Re: Don't leave the girls out (was FW: Dinosaur Exhibit)

["Timothy Williams" <twilliams_alpha@hotmail.com>]

Ralph W. Miller III wrote:

> Some dinosaur species seem to occur in two morphotypes within a
> population, but which is male and which is female?  Some scientists believe
> that the females were larger and more robust than the males, but we don't 
> know
> that for sure.

Where _T. rex_ is concerned, the robust morph has been reported as having a 
more robust maxilla and mandible, slightly more pronounced lacrimal horn, 
larger teeth, and more robust pelvis and vertebrae.

Robust: CMNH 9380 (type), BMNH 7994/7995, TMP 81.6.1, FMNH PR2081 ("Sue")
Gracile: AMNH 5027, LACM 23844, MOR 555, BHI 3033 ("Stan")

The assessment of whether the robust morphotype was male or female was based 
upon the divergence of the ilia.  The robust specimens SEEM to show wider 
hip-bones. (No prizes for guessing why!)

However, Chris Brochu is correct: we need a good morphometric study to 
determine if there REALLY are two morphotypes, or whether the specimens just 
blend into one another.


Tim

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