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Euparkeria (was Re: Astro turf)

At 12:34 PM 5/4/97 -0600, LN Jeff wrote:

>    How controversial is Paul Sereno's placement of _Euparkeria_ at the
>base of Archosauria, its dissasociation from the ornithosuchids, and the
>placement of the ornithosuchids with (Gauthier's) pseudosuchians to form
>Cruotarsi?  These last two seem pretty radical based on the little
>research I've done, and I was curious what other people's take on it was.
>Sereno 1991 is the most up to date thing on it I've read on "thecodonts"
>(even _I_ don't mind using quotation marks for THAT paraphyletic group).

Euparkeria is pretty convincingly basal within Archosauriformes, and I don't
think anyone would be terribly surprised with it as a basal ornithosuchian,
a basal pseudosuchian, or an archosauriform outside of Archosauria proper.
It's association with Ornithosuchidae was never based on particularly strong
positive evidence.

Those of us using phylogenetic taxonomy would argue that evidence that
Ornithosuchidae is closer to crocs than to birds doesn't mean that an
explicitly defined taxon name like Pseudosuchia (crocs and all taxa closer
to crocs than to birds) vanishes up in smoke.  Pseudosuchia remains, and
Crurotarsi will either be considered a junior synonym or a node within the
stem-based Pseudosuchia.

Gower and Juul are two other workers with recently published basal
archosauriform phylogenies (Phil Trans Royal Society and
Paleontologia(-graphica? whatever) Africana, respectively, if memory serves).

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:th81@umail.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661