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Dingo vs. Thylacine Jaw Mechanics: Implications for Theropods?



Congratuations to DMLer Colin McHenry:
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Proc Biol Sci. 2007 Sep 4; [Epub ahead of print] 
Computer simulation of feeding behaviour in the
thylacine and dingo as a novel test for convergence
and niche overlap.Wroe S, Clausen P, McHenry C, Moreno
K, Cunningham E.
School of Biological Earth and Environmental Sciences,
University of New South Wales, Sydney, New South Wales
2052, Australia.

The extinct marsupial thylacine (Thylacinus
cynocephalus) and placental grey wolf (Canis lupus)
are commonly presented as an iconic example of
convergence. However, various analyses suggest
distinctly different behaviours and specialization
towards either relatively small or large prey in the
thylacine, bringing the degree of apparent convergence
into question. Here we apply a powerful engineering
tool, three-dimensional finite element analysis
incorporating multiple material properties for bone,
to examine mechanical similarity and niche overlap in
the thylacine and the wolf subspecies implicated in
its extinction from mainland Australia, Canis lupus
dingo. Comparisons of stress distributions not only
reveal considerable similarity, but also informative
differences. The thylacine's mandible performs
relatively poorly where only the actions of the jaw
muscles are considered, although this must be
considered in the light of relatively high bite
forces. Stresses are high in the posterior of the
thylacine's cranium under loads that simulate
struggling prey. We conclude that relative prey size
may have been comparable where both species acted as
solitary predators, but that the dingo is better
adapted to withstand the high extrinsic loads likely
to accompany social hunting of relatively large prey.
It is probable that there was considerable ecological
overlap. As a large mammalian hypercarnivore adapted
to taking small-medium sized prey, the thylacine may
have been particularly vulnerable to disturbance.
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The article cites several references to predatory
dinosaurs.  It would be really interesting to run a
similar analysis for several genera within a single
rock unit (Morrison, Hell Creek/Lance) to see how much
mechanical overlap in theropods existed, and the
potential ecological implications. For example,
comparing *Allosaurus* and *Ceratosaurus*, or
*Gorgosaurus* and *Daspletosaurus*...

Guy Leahy