[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

RE: Who says dromaeosaurs can't fly?



--- Ronald Orenstein <ornstn@rogers.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 <keesey@bigfoot.com>
=====> The Dinosauricon <http://dinosauricon.com>
=====> BloodySteak <http://bloodysteak.com>
=====> Instant Messenger <Ric Blayze>
=====

__________________________________________________
Do you Yahoo!?
Yahoo! News - Today's headlines
http://news.yahoo.com