RE: Protoavis Status

[Tim Williams <twilliams_alpha@hotmail.com>]

Manuel <mparrado@peoplepc.com> wrote:


> Can anyone tell me what is the current concensus among the paleontological 
> community as to the origin of the bones contained in this controversial 
> fossil material as well as the phylogenic position of protoavis?

To cut a (very) long story short... the consensus among vertebrate 
paleontologists is that _Protoavis_ (from the Late Triassic of Texas) is not 
a bird.  I intend no disrespect to Sankar Chatterjee, but recent discussions 
of this taxon in the scientific literature are highly skeptical that (a) 
_Protoavis texensis_ is a bird; (b) any of the _P. texensis_ material shows 
unambiguous flight adaptations; and (c) all the material assigned to _P. 
texensis_ in fact belongs to a single species.  For example, some cranial 
material and cervical vertebrae might come from a drepanosaurid; and other 
cranial material and some limb material may pertain to a theropod.  One 
researcher has been heard to remark, "It seems to be a fauna, not a taxon".

Unlike _Archaeopteryx_, none of the _Protoavis_ material was found in 
articulation, and individual elements were found spread over a wide area in 
two stratigraphic levels.  Many skeletal elements are very poorly preserved, 
and their identification as this-or-that element is open to interpretation.  
Unsurprisingly, no evidence of integument (e.g., feathers) is preserved.

I would add that there is a possibility that *some* of the _Protoavis_ 
material may actually be avian.  (If therizinosaurs lived in the Early 
Jurassic, why not birds in the Late Triassic?  But then again, the 
identification of _Eshanosaurus_ as a therizinosaur is also problematic.)  I 
would currently rate this possibility as an outside chance.



Tim

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