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Re: Coelurosaur ischium unique?
In a message dated 12/19/01 11:13:39 PM Eastern Standard Time,
> Does the coelurosaur ischium always possess at least two of the
> following three features? Each of these features is occasionally lacking
> in a few coelurosaurs, but I believe that all coelurosaurs have at least
> of the three (and most would have all three):
> Ischium (1) reduced to less than 2/3 length of the pubis; (2) lacking
> an ischial foot; and (3) possessing a prominent, triangular obturator
> process (placed more than 25% down the ischial shaft).
Tyrannosaurs and ornithomimosaurs generally have ischia more than 2/3 the
length of the pubis, and at least some specimens of each have obturator
processes placed less than 25% down the ischial shaft.
> And the flipside (converse?) of this question is---Are there any
> non-coelurosaurs which also display at least two of those three ischial
Not sure. Coelophysoids can't really be said to have obturator processes at
all. I am pretty sure I have never seen a non-coelurosaur with the classic,
_Ornitholestes_- or _Deinonychus_-type triangular obturator process.