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Re: ornithosuchids



Jaime,
The definition of Crurotarsi (the only one I know of) which I am going by *does* definitely depend on Ornithosuchus. Sereno 1991 (p. 27) gives the following definition of Crurotarsi: "Crurotarsi includes Parasuchia, Ornithosuchidae, _Prestosuchus_, Suchia, and all descendants of their common ancestor."
Therefore, if Ornithosuchidae is closer to birds than it is to crocs, then Crurotarsi (as defined by Sereno himself) is either paraphyletic or polyphyletic (and must be abandoned under a strictly phylogenetic taxonomy)---unless there is another definition that I don't know about, or there are plans to change the definition.
There are still plenty of workers out there who believe Ornithosuchids are closer to birds than to crocs, who do not take Sereno's topology for granted, and thus I feel the need to take a very hard look at Crurotarsi and its purported synapomorphies.
---Anyway, Happy Labor Day,
Ken
******************************************* 
From: "Jaime A. Headden" <qilongia@yahoo.com>
To: dinosaur@usc.edu
CC: kinman@hotmail.com
Subject: re: ornithosuchids
Date: Mon, 3 Sep 2001 03:13:49 -0700 (PDT)

Ken Kinman (kinman@hotmail.com) wrote:

<"Ornithes" would not be necessary. If Pterosaurs are non-archosaurs, then we can use: (1)
Ornithosuchia (if ornithosuchids are closer to birds than to crocs); or (2) Avemetatarsalia if
ornithosuchids are closer to crocs than to birds. That is another reason why Crurotarsi (and its
purported "synapomorphies") need to be carefully reevaluated, and the sooner the better. Where
Ornithosuchidae fits in is still very uncertain and very controversial.>

The definition of Crurotarsi does not depend on Ornithosuchus, and thus neither does its
content. It's wise not to confuse the two. However, I beleive you are not an advocate of formulaic
definitions of clades, or else why the continuing advocacy of concept based usage? Anyways...


=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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