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Re: crocodile reversed or normal



On Tue, 22 Aug 2000, Ken Kinman wrote:

>       I think you may be confusing Family Ornithosuchidae with the clade 
> Ornithosuchia.  Due to some quirky cladistic anchoring, Ornithosuchidae is 
> now included in Pseudosuchia (not in sister clade Ornithosuchia).  For this 
> reason I prefer using the term Ornithodira (which I believe still contains 
> the same groups as Ornithosuchia).

Ornithodira and Ornithosuchia are different clades. Ornithosuchia is a
stem group, while Ornithodira is a node group. Under most phylogenies,
these do comprise the same memberships, at least for known specimens.
However, under, for example, the phylogeny on Dave Peters' site,
Ornithodira would actually include all of Archosauria (including
Ornithosuchia), Prolacertiformes, and more!

I agree that Ornithosuchia is a highly unfortunate name. When PhyloCode or
whatever the ultimate PT system will be is simplemented, I personally
wouldn't mind seeing something like this:

Avemetatarsalia == (Neornithes <-- _Crocodylus_)
(Avemetatarsalia being Benton's replacement name for Ornithosuchia, IIRC)

Ornithodira == (_Pterodactylus_ + Neornithes) excluding _Crocodylus_
(Thus invalidating the clade under Peters' phylogeny.)

_____________________________________________________________________________
T. Michael Keesey.........<tmk@dinosauricon.com>.........<keesey@bigfoot.com>
AIM <Ric Blayze>..............ICQ <77314901>...........Yahoo!M <Mighty Odinn>
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