Re: crocodile reversed or normal

["Ken Kinman" <kinman@hotmail.com>]

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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