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Triassic dino tracks in this week's Science



Greetings,

Two short items (a comment and a response to comment) on dinosaurs in the
latest issue of Science:

Thulborn, T. 2003. Comment on "Ascent of Dinosaurs Linked to an Iridium
Anomaly at the Triassic-Jurassic Boundary." Science 301: 169.

A comment on Olsen et al.'s paper last year, suggesting that a) an impactor
is the cause of the Tr-J extinction and b) such extinction allowed the rise
of giant theropods, among others.  Thulborn discusses trackways and prints
from Molteno Formation of southern Africa and the contemporaneous Ipswich
Coal Measures of southeastern Queensland, Australia (both Carnian).  These
prints are big: one is 43 cm long, and thus Allosaurus-sized.  He suggests
that large theropods may have been common in southern Pangaea (Gondwana) and
only migrated to Lauriasian  Pangaea in the Jurassic.

Olsen, P. E., H.-D. Sues, E. C. Rainforth, D. V. Kent, C. Koeberl, H. Huber,
A. Montanari, S. J. Fowell, M. J. Szajna, and B. W. Hartline. 2003. Response
to Comment on "Ascent of Dinosaurs Linked to an Iridium Anomaly at the
Triassic-Jurassic Boundary." Science 301: 169.

In response, Olsen et al. point to features of the Aussie tracks with those
of big pentadactyl tracks from the Carnian of North Carolina
(Parachirotherium, which may be from pseudosuchians).  The latter can be
misinterpreted as theropod tracks if digits I and V are poorly preserved.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
http://www.geol.umd.edu/~tholtz/tholtz.htm
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796