Re: Details on Ricardoestesia isosceles

["Tim Williams" <twilliams_alpha@hotmail.com>]

Ken Kinman wrote:

>     If Ricardoestesia were on the order of 2 meters in length, I wouldn't
> think they would be all that gracile (that only jaws would survive).

Nevertheless, only the jaws and teeth *have* survived.  The situation may be 
similar to that of the caenagnathids.  Many isolated caenagnathid dentaries 
are known - far more dentaries are known than any other elements assigned to 
this group.  Similarly, hypsilophodontids of southeastern Australia 
(_Qantassaurus_, _Atlascopcosaurus_, _Fulgurotherium_) are known only from 
dentaries and/or femora.

How's this?  The animal dies.  The carcass is ripped apart by carnivores who 
wolf down the juicy bits.  The bones are left, strewn across the Cretaceous 
landscape, to be stomped on by hadrosaurs and gnawed on by scavengers.  Then 
comes a heavy rain and washes the bones into a nearby river.  By this time, 
the only bones left intact are the lower jaws, which are more robust (or 
perhaps less delectable to a carnivore) than the rest of the skeleton.  
These bones end up on the riverbed, become fossilized, and are discovered 
65-70 million years later by a large-brained bipedal furball with a pick and 
sunglasses.

This scenario is unlikely for a fallen 30-ton titanosaur.  But for a 
slender-limbed, 1-to-2m-long oviraptorosaur or bird (or hypsie), only the 
most resilient bones could sometimes avoid being ground into Mesozoic dust.

>     Have such indented teeth (waisted?) been found in other non-avian
> theropods?

Assuming that the indentation of the crown is the same as the constriction 
of the tooth between the crown and the root described in birds (and, as far 
as I can see, it is difficult to tell from the figures), then, yes, waisted 
teeth have been reported for _Microraptor_, troodontids, and 
_Pelecanimumus_.  (And segnosaurs/ therizinosauroids too?)


Tim


------------------------------------------------------------

Timothy J. Williams

USDA/ARS Researcher
Agronomy Hall
Iowa State University
Ames IA 50014

Phone: 515 294 9233
Fax:   515 294 3163

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