Re: New alvarezsaurid

["Matthew Troutman" <m_troutman@hotmail.com>]

>> If some theropods did descend from 
>> early birds, then you would expect _all_ the diagnostic features 
still 
>> to be present. 
>
>Perhaps so, but what if the early bird which gave rise to these 
theropods
>is a basal form even more primitive than _Archaeopteryx_?  Then the
>differences between the anatomy of the theropods derived from the early
>bird and the anatomy of other theropods not derived from the early bird
>would be somewhat less obvious; there would still be some features to
>distinguish the lineages, but not as many as one would see were the
>ancestral early bird of the theropods to be more derived (modern) in 
form.

    I cannot imagine a bird more primitive than "Rahona" or 
Archaeopteryx. It would not be a bird then. Regardless, if there is a 
"bird" in that sense, then many of the same things I have noted would 
still be true ( a creature inbetween Archaeopteryx and dromaeosaurs 
would still have the three tympanic recesses among other things). Other 
"flying dinosaurs" that would spawn off other theropod lineages of 
course have not been found and there is no use speculating on 
phylogenies with them included.

MattTroutman

>-- Ralph Miller III     gbabcock@best.com  
>


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