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Re: Archaeopteryx



--- Dinogeorge@aol.com wrote:
> 
> Has a frame-shift been documented in other groups of vertebrates (or 
> organisms), or is this idea something that cladists have cooked up to hide a
> major problem with their avian phylogeny, hmm?

Invalid argument. Because something happens in one lineage doesn't mean it MUST
have happened in others. For example, just because no other vertebrates have
rostral bones does not mean that ceratopsians could not have had them.
At any rate, other types of homeotic shift have been observed. And it's been
shown that digit identity and number are developmentally independent.

> We don't need a frame shift if we consider the notion that there was more
> than one pattern of digits in the theropod-avian manus.

I'd like to point out something that often seems to be missed: even if there
were no frame shift, the "weakest point" is not between traditional theropods
and birds -- it's between avepods and the more basal, five-fingered
saurischians (herrerasaurids, _Eoraptor_). I don't understand why people would
prefer to cut _Aves_ out of its traditional place rather than remove all of
_Avepoda_.

BTW, is there any kind of archosaur with reduced digits I and V?

> I can't tell you how dissatisfied I am with the current crop of 
> theropod-avian cladograms. Everything's circular or tautological, nothing can
> be or has been checked in independent ways. No wonder the ornithologists are
> screaming.

You're free to present your alternative. Last I looked it wasn't radically
different except for nomenclature. How has it changed?

=====
=====> T. Michael Keesey <keesey@bigfoot.com>
=====> The Dinosauricon <http://dinosauricon.com>
=====> BloodySteak <http://bloodysteak.com>
=====> Instant Messenger <Ric Blayze>
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