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Re: _Liaoningornis_

Thomas Holtz wrote:

>Above the level of Archaeopteryx, it becomes easy: a big keeled sternum, the
>presence of a pygostyle (the shortened fused tail of birds), loss of a bunch
>of dorsal vertebrae to the sacrum, and related features.
>Archaeopteryx, however, is so phenomenally primitive, it is difficult to
>distinguish it from non-avian forms.  Only a few features (not found in
>dromaeosaurids) unite it with later birds.

Out of curiosity, just what are the features not found in dromaeosaurids
that unite it with birds (and do any other dinosaur groups share these
features - i.e. are these features unique to birds and Archae)?


cnedin@geology.adelaide.edu.au                  nedin@ediacara.org
Many say it was a mistake to come down from the trees, some say
the move out of the oceans was a bad idea. Me, I say the stiffening
of the notochord in the Cambrian was where it all went wrong,
it was all downhill from there.