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Re: Details on Ricardoestesia isosceles

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

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?)



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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