Re: Dino nasal passages

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 11:36 PM 10/16/98 EDT, Greg Paul wrote:
>Anyway, got to take a look at two superbly 3-D
>preserved allosaurus snouts, including one with the internal view fully
>preserved intact.

I've seen some excellent X-rays of some of these (or perhaps other?)
specimens.  Quite nice.

>These show that the avetheropod nasal passage was long and
>fairly complex. (Also, I do not think tyrannosaurs had a true "secondary
>palate".)

A curious statement, since tyrannosaurids clearly have an extension of the
premax and maxilla which contact the vomer along the midlength, hence a
solid roof to the mouth, hence a "secondary palate".  The way they acheive
this anatomically is different from the way crocs or mammals do it, but it
is still a solid roof to the mouth.  It is true that advanced
tyrannosaurines (_Tyrannosaurus_ in particular) has the most extensive
development, and that in more primitive forms it is best developed in the
front end of the snout.  Nevertheless, most non-coelurosaurian theropods do
not show even this development.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661