Sinornithomimus, new dino in Acta Palaeontologica Polonica

[bh480@scn.org]

From: Ben Creisler bh480@scn.org
Sinornithomimus, new dino in Acta Palaeontologica Polonica

The new issue of Palaeontologica Polonica has a number of 
dinosaur articles. The pdfs worked when I tried them.
http://app.pan.pl/

Hurum, Jørn H. and Karol Sabath, 2003. Giant theropod 
dinosaurs from Asia and North America: Skulls of 
Tarbosaurus bataar and Tyrannosaurus rex compared. Acta 
Palaeontologica Polonica 48 (2), 2003: 161-190.
The skull of a newly prepared Tarbosaurus bataar is 
described bone by bone and compared with a disarticulated 
skull of Tyrannosaurus rex. Both Tarbosaurus bataar and 
Tyrannosaurus rex skulls are deep in lateral view. In 
dorsal view, the skull of T. rex is extremely broad 
posteriorly but narrows towards the snout; in Ta. bataar 
the skull is narrower (especially in its ventral part: the 
premaxilla, maxilla, jugal, and the quadrate complex), and 
the expansion of the posterior half of the skull is less 
abrupt. The slender snout of Ta. bataar is reminiscent of 
more primitive North American tyrannosaurids. The most 
obvious difference between T. rex and Ta. bataar is the 
doming of the nasal in Ta. bataar which is high between 
the lacrimals and is less attached to the other bones of 
the skull, than in most tyrannosaurids. This is because of 
a shift in the handling of the crushing bite in Ta. 
bataar. We propose a paleogeographically based division of 
the Tyrannosaurinae into the Asiatic forms (Tarbosaurus 
and possibly Alioramus) and North American forms 
(Daspletosaurus and Tyrannosaurus). The division is 
supported by differences in anatomy of the two groups: in 
Asiatic forms the nasal is excluded from the major series 
of bones participating in deflecting the impact in the 
upper jaw and the dentary-angular interlocking makes a 
more rigid lower jaw. 

Currie, Philip J., 2003. Cranial anatomy of tyrannosaurid 
dinosaurs from the Late Cretaceous of Alberta, Canada. 
Acta Palaeontologica Polonica 48 (2), 2003: 191-226.
Beautifully preserved, nearly complete theropod skeletons 
from Alberta (Canada) allow re-evaluation of the taxonomic 
status of North American tyrannosaurids. It is concluded 
that the most parsimonious interpretation of relationships 
leads to the separation of the two species of 
Albertosaurus (sensu Russell 1970) into Gorgosaurus 
libratus from the Campanian Dinosaur Park Formation and 
Albertosaurus sarcophagus from the upper Campanian/lower 
Maastrichtian Horseshoe Canyon Formation. Albertosaurus 
and Gorgosaurus are closely related, but can be 
distinguished from each other by more characters than are 
known to justify generic distinction within another 
tyrannosaurid clade that includes Daspletosaurus, 
Tarbosaurus and Tyrannosaurus. Daspletosaurus is known 
from multiple species that cover extensive geographic, 
ecological and temporal ranges, and it is sensible to 
maintain its generic distinction from Tyrannosaurus. All 
tyrannosaurid species have consistent ontogenetic trends. 
However, one needs to be cautious in assessing ontogenetic 
stage because many characters are size-dependent rather 
than age-dependent. There are relatively few osteological 
differences that can distinguish tyrannosaurid species at 
any age. For example, Nanotyrannus lancensis is probably a 
distinct species from Tyrannosaurus rex because there is 
no evidence of ontogenetic reduction of tooth counts in 
any other tyrannosaurid species. Some characters that are 
good for separating mature tyrannosaurids, such as 
differences in the sizes and shapes of maxillary 
fenestrae, are not useful for identifying the species of 
juveniles. 

Currie, Philip J. , Jørn H. Hurum, and Karol Sabath, 2003. 
Skull structure and evolution in tyrannosaurid dinosaurs. 
Acta Palaeontologica Polonica 48 (2), 2003: 227-234.
Tyrannosauridae can be subdivided into two distinct 
subfamilies-the Albertosaurinae and the Tyrannosaurinae. 
Previously recognized subdivisions Aublysodontinae and 
Shanshanosaurinae are rejected because they are based on 
insufficient material and juvenile specimens. Our results 
are based upon a phylogenetic analysis using PAUP program 
(Swofford 1999) of 77 skull characters and seven genera 
(Albertosaurus, Alioramus, Daspletosaurus, Gorgosaurus, 
Nanotyrannus, Tarbosaurus, and Tyrannosaurus); with 
Allosaurus as outgroup. Of the 77 characters used, more 
than half were parsimony informative. A single most 
parsimonious tree was obtained with the Tree Length being 
88. The analysis of cranial characters and comparison of 
postcranial features reveal that Tarbosaurus bataar is not 
the sister taxon of Tyrannosaurus rex (contra Holtz 2001). 
Their similarities are partially due to the fact that both 
are extremely large animals. Thus, Tarbosaurus should be 
considered a genus distinct from Tyrannosaurus.

Kobayashi Yoshitsugu and Jun-Chang Lü, 2003. A new 
ornithomimid dinosaur with gregarious habits from the Late 
Cretaceous of China. Acta Palaeontologica Polonica 48 (2), 
2003: 235-259.
At least fourteen ornithomimid skeletons were recovered 
from the Upper Cretaceous Ulansuhai Formation in Nei 
Mongol (Inner Mongolia) Autonomous Region of China. They 
are assigned to a new genus and species, Sinornithomimus 
dongi. The anatomy of the species is described. 
Comparative and phylogenetic studies of ornithomimosaurs 
prove that these skeletons represent a new taxon that is 
more derived than Archaeornithomimus and more basal than 
the clade of [(Anserimimus + Gallimimus) + [Struthiomimus 
+ (Dromiceiomimus + Ornithomimus)]]. The phylogenetic 
analysis suggests that the structure of the hand is 
similar to Archaeornithomimus and represents an 
intermediate condition between the primitive (Harpymimus) 
and the derived (Anserimimus, Gallimimus, Struthiomimus, 
Dromiceiomimus, and Ornithomimus) conditions. The 
monophyly of Ornithomimidae is supported by a single 
synapomorphy (arctometatarsalian condition) in this 
analysis, indicating that the family is not as strongly 
supported as previously suggested. The analysis also 
implies that the shape of the rhamphotheca in North 
American taxa may have been different from that in Asian 
taxa. Previous study suggests herbivorous habits of this 
dinosaur based on characteristics of the gastroliths. The 
skeletons of Sinornithomimus were collected from a single 
monospecific bonebed with a high ratio of juvenile 
individuals (11 of the 14), suggesting gregarious behavior 
for protection from predators. The abundance of juveniles 
indicates high mortality of juveniles or a catastrophic 
mass mortality of a population with a high proportion of 
juveniles. An increase in the relative ratio of the tibia 
to femur through the ontogeny of Sinornithomimus suggests 
higher cursoriality in adult individuals than in 
juveniles. 

You, Hai-Lu & Peter Dodson, 2003. Redescription of 
neoceratopsian dinosaur Archaeoceratops and early 
evolution of Neoceratopsia. Acta Palaeontologica Polonica 
48 (2), 2003: 261-272.
Archaeoceratops oshimai Dong and Azuma, 1997 is a basal 
neoceratopsian from the late Early Cretaceous of 
Mazongshan area, Gansu Province, northwest China. Here we 
provide a detailed description on Archaeoceratops oshimai 
based on both the holotype, which consists of a well 
preserved, nearly complete skull, partial vertebral 
column, and partial pelvis, and the paratype, which 
consists of a partial vertebral column including a nearly 
complete tail, a partial pelvis, fragmentary hind limb 
bones, and a complete pes. Cladistic analysis shows that 
Archaeoceratops is the sister group to all currently known 
Late Cretaceous Neoceratopsia, and Late Cretaceous 
Neoceratopsia diverged into two clades: the Asian 
Protoceratopsidae and the North American Ceratopsoidea, 
indicating a dual evolution for the two major groups of 
horned dinosaurs in two landmasses of Late Cretaceous. A 
suite of derived features characterizes Ceratopsoidea, 
such as a round-shaped external naris, a long caudolateral 
process of the rostral bone, and ventrally curved 
premaxillary ventral edge.