RE: Agonized death in dinos - my thoughts.

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

> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu]On Behalf Of
> Jura
> Sent: Friday, June 08, 2007 4:37 PM
> To: dinosaur@usc.edu
> Subject: Agonized death in dinos - my thoughts.

> Finally, the biggest problem I noted was that there
> was never a mention of the different body design of
> mammals and dinosaurs, compared to most reptiles.
> Mammals and dinosaurs are laterally compressed
> animals. When they die they fall to their sides. Most
> reptiles are dorsoventrally compressed. When they die,
> they die on their stomachs. Opisthotony is going to be
> selectively preserved in dinos and mammals, more often
> than other reptiles, simply for the fact that the
> hypercontracted muscles aren't fighting the constant
> tug of gravity. For that same reason, one would expect
> pleurothotonic positions to be more preservationally
> biased in squat reptiles like _Hyphalosaurus_.

Agreed. Indeed, dinosaurs and those mammals for which opsithotony are discussed 
are laterally compressed animals with a parasaggital
gait, while smaller mammals are less-so (and, as their work in the Jehol Group 
shows, such mammal(iform)s do not show this death
posture).

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
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/
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