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Re: recapitulation



In a message dated 98-01-23 01:57:00 EST, zooamy@zoo.latrobe.edu.au writes:

<< The point is well taken that there exists variety amongst the large so
 called "typical" theropod teeth.  Nevertheless I don't see any evidence
 that all are derived independantly from an unserrated ancestor.>>

There are enough differences among the teeth of the different groups to render
the hypothesis of a common origin for serrated theropod teeth questionable. In
this, I see more evidence against the common-origin hypothesis than for it.

<< I don't
 know if there is any evidence for unserrated maxillary and dentary teeth
 in any sized theropod outside the Maniraptoriformes (premaxillary teeth
 seem to be a different story). What we really need are some more
 ontogenetic series. The only good one I could find in the literature was
 that of Rio... er sorry, Coelophysis. Very small specimens of this appear
 to have teeth just like those of the adult, no basal constriction here.
 Unfortuneately I couldn't find any word in Colbert's description on wether
 the really tiny individuals had serrations on their max teeth or not.  >>

Speaking of unserrated teeth, I'm pretty sure the small theropod
_Archaeornithoides deinosauriscus_ had such. Also, I recall a paper by
Whetstone & Martin that favorably compares _Archaeopteryx_ and croc
teeth--putting unserrated teeth with constricted bases into an unquestioned
outgroup of dinosaurs and birds and thus at least raising the possibility that
the common ancestor of crocs, dinos, and birds had unserrated teeth with
constricted bases. Martin in particular published photos showing considerable
similarity in detail between croc and _Archaeopteryx_ teeth.