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Re: VALIDITY OF AVES



In a message dated 98-08-13 03:02:38 EDT, dannj@alphalink.com.au writes:

<< Surely you mean that the ancestor of modern birds was with all
 probability an archaeopterygian. The chances of any direct ancestor
 actually being fossilized (preserved, and found) is extremely slim.
 Archaeopteryx may be the "closest thing to an avian common ancestor"
 but it was not necessarily that exact species. >>

If this were true, then Archaeopterygidae would be paraphyletic, since it
certainly doesn't include its descendants, the modern birds. Cladists would
say it is better to define Archaeopterygidae (or a higher taxon than family)
as "all birds closer to _Archaeopteryx_ than to modern birds." This at least
removes the common ancestor from Archaeopterygidae and keeps the group
monophyletic.