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Re: Elmisaurids (was Re: Dinosaur Web Pages' Re-Opening)

At 08:09 PM 9/4/97 -0400, George wrote:
>>>one. _Mononykus_ can't be a bird because, like _Avimimus_, it doesn't
>>>have an avian metatarsus; it has an arctometatarsalian metatarsus.
>>         As do the non-arctomet elmisaurids. Indeed, there seems to be a
>> tendancy in all coelurosaurs towads a compressed MT III, and in at least two
>> groups, towards a more slender metatarsus. >>
>All this means is that elmisaurids aren't birds, either. The
        Why, because they could not have separately evolved the
arctometatarsalian condition? It has already been suggested that the
condition is convergent in oviraptorsaurs and arctometarsalians proper. If
the arctomet condition is convergent in elmisaurids anyway, then no matter
whether the tarsus narrowed before or after flight evolved, it takes the
SAME number of steps. 

>arctometatarsalian metatarsus is actually >derived< with respect to the avian
>metatarsus (_Archaeopteryx_ does not have an arctomet metatarsus).
        So? This just means that since earlier birds have a more "primitive"
metatarsus, it may have even been *easier* for them to develop the
arctometatarsalian condition.

>It may indeed have arisen more than once.
        A decent bet.
    Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409-1053
               "Not the One..." -- Zathras (not Zathras)