[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Uchuu Senkan New Papers



Norell, M.A., P.J. Makovicky, G.S. Bever, A.M. Balanoff, J.M. Clark, R.
Barsbold, & T. Rowe. 2009. A Review of the Mongolian Cretaceous Dinosaur
Saurornithoides (Troodontidae: Theropoda). American Museum Novitates 3654:
1-63.

Abstract

We review the morphology, taxonomy, and phylogenetic relationships of the
upper Cretaceous Mongolian troodontid Saurornithoides. Saurornithoides
mongoliensis is known only by the holotype from Bayan Zag, Djadokhta
Formation. This specimen includes a nearly complete, but weathered, skull
and mandibles, a series of dorsal, sacral, and caudal vertebrae, and a
partial pelvic girdle and hind limb. Saurornithoides junior, here referred
to Zanabazar, also is known only by the holotype from Bugiin Tsav, Nemegt
Formation. This specimen consists of a skull and partial mandible, a series
of sacral and caudal vertebrae, a partial pelvic girdle, and the distal part
of the right hind limb. Saurornithoides + Zanabazar is one of the few
Mongolian taxa known from both the Djadokhta and Nemegt formations. The
monophyly of Saurornithoides + Zanabazar has not been seriously questioned
historically, yet empirical support for this clade is currently tenuous. A
privileged phylogenetic relationship between Saurornithoides, Zanabazar, and
the North American troodontid Troodon formosus is supported by numerous
characters including the presence of a subotic recess, lateroventrally
projecting and hollow basipterygoid processes, a lacrimal whose anterior
process is significantly longer than its posterior process, a highly
pneumatized parasphenoid rostrum, a constricted neck of the occipital
condyle, a symphyseal region of the dentary that is slightly recurved
medially, and an obturator process located near the middle of the ischiadic
shaft. CT data for the skulls of both species facilitated a description of
the endocranial anatomy of Saurornithoides mongoliensis and Zanabazar
junior, including a reconstruction of the endocranial space of Zanabazar
junior. Despite being the largest of the known troodontid species, the
endocranial volume of Zanabazar junior is considerably smaller than that
estimated for Troodon formosus, suggesting that the extremely high
encephalization quotient of Troodon formosus may be autapomorphic among
troodontids.

 Derivation of Name: In honor of Zanabazar (1635?1723), the first Bogd Gegen
of Mongolia.

------

A.M. Balanoff, X. Xu, Y. Kobayashi, Y. Matsufune, & M.A. Norell. 2009.
Cranial Osteology of the Theropod Dinosaur Incisivosaurus gauthieri
(Theropoda: Oviraptorosauria). American Museum Novitates 3651: 1-35.


Abstract

We provide a description of the holotype skull of the unusual oviraptorosaur
Incisivosaurus gauthieri. Previous phylogenetic analyses have placed this
taxon firmly within Oviraptorosauria near the base of the clade; however,
until now only a cursory description of this important specimen was
available. The presence of many primitive characteristics (e.g., maxillary
and dentary teeth as well as an extended palate and rostrum) indicates that
the observed similarities between avians and derived oviraptorids are
convergences rather than shared derived characters. In addition, we clarify
previous descriptions of several ambiguous anatomical features, most notably
of the palate. We also employ computed tomographic (CT) analysis, which
allows for a more complete description of the braincase and the
reconstruction of an endocranial endocast. CT imagery reveals features that
were before unobtainable, such as the presence of a replacement tooth behind
the large rodentiform incisor in the premaxilla. This arrangement indicates
that although the incisiform teeth of I. gauthieri are morphologically
distinct they are replaced in typical archosaurian fashion.

-----

A.H. Turner, S.J. Nesbitt, & M.A. Norell. 2009. A Large Alvarezsaurid from
the Late Cretaceous of Mongolia. American Museum Novitates 3648: 1-14.


Abstract

We report a new alvarezsaurid, Kol ghuva, from the Late Cretaceous of
Mongolia that demonstrates that the clade was not restricted to small taxa
(3?15 kg). The specimen was found at the Ukhaa Tolgod locality, which has
previously produced only a single diminutive alvarezsaurid, Shuvuuia
deserti. Although known only from a well-preserved right foot, the new taxon
is diagnosable by the following combination of characters: extensor grooves
on digit IV phalanges; robust flexor tubercle on pedal unguals; MT III does
not reach ankle; accessory dorsomedial flange absent on the medial side of
the distal end of the MT II; MT II shorter than MT IV; and MT III extends
higher proximally than other alvarezsaurids (more than ½ total metatarsus
length). The new taxon provides additional insight into the diversity of
this clade and the dinosaurian assemblage of Ukhaa Tolgod.

 Etymology

>From Mongolian köl, ?foot?
(http://www.linguamongolia.co.uk/cgi-bin/searchDb3.plsearch_paramfootcmdSubm
itSearchlangselectenglish) + ghuv-a, ?beautiful?
(http://www.linguamongolia.co.uk/cgi-bin/searchDb3.plsearch_parambeautifulcm
dSubmitSearchlangselectenglish).



Thomas R. Holtz, Jr.
Email: tholtz@umd.edu   Phone: 301-405-4084
Office: Centreville 1216                        
Senior Lecturer, Vertebrate Paleontology
Dept. of Geology, University of Maryland
http://www.geol.umd.edu/~tholtz/
Fax: 301-314-9661               

Faculty Director, Earth, Life & Time Program, College Park Scholars
http://www.geol.umd.edu/~jmerck/eltsite/
Faculty Director, Science & Global Change Program, College Park Scholars
http://www.geol.umd.edu/sgc
Fax: 301-314-9843

Mailing Address:        Thomas R. Holtz, Jr.
                        Department of Geology
                        Building 237, Room 1117
                        University of Maryland
                        College Park, MD 20742 USA