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Re: tooth question

Phillip Bigelow wrote:

>> 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.

smithjb@sas.upenn.edu (Joshua Smith) wrote:

> This doesn't really hold in the Lance Formation, which is almost
> no different from the Hell Creek.

It doesn't?  In what context?  How many undisputed Albertosaurs are
known from the Lance Formation? I'm not claiming that you are wrong,
but I would like the source of your information (I am sort of collecting
information on this topic). Keep in mind that the Lance and Hell Creek
Formations are *late* Maastrichtian, not early Maastrichtian.

There is some information that suggests that the respective
faunas are not identical between the two formations.  This is
particularly true of fresh water pelecypods.  Of course, to a
paleoecologist, "identical" is a loaded word. Paleontologists can only
sample an extinct ecosystem; they can't know everything about it (which
is also true of modern ecosystems).

Russell, L. S. 1976. Pelecypods of the Hell Creek Formation (Uppermost
Cretaceous) of Garfield County, Montana. Canadian Journal of
Earth Science, vol. 13, pp. 365-388. (see page 367 for a short comparison
of the two formations).