Re: Brachiosaur chewing

[Tom Holtz <tholtz@geochange.er.usgs.gov>]

>I read or heard somewhere that the Brachiosaur in JP was chewing wrong.
> Anyone care to comment on that?  Is it true?  Mikiel and I were wondering.

Reptilian jaw mechanics (with a few very significant exceptions) prohibit
side to side motion - i.e., chewing.  If you watch iguanas or turtles eat,
for example, you see that they slice or mush the food with the sides of
their jaws, then lick the pulp up.

The exceptions to this prohibition are the ornithopod dinosaurs, and in
particular the hadrosaurids.  As Ostrom, Weishample, Norman, and other
ornithopod specialists have pointed out, there is a great degree of
mobility in the jaws of duck-bills.  Combined with their massive grinding
surfaces, hadrosaurids were probably remarkable chewers.

On the other hand, sauropods like Brachiosaurus had a more typical
reptilian jaw arrangement.  They could bite, but not much else.

                                
Thomas R. Holtz, Jr.                                   
tholtz@geochange.er.usgs.gov
Vertebrate Paleontologist in Exile                  Phone:      703-648-5280
U.S. Geological Survey                                FAX:      703-648-5420
Branch of Paleontology & Stratigraphy
MS 970 National Center
Reston, VA  22092
U.S.A.