Carnivorous gastroliths (was RE: Giant carnivorous geese)

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

>  >>>
> Sorry Mike - I was contributing to the debate over diet in giant 'geese'
> (dromornithids). The presence of gastroliths has been forwarded as an
> argument against a carnivorous habit for these birds. In response I
> point out that this is anything but a watertight argument given the
> presence of gastroliths in some carnivorous dinosaurs.
> <<<
>       Have they found any in unambiguous carnivores? I know they're seen
> in coelurosaurs like ornithomimids and Caudipteryx, but both of these
> guys look like herbivores to me- ornithomimids being really similar to
> ostriches, rheas and emus in a lot of respects, not to mention far and
> away more abundant than any of the other, unquestionably carnivorous
> theropods, and Caudipteryx is a relative of Oviraptorosauria which
> themselves are pretty likely to turn out to be herbivores or omnivores
> for a number of different reasons (for one thing, they are pretty
> abundant compared to other theropods in Mongolia).
>
Gastroliths are present in Baryonyx, in Lourinhanosaurus (for which the
skull is unknown, granted, so is arguably not an unambiguous carnivore!),
and in Poekilopleuron (again, ditto).

                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
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