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Dinosaur papers in the latest Nature



These just in:

Emily Rayfield's work on the bite forces of Allosaurus (presented at the
Romer Prize talks last year) is now out:

Rayfield, E.J., D.B. Norman, C.C. Horner, J.R. Horner, P.M. Smith, J.J.
Thomason & P. Upchurch.  2001.  Cranial design and function in a large
theropod dinosaur.  Nature 409: 1033-1037.
Rayfield et al. used the industrial design technique of finite element
analysis (FEA) to reconstruct the loading forces and stresses and so forth
in the skull of Big Al (MOR 693), one of the most complete _Allosaurus
fragilis_ specimens known.  They tried a variety of different types of bites
using this system, and found in general lower bite forces than in _T. rex_,
_Alligator_, and lions (and comparable to wolves and leopards).  However,
the skull itself is "overbuilt" (capable of surviving considerably higher
stresses than can be generated by biting).  They suggest that Big Al
employed a high impact bite of great speed rather than a prolonged grapple
(as might be found in the crushing bite of tyrant dinos).

This article has an accompanying News & Views by Greg Erickson:
Erickson, G.M. 2001. The bite of _Allosaurus_. Nature 409: 987-988.

P.S. This paper falls into the category of "I wanted to do this analysis,
but they did a better job than I could."  When I saw a talk on using FEA on
basal therapsid skulls by Rayfield's classmate Ian Jenkins some years ago, I
thought that this would be a great technique by which to evaluate theropod
feeding strategies.  If they (or others) refine this approach and start
looking at other taxa, we might be able to quantify those various ideas I've
been proposing about alternative predatory habits in large theropods.

Also in this week's Nature:
Sanz, J.L., L.M. Chiappe, Y. Fernadez-Jalvo, F. Ortega, B. Sanchez-Chillon,
F.J. Poyato-Ariza & B.P. Perez-Moreno.  2001.  An Early Cretaceous pellet.
Nature 409: 998-999.

They describe an association of four juvenile birds in the Las Hoyas
locality.  The birds differ in size and anatomical detail, and appear to
represent three different taxa (not yet named, or at least not yet
confidently assignable to the currently named Las Hoyas birds).

The weird thing: they are very close to each other, feathers are still
present, but their bones have the pitted characteristic of partially
digested material.  This suggests to the authors that these represent an
example of three species nest parasitism (unlikely) or a reguritated pellet.
If so, what ate the birds and ralphed them up?  They suggest small theropods
or large pterosaurs as the most likely culprits.

Cool stuff.

                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