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Re: Cretaceous taeniodont



I have often wondered why there are no unambiguous examples of fossorial
non-avian dinosaurs (and no, I don't consider _Mononykus_ to be an
unambiguous example of a burrower/tunnel dweller, although it certainly
was a curious critter) .  Theropod forearm morphology would seem to be
easily adaptable for burrowing.  In the 180 million years that non-avian
dinosaurs ruled the surface world, we have yet to discover even a single
species that is unambiguously** a plutonian (I made that word up).

This doesn't appear to be a matter of competition for a niche.  Consider
that mammals and lizards both inhabit and exploit the subterranean world,
and both have done so since at least the mid Mesozoic.

** = such as: long, wide scoop-like robust unguals; robust humerus;
robust radius; robust ulna; robust metacarpals; greatly shortened
hindlimbs; limbs able to splay to the side of the body; *small* body;
elongated trunk (mid-body); small diameter orbitals (eye sockets).

<pb>
--

On Fri, 09 Apr 2004 16:31:41 -0500 "Tim Williams"
<twilliams_alpha@hotmail.com> writes:
> Eric Martichuski wrote:
> 
> >  There would, in fact, be selection pressure _against_ being 
> larger,
> 
> Unless your chief predator was a flying bird.  Birds have to stay 
> below a 
> certain weight threshold if they want to be able to fly.
> 
> 
> Tim
> 
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