New Paper: Rayfield adds Coelophysis to the FEA mix

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

Just out:

Rayfield, E.J. 2005. Aspects of comparative cranial mechanics in the theropod 
dinosaurs Coelophysis, Allosaurus and Tyrannosaurus.
Zool. J. Linnean Soc. 144:309-316.

ABSTRACT
The engineering analysis technique finite element analysis (FEA) is used here 
to investigate cranial stress and strain during biting
and feeding in three phylogenetically disparate theropod taxa: Coelophysis 
bauri, Allosaurus fragilis and Tyrannosaurus rex. Stress
patterns are generally similar in all taxa with the ventral region of the skull 
tensed whilst the dorsal aspect is compressed,
although the skull is not purely behaving as a cantilever beam as there is no 
discernible neutral region of bending. Despite
similarities, stress patterns are not wholly comparable: there are key 
differences in how certain regions of the skull contain
stress, and it is possible to link such differences to cranial morphology. In 
particular, nasal morphology can be explained by the
stress patterns revealed here. Tyrannosaurus models shear and compress mainly 
in the nasal region, in keeping with the
indistinguishably fused and expanded morphology of the nasal bones. Conversely 
Allosaurus and Coelophysis models experience peak
shear and compression in the fronto-parietal region (which is tightly 
interdigitated and thickened in the case of Allosaurus) yet in
contrast the nasal region is lightly stressed, corresponding to relatively 
gracile nasals and a frequently patent internasal suture
evident in Allosaurus. Such differences represent alternate mechanical 
specializations between taxa that may be controlled by
functional, phylogenetic or mechanical constraints. Creation of finite element 
models placed in a phylogenetic context permits the
investigation of the role of such mechanical character complexes in the cranium 
of nonavian theropods and the lineage leading
towards modern birds.  © 2005 The Linnean Society of London, Zoological Journal 
of the Linnean Society, 2005, 144, 309316.


                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
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