RE: I don't think this made it onto the list: Androgynous Rex

["Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>]

> From: owner-DINOSAUR@usc.edu [mailto:owner-DINOSAUR@usc.edu]On Behalf Of
> bucketfoot-al@justice.com
>
> 
> So I guess this means we go back to observing that
> there appear to be a gracile and a more robust version
> of TRex, and then we flip a coin as to which is male
> and which is female?

Ummm, not even that... First of all, we have yet to get a published account 
demonstrating statistically that there ARE gracile and robust morphs. (That is, 
that there are two distinct clusters rather than a continuum). (Incidentally: 
such a study is on its way).

If so, than than the robust ones are probably female, since "Bob" (the specimen 
with the medullary bone, a tissue type associated with ovulating female 
archosaurs today) is on the robust end of things.

> (How come I have never heard this kind of speculation
> about the Triceratops, or any other dinosaur besides
> TRex anyhow?)  

Because T. rex is the center of the universe... :-) Honestly, there are other 
studies of possible sexual dimorphism in dinosaurs (pachycephalosaurs, 
ceratopsids, etc.), but they tend not to get the public attention that T. rex 
studies do.

                Thomas R. Holtz, Jr.
        Senior Lecturer, Vertebrate Paleontology
Department of Geology           Director, Earth, Life & Time Program
University of Maryland          College Park Scholars
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