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Re: crocodile reversed or normal




I'll take a stab at this:
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).
Anyway, dinosaurs have croc-reversed ankles (as do all other Ornithodira). I believe that some of the primitive pseudosuchians (sensu Gauthier) also have croc-reversed ankles (e.g., Erpetosuchidae), and you dinosaurologists correct me if I am wrong, but I believe Family Ornithosuchidae may also have croc-reversed ankles. If this is true (will have to recheck on this), I'm not sure why Ornithosuchidae is included in Crurotarsi, but could be another one of those cladistic nomenclatural quirks.
It is all rather confusing, but the croc-normal ankles ("cross ankles") apparently only occur in crocodylomorphs and other "advanced" Pseudosuchians (but not the most primitive ones). And to clarify, I am talking about Pseudosuchia sensu Gauthier (not Pseudosuchia sensu Benton, which most people call Suchia).
Boy, I sure would hate to have to explain all this to a class of college undergraduates. I can see them all rolling their eyes in disbelief, and I wouldn't blame them one bit. :-)
-----Ken Kinman
********************************************************
From: "Tracy Ford" <tlford@ix.netcom.com>
Reply-To: tlford@ix.netcom.com
To: "Dinonet" <dinosaur@usc.edu>
Subject: crocodile reversed or normal
Date: Tue, 22 Aug 2000 02:52:20 -0700

I?ve a quick question. If Ornithosuchians have crocodile reversed ankles,
why are they pseudosuchians since ?pseudosuchians? have crocodile normal
ankles. I should remember this but, dinosaurs have crocodile normal ankles?
right?

Tracy
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