museo Nacional de Ciencias
Naturales-CSIC, Madrid, Spain
The strong heterogeneity on size exhibited by the euroasian Pliocene antelope Gazellospira
torticornis has lead different authors to set out two hypotheses: there were more than
one species in the European Pliocene or the existence of a temporal body-size cline
within a single species, which presented a strong trend towards size reduction along the
Villafranchian. Recently sexual dimorphism has been suggested as an explanation for the
differences in size of the metapodials of this fossil bovid. Moreover, studied samples are not
often very representative and the possibility of a differential preservation between males and
females among localities also exists. In order to clarify this issue, we have applied a tested
model which explain the sexual dimorphism in four captive-bred North African bovids, three
gazelles (Nanger dama, Gazella dorcas and Gazella cuvieri) and a caprine (Ammotragus
lervia). All these species displayed sexual dimorphism on size and morphology. Particularly
the biggest ones, N. dama and A. lervia, show sexual differences in all skeletal elements and
even in teeth. Since Gazellospira is even larger, a similar pattern could be expected. Data of
G. torticonis from several European localities have been included in the statistical analyses
(PCA) that have been carried out. Our results confirm a comparable pattern of sexual
dimorphism in N. dama, A. lervia and G. torticornis. Clearly separated sexual groups have
been found, among others, for metapodials, humerus, radius, and astragali and, in a lesser
grade, for teeth. Besides, a decrease on body-size has been also observed from the MN16 to
MN17 samples, supporting the temporal cline hypothesis.
Technical Session XVII, Saturday 2:15
A RE-EVALUATION OF THE DICYNODONTS (THERAPSIDA, ANOMODONTIA)
OF THE PERMIAN RUHUHU FORMATION (SONGEA GROUP, RUHUHU BASIN),
TANZANIA
ANGIELCZYK, Kenneth, The Field Museum, Chicago, IL, USA; SIDOR, Christian,
University of Washington, Seattle, WA, USA; SMITH, Roger, Iziko South African Museum,
Cape Town, South Africa; STEYER, Jean-Sebastién, CNRS-MNHN Dept. Histoire de la
Terre , Paris, France; GOSTLING, Neil, SUNY Oswego, Oswego, NY, USA
Dicynodont therapsids have been known from the Upper Permian of the Ruhuhu Basin,
Tanzania, since the 1930’s. Nearly all of these specimens have been collected in the Usili
Formation, which is generally regarded as Late Permian in age, although scattered reports
place Endothiodon in the underlying Ruhuhu Formation. Field observations from 2007 and
2008, as well as the preservation of the supposed Ruhuhu Formation Endothiodon material
strongly suggest that it actually originated in a conglomerate layer at the base of the Usili.
Therefore, no dicynodonts are definitively known from the Ruhuhu Formation. In 2008,
our field team made a new collection of fossils from the Ruhuhu Formation. Noteworthy
among this material are the first dinocephalian remains from Tanzania, which suggest a
Middle Permian age for the formation, as well as fragmentary material representing the
oldest known Tanzanian amphibian. In addition, we collected a small, articulated snout and
anterior lower jaw that appears to represent the first dicynodont from the Ruhuhu Formation.
The dentition of the specimen is unique. A row of five teeth are located in a medial to
lateral-trending row on the maxilla, and are flanked laterally by a shelf similar to that in
Endothiodon. In their unworn state, these teeth are triangular in lateral view, procurved,
and bear a strong groove on their anterior surface, but their pointed tips are lost with wear.
Posterior and lateral to this tooth row are two larger, rounded teeth potentially in the process
of replacement. The structure of the maxilla and vomer, and the placement of the tooth row,
suggest possible affinities with endothiodontid dicynodonts. Analysis of high-resolution CT
data is currently underway to collect additional data on the palatal and jaw morphologies of
this specimen, which in turn hold the potential to further clarify its phylogenetic position.
The unexpected nature of the Ruhuhu Formation fauna indicates that further collecting from
this unit is needed, and that it has the potential to provide an important new window into
Middle Permian tetrapod communities.
Poster Session III, (Friday)
FUNCTIONAL ANATOMY OF THE CERVICAL VERTEBRAE OF THE
SCIMITAR-TOOTH CAT MACHAIRODUS APHANISTUS
ANTÓN, Mauricio, Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain; SALESA,
Manuel, Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain; TURNER, Alan,
Liverpool John Moores University, Liverpool, United Kingdom; PASTOR, Juan, Facultad de
Medicina, Universidad de Valladolid, Valladolid, Spain; MORALES, Jorge, Museo Nacional
de Ciencias Naturales-CSIC, Madrid, Spain
The cervical vertebrae play an essential role in the hypothetical models of the predatory
behavior of sabertoothed cats. Derived members of the machairodontine tribes Smilodontini
and Homotherini share the possession of strong, elongated cervicals with prominent
processes for muscle insertion, traits that have been interpreted as adaptations for a derived
type of killing bite known as the Canine Shear-Bite. These features are well known in
the Plio-Pleistocene homotherine genus Homotherium, but have remained undescribed
in the basal genus of the tribe, the Miocene-aged Machairodus. The study of abundant,
well preserved cervical vertebrae of Machairodus aphanistus from the Spanish fossil site
of Batallones-1 (Upper Vallesian, MN 10) allows to characterize the morphology of the
neck in this early species. We compare the vertebrae of M. aphanistus with those of later
homotherine genera Amphimachairodus and Homotherium, as well as with those of other
machairodontine and feline cats. We also gather data about muscle insertion placement
from dissections of extant felids. Our comparisons show that the atlas-axis complex of M.
aphanistus is intermediate in morphology between that of felines and that of Homotherium.
The posterior cervicals, on the other hand, are surprisingly similar to those of Homotherium
in the degree of elongation of the centra and in the development of processes for muscle
attachment. This combination of features reveals a mosaic evolution of anatomical
adaptations for the Canine Shear-Bite, but also raises questions about the polarity of
characters such as the elongation of posterior cervical centra, since it cannot be ruled out that
the cervicals of modern cats are shortened relative to those of an ancestral felid. In functional
terms, the combination of feline and machairodontine cervical features in M. aphanistus
indicates an ability comparable to that of Homotherium for positioning the head for biting
precise points in the body of large ungulates, and to hold it very strongly in any position, but
also a lesser ability to recruit atlanto-axial muscles in the depression of the head, and thus a
less efficient version of the Canine Shear-Bite.