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Re: Non-avian Uncinates



Dino Guy and Computer Gal wrote-

> I know that a few people (Gregory S. Paul, for one) have remarked that
> dromaeosaurs and oviraptorosaurs have uncinates, even though they are
> not present in the fossils of non-ornithurine birds.

The latter statement is untrue.  Confuciusornis has uncinates (Chiappe et
al., 1999), as might Changchengornis.  The condition in Jibeinia is unknown,
although Protopteryx is said to lack them.  Although it is often said that
enantiornithines don't have uncinate processes, very few specimens are
actually complete enough to tell this.  Most well-preserved enantiornithines
(Concornis, Eoalulavis, Spanish nestling, Sinornis, Cathayornis,
Neuquenornis, Boluochia, Longchengornis, Cathayornis? caudatus,
Cuspirostrisornis, Largirostrornis, Nanantius? valifanovi) have only a few
scattered ribs preserved at most (or are broken in that area, like Sinornis)
and often preserve small structures that could easily be uncinates, although
they could just as easily be sternal ribs or dorsal rib fragments.
Liaoxiornis appears to be an enantiornithine without ossified uncinates, but
several features suggest it is juvenile, which may explain their absence.
Details are unavailable for Eoenantiornis.  Only Iberomesornis is well
enough preserved to say there were probably not ossified uncinates present.
However, uncinates are only known from one Velociraptor specimen, and others
with fairly well preserved rib cages (IGM 100/982) do not show definite
uncinates.  Thus, it is possible Iberomesornis did have them.

Mickey Mortimer