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RE: Who says dromaeosaurs can't fly?
--- Ronald Orenstein <email@example.com> wrote:
> At 03:12 PM 16/09/02 +0000, Brian Lauret wrote:
> >I think we're getting a bit off subject by now.But I do want to give my
> >view on the entire issue.
> >I personally think the earliest evolution of birds may be unresolvable by
> >cladistic methods because I view the earliest bird (this is very debatable
> >of course,it's totally conjectural from my side) as the earliest arboreal
> >dinosaur with at the ability to fly.
> Well, on what basis do you make this assumption? What is an "ability to
> fly", anyway? And why are you defining a taxonomic group on an
> undemonstrable and unmeasurable character (rather than, say, a set of
> reasonably unequivocal morphological features)? It seems to me the problem
> is with your definition of birds, not with cladistic methods. But I don't
> see why cladistics cannot be used to define any taxonomic group including
> all species stemming from a common ancestor, whatever that ancestor was.
Gauthier and de Queiroz 2001 used pretty much this exact same definition for
_Avialae_. Something like: "The first ancestor of _Vultur gryphus_ to possess
wings used for powered flight homologous with those of _V. gryphus_, plus all
of that ancestor's descendants". I don't see how this can be applied with any
precision, though, since it is impossible to know the behavior of extinct
organisms. Some people would include all _Maniraptoriformes_, others wouldn't
even include _Archaeopteryx_. If it's going to be an apomorphy-based
definition, something about forelimb/trunk ratio might work better.
=====> T. Michael Keesey <firstname.lastname@example.org>
=====> The Dinosauricon <http://dinosauricon.com>
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