Mammal-Eating Microraptor and 3-D Theropod Pelvis Dataset

[bh480@scn.org]

From: Ben Creisler
bh480@scn.org

Now that the embargo on abstracts for the 2010 SVP 
meeting is over by at least a week, I assume it's OK to 
cite some of the items. They will show up in BIOSIS, the 
Zoological Record, and other databases in the very near 
future in any case. I have a more comprehensive list in 
the works, but here are a few of note plus another recent 
item that might be of interest.

SVP Abstracts 2010 (selection)

THE WINGED NON-AVIAN DINOSAUR MICRORAPTOR FED ON MAMMALS: 
IMPLICATIONS FOR THE JEHOL BIOTA ECOSYSTEM
LARSSON, Hans, Redpath Museum, McGill University, 
Montreal, QB, Canada; HONE, 
David, Institute of Vertebrate Paleontology and 
Paleoanthropology, Beijing, China; 
DECECCHI, T. Alexander, Redpath Museum, McGill 
University, Montreal, QB, Canada; 
SULLIVAN, Corwin, Institute of Vertebrate Paleontology 
and Paleoanthropology, Beijing, 
China; XU, Xing, Institute of Vertebrate Paleontology and 
Paleoanthropology, Beijing, 
China 
Direct evidence for predator-prey interactions in the 
fossil record are rare. Dietary regimes and trophic 
interactions within extinct communities are usually 
inferred based on indicators such as body size, tooth 
shape, and coprolites. While these lines of evidence are 
useful, only gut contents provide direct evidence for an 
individual?s diet. We report here the first gut contents 
of a non-avian paravian within the small feathered 
theropod Microraptor. The holotype of Microraptor 
zhaoianus includes fragments of articulated dorsal 
vertebrae with regularly spaced ribs. Between the left 
and right ribs is preserved an articulated foot of a 
mammal. Other bones are also present and may include 
possible cranial, limb and axial elements of the mammal. 
The morphology of the foot is most similar to Eomaia and 
Sinodelphys, although this specimen lacks the level of 
arboreal adaptations seen in those taxa. The foot is 
relatively long, with a shortened first metatarsal and 
elongate phalanges possessing a phalangeal ratio of 
around 1. The preserved unguals are moderately recurved, 
the phalanges are straight and the ratio of proximal to 
distal phalanges does not indicate a dedicated arboreal 
lifestyle but suggests the animal was most likely 
scansorial. Body size and mass of the Microraptor and 
mammal specimens were calculated from metric comparisons 
to closely related taxa. The Microraptor specimen is 
estimated to have a snout-vent length of 140 - 150 mm and 
a body mass of between 100 and 150 g. The mammal is 
estimated to have had a snout-vent length of 
approximately 80 mm and a body mass of 20 - 25 g. We 
compare these values to those among extant tetrapod 
predators and prey. This new find provides valuable 
information regarding species interactions and trophic 
relationships within the Jehol Biota. This discovery, 
combined with other recent finds from these deposits, 
permits a more accurate reconstruction of the food web 
structure of this Lower Cretaceous fauna. These data 
suggest that unlike the earliest birds, which were either 
insectivorous or herbivorous (e.g. Archaeopteryx, 
Jeholornis), Microraptor was an active predator of agile, 
small-bodied vertebrates.


FIRST OCCURRENCE OF A TYRANNOSAURID (DINOSAURIA, 
THEROPODA) FROM THE NESLEN FORMATION (LATE CRETACEOUS), 
BOOK CLIFFS AREA, UTAH
THOMSON, Tracy, University of Utah, Salt Lake City, UT, 
USA; IRMIS, Randall, 
University of Utah, Salt Lake City, UT, USA 
Although rich Campanian dinosaur assemblages are known 
from southern Utah, specimens are extremely rare from 
Campanian strata in central and eastern Utah that were 
closer to the paleoshoreline of the Western Interior 
Seaway. We report the discovery of a theropod dinosaur 
partial hindlimb from the Book Cliffs area northeast of 
Green River, Utah. The specimen was recovered from just 
beneath the Palisade Coal Zone in the Neslen Formation 
(Mesa Verde Group), which is dated to the mid-Campanian 
(75.19 ±0.28 Ma) based on its stratigraphic location 
within the Didymoceras nebrascense ammonite zone. This 
stratigraphic interval correlates with the lower 
Kaiparowits Formation of southern Utah, the Dinosaur Park 
Formation of Alberta, and the Judith River and Two 
Medicine formations of Montana. The specimen comprises a 
partial fibula, the distal half of metatarsal II, and a 
complete metatarsal IV. The arctometatarsalian condition 
of the pes indicates its placement in the theropod clade 
Coelurosauria, and the specimen can be assigned to the 
clade Tyrannosauridae based on the presence of 
unambiguous synapomorphies such as a deep groove on the 
medial surface distal to the iliofibularis tubercle on 
the fibula, and a teardrop shaped articular surface for 
metatarsal III on the medial surface of the distal 
portion of metatarsal IV. The specimen is similar to 
Daspletosaurus torosus in the presence of a slender ridge 
along the posterior surface of metatarsal IV proximal to 
the distal metatarsal III attachment site, in contrast to 
the fat or concave condition in Tyrannosaurus rex. This 
represents the first unambiguous evidence of a 
tyrannosaurid dinosaur from the Mesa Verde Group, and 
represents an important biogeographic record situated 
between southerly coeval strata in the Kaiparowits 
(southern Utah) and San Juan (New Mexico) basins, and 
equivalent strata in Montana and Alberta.

A NEW JUVENILE TYRANNOSAURUS AND A REASSESSMENT OF 
ONTOGENETIC AND PHYLOGENETIC CHANGES IN TYRANNOSAUROID 
FORELIMB PROPORTIONS
WILLIAMS, Scott, Burpee Museum of Natural History, 
Rockford, IL, USA; BRUSATTE, 
Stephen , American Museum of Natural History, New York, 
NY, USA; MATHEWS, 
Joshua, Augustana College, Rock Island, IL, USA; CURRIE, 
Philip , University of Alberta, 
Edmonton, AB, Canada 
Tyrannosaurid theropods, including Tyrannosaurus and its 
closest relatives, are characterized by abnormally 
atrophied forelimbs. Little is known, however, about the 
evolution of this unusual feature, or whether small 
forelimbs were present throughout ontogeny or only in 
large-bodied adults. A new specimen of a juvenile 
Tyrannosaurus from the latest Maastrichtian Hell Creek 
Formation of Carter County, Montana helps address these 
questions. The partial associated skeleton is comprised 
of dorsal vertebrae, ribs, gastralia, front limb 
(scapulocoracoid, humerus, ulna, manual unguals) and 
hindlimb bones (femur, tibia, fibula, pedal ungual). 
Derived characters support referral to Tyrannosauridae 
(most likely Tyrannosaurus) and histological examination 
indicates that the specimen was a juvenile when it died. 
Most notably, several features of the forelimb show 
marked differences with adult tyrannosaurids. The humerus 
is longer in relation to the femur and more gracile when 
compared to adults, and has a slender, blade-like 
deltopectoral crest. The manual unguals, which include 
the first relatively complete second ungual described for 
Tyrannosaurus, are enormous. The large humerus and 
unguals indicate that the entire forelimb was relatively 
longer than in adults, demonstrating that forelimb 
proportions exhibited negative allometry during ontogeny. 
Juveniles, therefore, had larger forelimbs than adults, 
and the ontogenetic development of atrophied forelimbs 
occurred in concert with the development of the large, 
deep, and robust adult skull optimized for strong bite 
forces. This indicates a behavioral and dietary shift 
during ontogeny, which has not previously been documented 
in Tyrannosaurus. A similar trend of forelimb reduction 
is also seen in tyrannosauroid phylogeny. Small-bodied 
and gracile basal tyrannosauroids, such as Guanlong and 
Dilong, possess large arms and hands. Forelimb material 
is poorly known for most tyrannosauroids intermediate 
between basal forms and derived tyrannosaurids, but one 
such taxon, Dryptosaurus, has a small humerus but 
enormous hands, indicating that the proximal limb was 
reduced first in tyrannosauroid evolution.

AN ORNITHOMIMID-LIKE BASAL COELUROSAUR FROM THE EARLY 
CRETACEOUS (APTIAN) CEDAR MOUNTAIN FORMATION OF UTAH
SCHEETZ, Ashley, Brigham Young University, Provo, UT, 
USA; BRITT, Brooks, Brigham 
Young University, Provo, UT, USA; SCHEETZ, Rodney, 
Brigham Young University, Provo, 
UT, USA; RAUHUT, Oliver, Bayerische Staatssammlung für 
Paläontologie und Geologie, 
Munich, Germany; CHURE, Daniel, Dinosaur National 
Monument, Jensen, UT, USA 
A horizon near the base of the Yellow Cat Member of the 
Cedar Mountain Formation of east
ern Utah is yielding a number of fossils including fish, 
hybodontid shark coprolites, turtles, sphenodontids, 
ornithopods, ankylosaurs, and a theropod consisting of 
partial associated skeleton of a single individual with 
an estimated length of < 4m. The few recovered cranial 
bones of the theropod are indicative of a lightly built 
skull. The frontal suggests a large orbit, the occipital 
condyle is diminutive (12 mm diameter), and the dentary 
is delicate with supernumerary, minute alveoli ~2.5 mm 
long anteroposteriorly. No tooth crowns are preserved in 
the dentary but a 4 mm tall crown associated with the 
skull has a bulbous base. Cervicals are highly pneumatic 
with camellate internal structure, slightly amphicoeleous 
centra, and anteroposteriorly elongate, low neural 
spines. The three known cervicals are elongate, with 
centra up to 2.3 times as long as high, and cervical ?3 
is small in diameter, suggesting a long, tapering neck. 
No dorsals or sacrals are known. Proximal caudals bear 
thin spines and strongly backswept transverse processes. 
Distal caudals have prezygapophyses nearly 50% of centrum 
length, centra wider than tall, and skid-like chevrons. 
All caudals have a robust ventrolateral prezygapophysial 
ridge. The scapular blade is broad and the humerus is 
relatively straight, moderately built, and 33% longer 
than the lightly built radius.The ilium has a large 
acetabular shelf, the tibia & fibula are long and 
gracile, and distally the fibula articulates with the 
calcanium and a shelf on the astragalus. The astragalar 
ascending process is moderately high, straight-sided, and 
narrower than the astragalus body. The metatarsus is not 
arctometatarsalian but is long (metatarsal III 60% of 
tibial length). A preliminary cladistic analysis suggests 
the taxon is a basal coelurosaur and the elongate neck 
and greatly reduced dentition housed in a light skull are 
convergent with ornithomimids.

DESCRIPTION OF THE FIRST ORNITHOMIMID (DINOSAURIA) 
BONEBED FROM NORTH AMERICA WITH IMPLICATIONS FOR THE 
DISCRIMINATION, ONTOGENY AND BEHAVIOR OF ORNITHOMIMIDS
CULLEN, Thomas, Carleton University, Ottawa, ON, Canada; 
RYAN, Michael, Cleveland 
Museum of Natural History, Cleveland, OH, USA; SCHRÖDER-
ADAMS, Claudia, 
Carleton University, Ottawa, ON, Canada; KOBAYASHI, 
Yoshitsugu, Hokkaido University, 
Hokkaido, Japan; CURRIE, Philip, University of Alberta, 
Edmonton, AB, Canada 
Bonebeds can provide important anatomical, taphonomic, 
and ontogenetic information about relatively poorly known 
taxa, and provide evidence for behavioral inferences. 
Such accumulations of large vertebrates are well-
documented in the Late Cretaceous fossil record, but 
theropod bonebeds are rare, with less than 10 being known 
worldwide. Three partial postcrania from the Upper 
Cretaceous Horseshoe Canyon Formation of Alberta, Canada, 
represent the first known bonebed of ornithomimids in 
North America, and only the third documented ornithomimid 
bonebed in the world, the others being found in China. 
The specimens were collected in 1926 from a partially 
eroded locality that may have once been larger and 
contained more individuals; it is now believed to have 
been completely eroded away. The three individuals 
recovered are in varying stages of completeness, with 
little material preserved anterior to the pelvic girdle 
(probably lost through erosion). All three specimens are 
morphologically similar, with one being 7% larger and 
close to the size of the largest ornithomimids recovered 
from the formation. Although no cranial or manual 
elements were preserved, the material probably represents 
either Struthiomimus or Ornithomimus; both genera have 
been recovered from the formation as skeletons with 
skulls, and individual elements, especially numerous 
pedal phalanges. The pes of two individuals are well 
preserved. Selected pedal elements from these and other 
ornithomimid taxa were used in a limited principle 
component analysis, but were not found to vary 
significantly between taxa, confrming that pedal 
phalanges have limited taxonomic utility for this group. 
Histological analyses from the fibulae of the largest and 
one of the smaller specimens gave putative ages of 4 and 
3 years, respectively. This suggests that, similar to the 
Chinese bonebeds, this site preserves subadult-sized 
specimens, and that other large ornithomimid specimens 
from the formation may not be fully grown or mature. 
Sedimentological and taphonomic evidence from the 
locality suggests that the bonebed represents the first 
record of gregarious behavior in ornithomimids in North 
America.

A NEARLY COMPLETE SKELETON OF A NEW ORNITHOMIMID FROM THE 
NEMEGT FORMATION OF MONGOLIA
KOBAYASHI, Yoshitsugu, Hokkaido University Museum, 
Hokkaido University, Sapporo, 
Hokkaido, Japan; LEE, Yuong-Nam, Korea Institute 
Geoscience and Mineral Resources, 
Daejeon, Korea, South; LÜ, Junchang, Institute of 
Geology, Chinese Academy of Geological 
Sciences, Beijing, China; RYAN, Michael, Cleveland Museum 
of Natural History, 
Cleveland, OH, USA; CURRIE, Philip, University of 
Alberta, Edmonton, AB, Canada 
The remains of the Mongolian ornithomimids, Gallimimus 
bullatus and Anserimimus planinychus are common 
occurrences in the Upper Cretaceous Nemegt Formation. In 
2006, the Korea-Mongolia International Dinosaur 
Expedition recovered a beautifully-preserved, uncrushed 
ornithomimid skeleton from Ulan Khushuu in the Gobi 
Desert, Mongolia. The almost complete skeleton has a 
disarticulated skull, but missing only the tail, and, is 
referable to a new taxon. The Ulan Khushuu specimen 
differs from all other ornithomimids in having an 
additional ridge along the deltopectral crest, nearly 
straight manual ungual phalanges, and an accessory 
ventral process on the lateral posterior condyle of the 
proximal tibia. It shows an affinity with the other two 
Nemegt ornithomimids in having a laterally displaced 
glenoid of the coracoid. Although it shares several 
derived characters present in the Qiupa ornithomimid from 
China and in North American taxa, such as the anterior 
extension of the pubic boot and large acute angle between 
the dorsal edge of the pubic boot and shaft, it is basal 
to all North American taxa due to its lack of the ventral 
expansion of the pubic boot. Cranial material, especially 
the braincase, is three-dimensionally preserved, and 
reveals important anatomical information. Similar to 
Shenzhousarus orientalis and Sinornithomimus dongi from 
China, the skeleton preserves a mass of gastroliths 
within articulated ribs and gastralia, the first such 
occurrence in a Mongolian ornithomimid. The possession of 
gastroliths has been suggested as evidence for herbivory 
in this group, but the presence of isolated fish 
vertebrae in the matrix of the gastrolith mass may 
represent in situ stomach contents. This would suggest 
that the new ornithomimid may have had a more omnivorous 
diet.



A NEW BASAL THERIZINOSAUROID FROM THE LOWER CRETACEOUS 
YIXIAN FORMATION OF LIAONING, CHINA
LÜ, Junchang, Institute of Geology, Chinese Academy of 
Geological Sciences, Beijing, 
China; KOBAYASHI, Yoshitsugu, Hokkaido University, 
Sapporo, Hokkaido, Japan; XU, Li, 
Henan Geological Museum, Zhengzhou, China; PU, Hanyong, 
Henan Geological Museum, 
Zhengzhou, China; WU, Yanhua, Henan Geological Museum, 
Zhengzhou, China 
Therizinosauroids are an unusual group of theropod 
dinosaurs, found mostly in the Cretaceous deposits in 
Mongolia, China and western USA.  The basal forms of this 
group are represented by fragmentary or disarticulated 
material. Here, we report a nearly complete, articulated 
skeleton of a new basal therizinosauroid from the Early 
Cretaceous Yixian Formation of Jianchang County, western 
part of Liaoning Province, which sheds light on 
understanding of anatomy of basal therizinosauroids. The 
new dinosaur shows some therizinosauroid features (e.g., 
dentary shelf, tooth morphology, edentulous premaxilla, 
down-turned symphyseal region, and large nares) and is 
characterized by 27 closely packed maxillary teeth, a 
large maxillary fenestra (separated from the antorbital 
fenestra by a vertical interfenestral bar similar to some 
troodontids), and short mandibular symphyses. This taxon 
bears many primitive characters, which are not seen in 
other therizinosauroids: closely packed maxillary teeth, 
consistent size of dentary teeth, weakly expanded 
proximal and distal ends of humerus, low ilium with 
horizontal dorsal edge, and the propubic condition with a 
shallow pubic boot. The combination of these 
plesiomorphic characters suggests that this taxon is 
placed as a basal therizinosauroid.


ALSO:

Thibaud Souter, Raphael Cornette, Julio Pedraza, John 
Hutchinson and Michel Baylac (2010)
Two applications of 3D semi-landmark morphometrics 
implying different template designs: the theropod pelvis 
and the shrew skull.
Comptes Rendu Palevol (advance online publication) 
doi:10.1016/j.crpv.2010.09.002 

Geometric morphometrics involves defining landmark points 
to generate a discrete representation of an object. This 
crucial step is strongly influenced by the biological 
question guiding the analysis, and even more when using 
curve and surface semi-landmarks methods, because these 
require to generate a template of reference. We exemplify 
these constraints using two datasets from projects with 
very different backgrounds. The Theropod Dataset is a 
functional morphometric analysis of different extinct and 
extant theropod pelves. The Shrew Dataset is a 
populational morphometric analysis of the white-toothed 
shrew with very small variations in skull shape. We 
propose a novel procedure to generate a regular template 
configuration, using polygonal modelling tools. This 
method allows us to control the template geometry and 
adapt its complexity to the morphological variation in 
the sample. More studies are necessary to assess the 
morphometric and statistical importance of template 
design in curve and surface analyses.
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