Re: Rex Jaws

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

At 10:59 PM 6/2/99 GMT, Jessica W wrote:
>I was wondering how T.rex jaws went..
>I mean, did the teeth overlap when the jaws were closed? Or did they line up 
>like human teeth do, with the one row resting ontop of the other? Skulls at 
>museums, and drawings in various books don't seem to help me much, but it 
>seems that the teeth line up row-on-row, kinda like people teeth in most 
>skulls on display..
>is this how they'd be in life?--seems kinda wierd to me.

_T. rex_ (and most toothed theropods, for that matter) had a "wrap-around
overbite": the whole upper surface of the lower jaw fits within the inside
of the lower jaw.  If you look from below at a skull with the jaw closed,
the lower jaw fits inside the upper part of the mouth, and you can see all
the teeth in the upper jaw.

This is very, very different from the condition in humans (where are teeth
contact directly with each other), and also very different from typical
kid's books illustrations and many toys and models (where the teeth are
shown as matching "sawblades", one row fitting directly into the spaces in
the other).

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