European monitor lizards (Anguimorpha, Varanidae, Varanus): New materials and new perspectives.

Abstract

Monitor lizards have a wide current distribution embracing Africa, Asia, and Australia, but
the fossil record indicates that the genus Varanus inhabited Europe at least from the Early
Miocene to the Pliocene. The European fossil record is limited to about 35 localities that
have provided mostly isolated vertebrae. The following European species have been erected
so far: Varanus atticus (Late Miocene; Greece); Varanus deserticolus (Miocene, Hungary);
Varanus hoffmanni (Middle to Late Miocene; Austria, France, Germany, Hungary, Spain,
Moldova); Varanus lungui (Middle Miocene, Moldava); Varanus marathonensis (Late
Miocene to Pliocene; Greece, Hungary); Varanus semjonovi (Late Miocene, Ukraine), and
Varanus tyrasiensis (Middle Miocene, Moldova). With the exception of V. marathonensis, all
these species were erected on the basis of isolated vertebrae that do not provide diagnostic
criteria—and must be therefore considered nomina dubia, potentially being synonyms of
other species—, or not even based on Varanus remains at all. Conversely, V. marathonensis
was described on the basis of cranial material whose description is detailed enough to permit
the recognition of relevant morphological characters.
Here we report unpublished Varanus material recovered from several localities of the late
Middle Miocene local stratigraphic series of Abocador de Can Mata (Vallès-Penedès Basin,
Catalonia, Spain), that is referable to V. marathonensis. Among several fragmentary vertebrae,
two maxillae (IPS50119, IPS50292) show a character which has not been detected in
the 188 specimens of 35 extant Varanus species used for comparison, but which is congruent
with the description of V. marathonensis: the anterodorsal sloping surface of the facial process
is apically wide and concave because it develops a medially directed, broad and slightly
concave lamina. This result opens new perspectives in the taxonomy, phylogeny and biogeography
of the European monitor lizards: V. marathonensis is a valid, diagnosable species, distributed both in western and eastern Europe; and the purported, still unnamed new species
from the Late Miocene of Mytilini (Samos, Greece) should be compared with it.

Full text

November 2011—PROGRAM AND ABSTRACTS 97
Poster Session III (Friday, November 4)
PRESENCE OF PENTACODONTID MAMMALS IN THE EUROPEAN
PALEOCENE
DE BAST, Eric, Royal Belgian Institute of Natural Sciences, Brussels, Belgium; SIGÉ
Bernard, University of Montpellier, Montpellier, France; SMITH, Thierry, Royal Belgian
Institute of Natural Sciences, Brussels, Belgium
A pentacodontid mammal is described from the early Paleocene of Hainin, a Belgian local-
ity that yielded the earliest Cenozoic mammal fauna of Europe (MP1-5 reference-level).
This taxon, represented by a new genus and species is the oldest and smallest European
member of the order Pantolesta. It is also the rst pentacodontid of Europe, a group that was
previously only known from Western North America. The very small new taxon compares
relatively well to Bisonalveus from the North American Tiffanian and Aphronorus from the
North American Torrejonian. Lower molars differ from Bisonalveus in their smaller size,
the more developed precingulid on m1-3, the more lingual position on the hypoconulid
on m3 and the shorter m3 talonid. The Belgian species shares with other pentacodontids a
decreasing size of the molars from m1 to m3 and a relatively low molar crown with rounded
outlines. Both characters differentiate the family from the closely related pantolestids whose
molars are increasingly larger from m1 to m3 and have sharper crowns. Derived pentacodon-
tids such as Pentacodon feature a great size difference between the rst, second and third
molars, whereas the more primitive Bisonalveus displays almost similarly sized molars. The
new pentacodontid that we present here has similarly sized molars, but the m3 talonid is
slightly shorter than in Bisonalveus though not as short as in Pentacodon. The presence of
a pentacondontid in the European Paleocene offers improving evidence for a faunal inter-
change between Europe and North America before the Upper Paleocene.
Poster Session II (Thursday, November 3)
SIGNIFICANT NEW MESOZOIC LOCALITIES FOUND DURING A
PALEONTOLOGICAL RESOURCE INVENTORY OF BLM WILDERNESS LANDS
IN WASHINGTON COUNTY, UTAH
DEBLIEUX, Don, Utah Geological Survey, Salt Lake City, UT, USA; HUNT, Gary, Utah
Geological Survey, Salt Lake City, UT, USA; KIRKLAND, James, Utah Geological Survey,
Salt Lake City, UT, USA; FERRIS-ROWLEY, Dawna, Bureau of Land Management, St.
George, UT, USA; MILNER, Andrew, St. George Dinosaur Discovery Site, St. George, UT,
USA
In 2009, the Omnibus Public Lands Bill was signed into law. In addition to the Paleontologi-
cal Resource Preservation Act, it included the Washington County Wilderness Bill which
designated 129,300 acres of public land administered by the Bureau of Land Management
(BLM) as wilderness. As part of the planning process, the BLM funded the Utah Geological
Survey (UGS) to conduct a paleontological inventory of these wilderness areas. This pro-
vides us with an opportunity for input into critical land-use and management decisions and is
the rst time that paleontological resources have been included in an initial natural resource
inventory for a new public wilderness area.
As a starting point, we created potential fossil yield classication (PFYC) maps for the
wilderness areas using data from UGS 1:24,000 and 1:100,000-scale geological maps of the
region. These maps were used to prioritize paleontological data collection in the eld. Im-
portant fossil-bearing strata in these areas include the Chinle, Moenave, and Kayenta Forma-
tions and, to a lesser degree, the Navajo Sandstone and Carmel Formation. Based on these
geologic units and their proximity to developed areas, the BLM selected the Cottonwood
Canyon, Red Mountain, and Canaan Mountain Wilderness Areas for eld inventory.
Fieldwork began in the fall of 2010 at Red Mountain and Cottonwood Canyon. Numerous
tracksites with tracks attributed to Grallator, Eubrontes, and Brasilichnium were discovered
in the Navajo Sandstone along with several tracksites in the Kayenta Formation. In the
spring of 2011, we focused our work on Canaan Mountain and made numerous signicant
discoveries. A spectacular dinosaur tracksite was discovered in the Whitmore Point Member
of the Moenave Formation. A number of vertebrate bone-bearing localities were found in the
Petried Forest Member of the Chinle Formation including a bonebed, a possible crocodylo-
morph skull, and a partial phytosaur skull.
Symposium 1 (Wednesday, November 2, 11:00 am)
THE ORIGIN OF WINGS
DECECCHI, Alexander, McGill University, Montreal, QB, Canada; LARSSON, Hans,
McGill University, Montreal, QB, Canada
The evolutionary transformation of arms into wings marks one of the most extreme modi-
cations of the tetrapod limb. Flight, in both an aerial and aquatic context, has evolved mul-
tiple times within amniotes. Here we discuss necessary morphological adaptations to create a
viable wing. The three known cases of aerial ight in vertebrates (birds, bats and pterosaurs)
have marked convergences in morphology, physiology and genome size. However, the ques-
tion arises as to which of these changes are necessary and sufcient for ight and which are
later renements. Although ight dynamics are not identical across the three groups, the
physical constraints of ight are. Theropoda present the best transitional series of morpholo-
gies that encompass the entire transition to powered ight. We examined the qualitative and
quantitative trends in morphology inferred necessary for ight throughout the non-avian to
avian phylogenetic history. The early transition period to powered ight is presumed to have
passed through a rapid transition between Simpsonian adaptive zones where dramatic mor-
phological changes occurred. We identify phylogenetic zones where rapid rates of morpho-
logical change are coupled with the origin of distinct allometric relationships and, in turn,
the evolution of a novel pattern of inter- and intra-limb length covariance. Aves has a sig-
nicantly different allometric relationships than non-avian theropods, with longer forelimbs
and shorter hindlimb lengths at a given body size. The relationship between forelimb and
humeral length and mass in volant birds was derived from a large extant avian dataset (>640
specimens), to yield minimal wing skeleton length values to compare to non-avian theropods
and basal birds. All basal birds, including Archaeopteryx, meet this minimal threshold, as do
a few small bodied paravians. This integrated approach suggests ight was present minimal-
ly at the base of Aves, and possibly even Paraves. By associating these nodes to the origin of
powered ight, despite debate on the ecological circumstances of its origin, we can begin to
isolate the modications that are necessary and sufcient to evolve an arm into a wing.
Poster Session II (Thursday, November 3)
CLAVICULAR RING: A NEW METHOD TO ARTICULATE THE PECTORAL
GIRDLE IN STEM-SAUROPODOMORPHS
DELCOURT, Rafael, Museu Nacional / Universidade Federal do Rio de Janeiro, Rio de
Janeiro, Brazil; GRILLO, Orlando, Museu Nacional / Universidade Federal do Rio de
Janeiro, Rio de Janeiro, Brazil; AZEVEDO, Sergio, Museu Nacional / Universidade Federal
do Rio de Janeiro, Rio de Janeiro, Brazil; ROMANO, Pedro, Departamento de Biologia
Animal / Universidade Federal de Viçosa, Viçosa, Brazil
The correct positioning of the pectoral girdle on the ribcage in dinosaurs is difcult to deter-
mine. A horizontal scapula is observed in derived taxa, like birds and higher maniraptorans.
However, in others taxa the coracoids are ventrally positioned and the scapular blade is
inclined steeper than 45º to the horizontal, as can be seen in sauropodomorphs and even in
highly derived ornithischians. Furthermore, it is difcult to determine of the position the
pectoral girdle relative to the anteroposterior axis. As was determined in the research project
“Digital Plateosaurus” this taxon has the anterior edges of the coracoids located below the
last two cervicals. Here we present a new method, the “Clavicular Ring”, to articulate the
pectoral girdle in stem Sauropodomorpha (e.g. Saturnalia tupiniquim) using 3D software for
a more precise positioning. A 3D model of the pectoral girdle, forelimb, anterior vertebra and
ribs of Saturnalia was used in this study. The ribs were articulated to the vertebrae according
to “Digital Plateosaurus”. A semicircle was drawn to represent the incompletely preserved
border of the coracoid. Then the pectoral girdle was cloned and mirrored and the left and
right counterparts were articulated to the ribcage. Based on complete articulated skeletons of
other basal dinosaurs such as Plateosaurus and Eoraptor we could determine that the length
of the articulation between the scapula and the coracoid could be used as the diameter of
a circle (Clavicular Ring) that contacted, ventrally, the coracoids at the articulation for the
clavicles and, dorsally, the ventral surface of the rst dorsal vertebra centrum. In Saturnalia,
after articulating the pectoral girdle using the Clavicular Ring (diameter of 20.36 mm), the
main axis of the scapula formed an angle of 60.13 degrees to the horizontal, which corre-
sponds to the inclination proposed for the scapular blade in Sauropodomorpha. Although this
reconstruction indicates the Clavicular Ring is valid for Saturnalia it is necessary to test it in
other taxa to prove this new methodology.
Poster Session IV (Saturday, November 5)
EUROPEAN MONITOR LIZARDS (ANGUIMORPHA, VARANIDAE, VARANUS):
NEW MATERIALS AND NEW PERSPECTIVES
DELFINO, Massimo, Dipartimento di Scienze della Terra, Università di Torino, Torino,
Italy; ALBA, David, Institut Català de Paleontologia, UAB, Barcelona, Spain; CARMONA,
Raül, Fossilia Serveis Paleontològics i Geològics S.L., Sant Celoni, Spain; LUJÁN, Àngel,
Institut Català de Paleontologia, UAB, Barcelona, Spain; ROBLES, Josep, Fossilia Serveis
Paleontològics i Geològics S.L., Sant Celoni, Spain
Monitor lizards have a wide current distribution embracing Africa, Asia, and Australia, but
the fossil record indicates that the genus Varanus inhabited Europe at least from the Early
Miocene to the Pliocene. The European fossil record is limited to about 35 localities that
have provided mostly isolated vertebrae. The following European species have been erected
so far: Varanus atticus (Late Miocene; Greece); Varanus deserticolus (Miocene, Hungary);
Varanus hoffmanni (Middle to Late Miocene; Austria, France, Germany, Hungary, Spain,
Moldova); Varanus lungui (Middle Miocene, Moldava); Varanus marathonensis (Late
Miocene to Pliocene; Greece, Hungary); Varanus semjonovi (Late Miocene, Ukraine), and
Varanus tyrasiensis (Middle Miocene, Moldova). With the exception of V. marathonensis, all
these species were erected on the basis of isolated vertebrae that do not provide diagnostic
criteria—and must be therefore considered nomina dubia, potentially being synonyms of
other species—, or not even based on Varanus remains at all. Conversely, V. marathonensis
was described on the basis of cranial material whose description is detailed enough to permit
the recognition of relevant morphological characters.
Here we report unpublished Varanus material recovered from several localities of the late
Middle Miocene local stratigraphic series of Abocador de Can Mata (Vallès-Penedès Basin,
Catalonia, Spain), that is referable to V. marathonensis. Among several fragmentary verte-
brae, two maxillae (IPS50119, IPS50292) show a character which has not been detected in
the 188 specimens of 35 extant Varanus species used for comparison, but which is congruent
with the description of V. marathonensis: the anterodorsal sloping surface of the facial pro-
cess is apically wide and concave because it develops a medially directed, broad and slightly
concave lamina. This result opens new perspectives in the taxonomy, phylogeny and bioge-
ography of the European monitor lizards: V. marathonensis is a valid, diagnosable species,

98 © 2011 by the Society of Vertebrate Paleontology
distributed both in western and eastern Europe; and the purported, still unnamed new species
from the Late Miocene of Mytilini (Samos, Greece) should be compared with it.
Poster Session I (Wednesday, November 2)
NEW TAXONOMIC, PALEOBIOGEOGRAPHIC, AND BIOSTRATIGRAPHIC
RECORDS OF FOSSIL SALAMANDERS (CAUDATA) FROM THE HELL CREEK
AND TULLOCK FORMATIONS OF GARFIELD COUNTY, MONTANA
DEMAR, JR., David, University of Washington, Seattle, WA, USA
A recent investigation of the caudate (salamander) fossil assemblages of the latest Creta-
ceous and earliest Paleocene (Lancian and Puercan North American Land Mammal “Ages”
[NALMA], respectively) of Gareld County, northeastern Montana, resulted in the discovery
of new caudate species and paleobiogeographic and/or temporal range extensions of known
salamander taxa. Identications of new Lancian salamanders are based on isolated atlantes
and trunk vertebrae from the lower two-thirds of the Hell Creek Formation. Of particular
interest is the presence of a single trunk vertebra similar in form to the Late Paleocene (Tif-
fanian NALMA) Necturus krausei (Proteidae) of Saskatchewan, Canada. If the phylogenetic
relationships are correct, this specimen would push the known fossil record of proteids
back into the latest Cretaceous. In addition to the identications of new salamander taxa are
specimens previously undescribed from a known fossil sirenid, Habrosaurus prodilatus. The
original description of H. prodilatus from the Campanian (Judithian NALMA) Dinosaur
Park Formation of Alberta, Canada, was based on isolated premaxillae, dentaries, and an at-
las centrum. Here I describe a partial right maxilla (UWBM 93403) and a near complete left
vomer (UCMP 556520) of H. prodilatus from the Hell Creek Formation and compare it to
those of its congener, H. dilatus. Furthermore, trunk vertebrae of the fossil amphiumid, Pro-
amphiuma cretacea, were discovered from three localities of the Tullock Formation. These
specimens represent the rst evidence of unequivocal Paleocene-aged P. cretacea outside of
the temporally-mixed (latest Cretaceous—earliest Paleocene) fossil assemblages of the Bug
Creek Anthills of McCone County, Montana. As the fossil record of latest Cretaceous and
Early Paleocene lissamphibians improves, a better understanding of their diversity and bio-
stratigraphic ranges will ultimately aid in the interpretation of their evolution, extinction, and
recovery, specically during the Cretaceous-Paleogene mass extinction.
Poster Session I (Wednesday, November 2)
DIETARY RECONSTRUCTION OF MIOCENE APES (PRIMATES: HOMINIDAE)
FROM CATALONIA (NE SPAIN) BASED ON DENTAL MICROWEAR
DEMIGUEL, Daniel, Institut Catala de Paleontologia, Barcelona, Spain; ALBA, David,
Institut Catala de Paleontologia, Barcelona, Spain; MOYÀ-SOLÀ, Salvador, Institut Catala
de Paleontologia, Barcelona, Spain
Diet is one of the most important parameters for understanding primate evolution from an
adaptive viewpoint, with signicant implications for dental morphology. Together with
gross wear, the latter can provide many insights into the diet of extinct organisms. Dental
microwear analyses, however, have the potential to reveal more subtle differences in dietary
regimes and feeding behaviors (including seasonal changes) among a great variety of fossil
species. Here we report microscopic wear patterns for ve Middle to Late Miocene homi-
noid taxa from Catalonia (NE Spain), and explore their signicance from a paleodietary
viewpoint. The studied remains were recovered from several sites of the Abocador de Can
Mata series (ACM; MN7+8; Vallès-Penedès Basin), as well as from Teuleria del Firal (TF;
MN9; Seu d`Urgell Basin): Pierolapithecus catalaunicus, Anoiapithecus brevirostris, Dryo-
pithecus fontani, and Hominoidea indet. from ACM; and Hispanopithecus crusafonti from
TF. Molar occlusal facets were inspected at high magnication using environmental SEM,
and microwear scars were recorded and measured. The following four variables were com-
puted: percentage of pits (features with a length/width ratio below 4:1), breadth of scratches
(ratio equal to or above 4:1) and pits, and pit length. Our results indicate the consumption
of a signicant amount of hard items in all the studied taxa except in Hominoidea indet.
However, within this general sclerocarpic behaviour, there are clear differences between
the microwear patterns (particularly in Pierolapithecus, which shows the thickest-enameled
condition). These differences suggest that the studied taxa differed to some extent in their
food preferences, probably reecting their adaptation to somewhat diverging dietary niches
and/or different types of fallback foods. Hominoidea indet. from ACM differs from the other
taxa by a much lower percentage of pits and smaller microwear features, suggesting a greater
reliance on ripe fruits. Our results therefore provide new paleoecological insights into the
Miocene hominoid radiation, during a key period for understanding the origins of the great
ape and human clade.
Poster Session II (Thursday, November 3)
MAMMALIAN ZOOGEOGRAPHY OF THE HIPPARION FAUNA DURING THE
LATE MIOCENE IN CHINA
DENG, Tao, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy
of Sciences, Beijing, China
Late Miocene fossil localities containing Hipparion faunas are numerous in China, espe-
cially in the red clay deposits of northwestern China. In eastern China, they are compara-
tively infrequent and preserved in uvial sandstones or lacustrine marlites. The distribution
of Neogene mammals indicates that the faunas of eastern and western China were obviously
differentiated during the early and middle Miocene, while evidence for this differentiation
is scarce for the late Miocene. Differences between eastern and western China before the
middle Miocene are easily recognized because they have extremely different ecosystems,
i.e., dense forests and open grasslands, respectively. Since the late Miocene, on the other
hand, the dense eastern forests have become sparse woodlands that have more similarities
to the open grasslands in the west, and thus the two are not easily distinguished. However,
the known faunal components and sedimentary features of the late Miocene indicate the
exinstence of a boundary between the eastern and western regions of North China, and
zoogeographical subregions can be recognized. The south sector of this boundary is situated
between Xin’an and Xinxiang in Henan, the middle sector is between Baode and Yushe in
Shanxi, and the north extension is determined to situate between Siziwang and Sonid in
Inner Mongolia. During the late Miocene, the east region of this boundary was humid forest
grassland, persisting since the early Miocene, while the west region was a dry open steppe
that had changed dramatically since the middle Miocene, being strongly affected by the
Tibetan Plateau uplift. This boundary shows that the present Chinese zoogeographical distri-
bution had been established since the Miocene. Based on faunal components, Chilotherium
ourished in the western ecosystem of this zoogeographical division during the late Mio-
cene, and it became extremely dominant in the community. The second largest group was
various grassland hyenas. They composed a particular endemic fauna in China. In the faunas
to the east of this boundary, Chilotherium was very rare, while Hipparion was dominant.
Poster Session III (Friday, November 4)
MAMMALIAN NICHE CONSERVATION THROUGH DEEP TIME
DESANTIS, Larisa, Vanderbilt University, Nashville, TN, USA; BEAVINS TRACY, Rachel,
Vanderbilt University, Nashville, TN, USA; KOONTZ, Cassandra, Vanderbilt University,
Nashville, TN, USA; ROSEBERRY, John, Vanderbilt University, Nashville, TN, USA;
VELASCO, Matthew, Vanderbilt University, Nashville, TN, USA
Climate change is currently altering the distribution of species, causing plants and animals to
move north or to higher elevations with current warming trends. Bioclimatic models predict
the distribution of species based on extant realized niches and often assume that ecological
niches are maintained over long time scales. Recent work has demonstrated that niche con-
servatism operates above the species level during the Quaternary. Here, we build upon this
work by evaluating if niches are conserved at the family level through deep time, from the
Eocene to the Pleistocene. We analyzed the occurrence of all mammalian families (with >3
occurrences in the Paleobiology Database) in the continental USA, calculating range area,
range area rank, and range polygon centroids during each respective epoch. Range areas gen-
erally increase from the Eocene to the Miocene, decrease from the Miocene to the Pliocene,
and increase from the Pliocene to Pleistocene, while range area ranks are largely conserved.
Furthermore, centroids demonstrate a southeastern shift from the Eocene through the Pleisto-
cene. These changes may correspond to major environmental events and/or climate changes
such as the Miocene grassland expansion and cooling since the mid-Miocene climatic opti-
mum. High statistical concordance between rank orders across time demonstrates that niches
are conserved at the family level and further supports the idea that niche conservation at
higher taxonomic levels is controlled by life history traits. Furthermore, families containing
megafauna and/or terminal Pleistocene extinction victims did not incur signicantly greater
declines in range area rank changes then families containing only smaller taxa and/or only
survivors, from the Pliocene to Pleistocene. Similarly, the time depth of a family does not af-
fect range area rank changes. These results demonstrate the resilience of families to climate
and/or environmental change in deep time, the absence of terminal Pleistocene “extinction
prone” families, and the subsequent importance of conserving biodiversity at higher taxo-
nomic levels to allow for greater exibility to maintain existing niches.
E&O Poster Session
VERTEBRATE PALEONTOLOGY AS THE CORNERSTONE OF A FIRST-YEAR
COLLEGE SEMINAR
DEWAR, Eric, Suffolk University, Boston, MA, USA; MACELI, Ashley, Suffolk University,
Boston, MA, USA; PIETRANTONIO, Heather, Suffolk University, Boston, MA, USA
Many colleges and universities require incoming students to complete a rst-year seminar to
introduce them to the rigors of college-level work. At Suffolk University, the seminars are
reading- and writing-intensive courses centered around topics chosen by faculty. Last year a
new freshman seminar entitled “Vertebrate Fossils and Evolution” was developed with verte-
brate paleontology as its organizing theme. Of the 20 students who chose this seminar, only
six were biology majors—the rest came from across the curriculum. Given a wide range of
experience in science and little familiarity with the fossil record of vertebrates, the most im-
portant goal of the seminar was for the students to learn to construct knowledge and critique
scientic arguments, in this case focused on the paleobiology and evolution of vertebrates.
We attempted to reach this goal with a mix of lectures, discussions, eld trips, and small-
group projects. To get started with a diverse group, we needed to show how the scientic
process works as applied to fossils. Foundational lectures about paleontological methods,
taphonomy, and the relationships of the major taxa early in the semester gave way to read-
ings from the primary literature about terrestrialization, the biomechanics of locomotion, and
the mammalian radiations, among other topics.
Students practiced the construction of knowledge and making scientic arguments by ob-
serving exhibits of vertebrate fossils at local museums. For example, they learned to nd
and score dozens of morphological characters, and then try to see if they could nd effective
synapomorphies themselves. Working with fossils themselves was much more effective
than lectures for the students to learn both the taxa and the pitfalls of constructing their own