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VALIDITY OF AVES
<<With recent discoveries and discussion of avian dinosaurs,
flightlessness,etc, our widened conception of dinosaurs to include
birds, is it not time to re-define "birdness" ?>>
<<Is Aves still valid ?>>
<<Is it a polyphyletic grouping resulting from different birdlike
<<Do birds have a common ancester?>>
Yes. The common ancestor is _Archaeopteryx_. No matter which basal
avian phylogeny that you read (whether it supports Sauriurae or
Ornithothoraces) they all stick by the conclusion that _Archaeopteryx_
is the closest thing to an avian common ancestor. Other possible birds
(_Unenlagia_) which may be more "primitive" than _Archaeopteryx_ are
simply too fragmentary to make a detailed case for their position in
<<Are ratites, and kiwis actually birds at all?>>
Let me direct you to Witmer (1991) and Feduccia (1996); previous
arguments against the "birdiness" of these animals have been refuted.
Anyway, all analyses prove that ratites came from avian ancestors.
Lithornithids have been showed by Houde (1988) to be the ancestors of
I'll give a more complete argument later.
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