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Re: Saltopus... a silesaurid?



2011/5/19 Tim Williams <tijawi@gmail.com>:
> On Thu, May 19, 2011 at 11:50 PM, Augusto Haro <augustoharo@gmail.com> wrote:
>
>> According to a Figure in Sereno 1991 (Memoir of the SVP) on the tarsus
>> of a phytosaur, it was apparent that the "astragalar peg" was scarcely
>> developed, the astragalo-calcaneal articulation being not much
>> different from the common basal archosauriform condition. So,
>> considering phytosaurs as crocodile-normal is partially a "courtesy"
>> with them (as would have say Romer).
>
>
> Well said.  Further, as you know, the "crocodile-normal ankle" is an
> assemblage of characters, rather than a discrete character.  Sort of
> like the "perching foot" of birds.
>
As far as I remember, crocodile-normal, crocodile-reversed, and
mesotarsal refer not to a combination of tarsal characters but to the
shape of the astragalo-calcaneal articulation. Of course, later Sereno
(1991, Memoir) found further ankle characters supporting his
Crurotarsi, including characters from the rest of the parts of the
proximal tarsus. Earlier discussions which recognized these
alternative types focused on the shape of the articulation (e.g.,
Brinkman 1981, in Breviora).