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Re: Teeth of Moroccan dinosaurs



At 02:30 PM 3/4/99 +0100, Thomas Hammann wrote:

>I wonder about the (relatively) high number of teeth from Carcharodontosaurus 
>saharicus and Spinosaurus spec. for sale. Whenever I see such a tooth from 
>Morocco I've doubts if it is authentic because there were found only a few 
>complete skeletons of these species.
>
>Who knows more about these teeth? How is it possible that there are so many of 
>them?

Dinosaurs do shed teeth continuously throughout their lifetimes, as do most
non-mammalian vertebrates.

Also, isolated teeth have a much better chance of being buried, fossilized,
and recovered than complete skeletons: that is why most dinosaur-bearing
formations have lots of teeth but fewer skeletons.

Also, _Carcharodontosaurus_ and _Spinosaurus_ both have very distinctive
tooth morphologies, and are known from the same geologic units that these
teeth are recovered from.  The identity of these teeth are fairly secure.

Not at all secure are the supposed "Albertosaurus" teeth from Morocco (these
are non-tyannosaurid teeth, but who knows what they are from:
??_Deltadromeus_, maybe??), or so-called _Deltadromeus_ and _Elaphrosaurus_
teeth.  We don't know *what* the skull of _Deltadromeus_ was like: it hasn't
been found (ask Josh Smith or Matt Lamanna about their photograph of the
_Delta._ skull sometime... :-), so we don't know what its teeth are like.
(The reasons I questionably suggest that the "Albertosaurus" teeth of
Morocco might be _Deltadromeus_ are a) these teeth aren't from
_Carcharodontosaurus_ or _Spinosaurus_ and b) _Deltadromeus_ is known from
these beds).

The "Elaphrosaurus" teeth are even more problematic.  Not only do we not
know what _Elaphrosaurus_'s skull (and hence teeth) were like, but (even
worse) _Elaphrosaurus_ isn't even from the same time and place as these
teeth!!  _El._ is from the Tendaguru (Late Jurassic of Tanzania).  Some
mid-sized theropods from the mid-Cretaceous of northern Africa have been
referred to the genus _Elaphrosaurus_, but there is in fact no reason to do so.

Finally, Morocco markets are chock full of fossils, geological materials
being a major item in the tourist trades.  Some of the Moroccan material are
clearly fakes (S.J. Gould discussed this sometime a year or so ago in an
essay in _Natural History_).  Plenty of the specimens, though, are real, and
the dinosaur teeth are among these.  There's lots of land their to collect
teeth from, and a good reason (extra money) to do so.  Unfortunately this
sort of fossil mining isn't very helpful scientifically, and Sereno has
mentioned the (sometimes fatal) human cost of this method of prospecting in
various talks concerning his expeditions to northern Africa.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661