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Re: tooth question



rtbuckle@fuse.net (ron buckley) asked of the list:


> Hi, I have been trying to get a better understanding of the difference

> between a tyranosaurus rex and an albertosaurus tooth. I have looked
in
> Curries "Encyclopedia of dinosaurs", another of his books with the
> Theropod teeth from the Judith River Formation of Southern Alberta
> Canada, and in Gluts "The Dinosaurs The Encyclopedia". I have found
that
> the Tyranosaurus rex probably has a bigger girth to the tooth.

FWIW, scaling differences aren't always reliable diagnostic characters.
It would work only if you *knew* that your specimen was from an adult
(and with an _Albertosaurus_-size tooth, you don't know for sure).

> Is there
> a difference in the serration structure?

Nope.  Both genera have similar shaped carinae, and the serrations on
both genera resemble cubes that are laying on one edge.  Both genera
also have similar "blood grooves". _Albertosaurus_ teeth may be a bit
more laterally compressed, but this would only be noticable if you had a
tooth of each genus in front of you.
Do you have Abler's _Paleobiology_ paper on T. rex tooth morphology and
bite-mechanics?  If not, you should get a copy. It's a classic.

> I would appreciate any
> imformation or sources of imformation to increase my knowledge. Thanks

> in advance. Ron

You might be interested to know that there is a growing consensus of
opinion that in many of the *latest* late Maastrichtian formations in
North America, the only large tyrannosauroid present was T. rex.  This
is particularly true in the Hell Creek Formation, where Greg Paul's
_Albertosaurus gracilis_ is now believed to be a juvenile T. rex.  So,
at least for the Hell Cr. Formation, T. rex was the only big guy
around.  There is also a (more slowly) growing consensus that
_Nanotyrannus lancensis_ is a still-younger juvenile _T. rex_.  Nothing
officially published yet, so it's sort of up in the air.  That leaves
_T. rex_ and the two _Aublysodon_ species (which are much smaller) as
the only undisputed tyrannosauroids in the Hell Creek Fm......and
_Aubly's_ teeth are very distinctive.
Moral of the story:  If it's a "big ripper of a tooth", and it's latest
late Maastrichtian in age, it probably fell off of a _T. rex_.
_Albertosaurus_ and _Gorgosaurus_ may have still been around in the
early Maastrichtian, but after that, the time of their ultimate demise
gets a little foggy.
                                <pb>

p.s.  It's happening again.  Everytime I post something, I get hit with
spam from a yahoo.com address and an ibm.net address.  Is this happening
to anyone else?