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Re: Incisivosaurus gauthieri



--- "Thomas R. Holtz, Jr." <tholtz@geol.umd.edu>
wrote:
> This is a good week for dinosaurs!!
> therizinosaur-like maxillary and dentary teeth *with
> wear facets*.

Is it not true that Incisivosaurus would also give us
a fairly good model of how a basal therizinosaur or
the common ancestor of the therizinosaurs and the
oviraptorosaurs would have looked? In light of this
discovery it is all the more likely that the mandible
of Eshanosaurus that was original reported in Nature
could be that of a therizinosaur? Eshanosaurus sure
had lanceolate teeth and came out fairly as a basal
therizinosaur in the analysis of Xu but was it not
from the lower Jurassic. This would mean that the
Therizinosaur-oviraptorosaur split minimally occured
in the Lower Jurassic itself. Would this mean the
Yixian forms were remarkably stable as they were
retaining features that one would expect of the Lower
Jurassic. Does this not look like an anachronism of
the strangest type. Or are we thoroughly mistaken
regarding the Yixian age? As a corollary we should
have Late Triassic or at least early Jurassic
tyrannosaurs, deinonychosaurs and other assorted less
derived forms. This shows that these clades were
remarkably stable and have a long cryptic history that
we are completely blind to.
_EA

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