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Re: Quo vadis, T. rex? [long]



At 08:18 PM 2/6/96 -0500, Jeff Poling wrote:
>At 04:40 PM 2/6/96 -0700, Jeffrey Martz wrote:
>>
>>>    Why?  Right now there are damn few skin impressions of theropods that can
>>> conclusively show anything.  Absence of evidence is not (necessarily)
>>> evidence of absence.  Given that 1) Dromaeosaurs were very closely related
>>> to Archaeopteryx and 2) Archaeopteryx had feathers it makes sense that all
>>> maniraptorans had feathers.
>>
>>     Why?  You are assuming that feathers evolved in the common ancestor 
>>of all maniraptorans.  It could just have easily have been a later 
>>innovation of one small group, which eventually led to Archaeopteryx.  
>>Its largely a question of when feathers first appeared, something that is 
>>NOT known.
>
>   That's right.  It could just have easily been a feature of
>archaeopterigians, rather than the common ancestor of maniraptorans.
>However, what you said in your first post was "Assuming that any theropod
>except Archaeopteryx had feathers is a much bigger assumption" implying that
>that one theory carried more weight than the other.
>
>   In any case, until _Pelicanimimus_ is fully described and put through
>peer review, I think it looks more likey that at least the common ancestor
>of ornithimimids and maniraptorans, rather than just the common ancestor of
>maniraptorans, had feathers or were well on their way to it.
>
>   It just crossed my mind that since pterodactyls had hairlike structures,
>maybe proto-feathers are plesiomorphic for archosaurs....

   ...and, of course, another reason why, in my mind, it's likely that they
all had feathers is the question of insulation on the smaller dinos.

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