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RE: JP3-Spinosaurus

> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Gavin Rymill
> In one of my Spinosaurus reconstructions I had shown three
> manugal digits of
> similar length all with normal-sized claws, as has been depicted
> in Jurassic
> Park III.
> http://gavinrymill.com/newart/spinosaurus.jpg
> I have subsequently been critisised for this. I was told that the large
> thumb claw is "missing".
> Can anyone tell me if there is any evidence for this large claw? My
> understanding was that Spinosaurus is known from fragmentary dentary,
> vertebrae, hindlimb elements, teeth [destroyed] and neck vertebra,
> fragmentary dentaries, dorsal neural arch.
> No mention of any parts of the forelimbs.
> Is the large thumb claw an inference made by people comparing the
> animal to
> Baronyx?
Large thumb claws are known for those spinosaurids for which manual material
has been assigned (Baryonyx and Suchomimus).  Furthermore, probable
spinosaurid outgroups (Torvosaurus, for example) seem to possess an enlarged
thumb claw.  It is thus inferred that large thumb claws are primitive for
Spinosauridae as a whole, and thus lacking positive evidence to the contrary
that Spinosaurus itself had a large thumb claw.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
                College Park, MD  20742
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796

> -----Original Message-----
> Gav
> www.gavinrymill.com        ICQ: 33916140  /  AOLIM: ExtinctGav