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RE: The (brain)case is closed? (Re: Burpee Conference)



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Phil Bigelow
>
> Tom, Ken,
> So, no chance that this is ontogenetic?

There is absolutely every chance it is ontogenetic! However, it might not be. 
Further tests to be done.

> Do any extant reptiles remodel the inside of their braincase as they age?

Remains to be studied. As has the question of what changes lambeosaurine, 
centrosaurine, or protoceratopsid skulls go through
(logical comparisons due to good growth series record and huge size changes, at 
least for first two).

> What does the inside of the Burpee head look like, compared to the
> holotype?

Unknown: they haven't been found.

> Is there a wide variation in morphology on the inside of the braincases
> of adult T. rexes?

Sample size of 3 shows not too much variation.

> I presume that the hypothesis is that as baby T. rexes age, their sensory
> apparati would change, because their prey/hunting regime changes as they
> get bigger.  Optic lobes would shrink (proportionally, not literally) or
> enlarge and olfactory lobes do the same (possibly in reverse compared to
> the optic lobes).  The brain stem may have been proportionally bigger in
> T. rex babies, perhaps because of activity/coordination differences
> between the young and the adults.

Very reasonable hypotheses.

> CAT scans of soft tissue (brains) show that morphology differences are
> quite significant between baby and adult mammals, particularly in the
> highly altricial ones like primates.

Very true.

Please, folks, this was just the INITIAL presentation of the data. There is 
literally years of work remaining to be done!

(But you do make some good points.)

So, in short, the case is by no means closed.

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
        Mailing Address:
                Building 237, Room 1117
                College Park, MD  20742

http://www.geol.umd.edu/~tholtz/
http://www.geol.umd.edu/~jmerck/eltsite
Phone:  301-405-4084    Email:  tholtz@geol.umd.edu
Fax (Geol):  301-314-9661       Fax (CPS-ELT): 301-405-0796