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RE: Jane The juvy T. rex



> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
> Henry Mendoza
> Sent: Saturday, July 09, 2005 8:51 AM
> To: Dinosaur mail list Dinosaur mail list
> Subject: Jane The juvy T. rex
>
>
> I expected to hear a lot more from everyone about the
> unveiling of Jane last week. How come no one has
> commented on it?

Because we weren't there, perhaps? Maybe Waiting For The Symposium might be a 
good idea?

> That issue has been
> uncharacteristically quiet. Does anyone know what
> Bakker, Larson, and Currie are saying about the whole
> thing?

What do you think?  Camp A: primarily typological, but not strictly: Bakker, 
Currie, Larson, Hurum - Nanotyrannus is a distinct
taxon, and Jane is the most complete specimen.
Camp B: generally lumpers, with an emphasis on allometry: Holtz, Carr, 
Williamson, Paul, Brochu - "Nanotyrannus" is a growth stage
of T. rex, and Jane is the most complete specimen.

> I mean when this little creature was first found the
> rave was that it was a Nanotyrannus. In personal comm.
> with Pete Larson he was strongly on the side of it
> being a Nano.
>
> So what's the buzz?

Peter Larson is very convinced on the reality of Nanotyrannus as a distinct 
taxon, and of Jane being a Nano.

> I personally have looked at quite a few teeth that are
> Nano sized , yet are proportionately robust with large
> serrations like Adult T. rex teeth.

Different tooth positions. Posterior teeth of a big individual of T. rex are 
the same size as anterior teeth of the a small
individual of T. rex. Tooth size without tooth position information in mildly 
heterodont theropods like Tyrannosaurus are not
informative about body size of the individual in the middle part of the 
tooth-size range.

> Jane supposedly
> has very bladed crowns and finer serrations. Can
> anyone comment on this paradox?

Short answer: ontogeny. Longer short answer: mediolateral width of teeth in 
tyrannosaurids (and some other theropods) scale with
positive allometry with respect to tooth crown height and to anteroposterior 
length.

                Thomas R. Holtz, Jr.
                Vertebrate Paleontologist
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