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Re: Protoavis?

At 12:32 PM 10/16/97 -0600, Jeff wrote (twice, it seems...):
>>>     However, the reason that most paleontologists haven't accepted
>>>_Protoavis_ as the ancestor of birds is two-fold; the speicmen is
>>         No more or less so than _Unenlagia_, IMHO...
>      But quite a bit less so then Archaeopteryx. [or]
>      But quite a bit more then _Archaeopteryx_, _Deinonychus_, 
>_Velociraptor_, _Troodon_...  
        True enough, but Chatterjee is not offering his scenario as an
either/or situation. My point was that _Unenlagia_ is happily accepted, and
_Protoavis_ is not. Now, the pivotal point is that U. is CRETACEOUS, and P.
is TRIASSIC. That is kinda wacky. However, the anatomical evidence should be
considered first, and then the stratigraphy applied, rather than the
reverse. Stratigraphic information is important, but since our knowledge of
the stratigraphic relationships of animal groups is guided by their
phylogeny, the stratigraphy should not, IMHO, be used to a priori weight
against biological conclusions.
        Let me make it clear that I am *NOT* advocating Dr. Chatterjee's
theories on _Protoavis_, nor am I willing or able to argue these points. I
do think, however, that Dr. Chatterjee has been treated unfairly on this
issue. Hopefully his new book will allow for a meaningful evaluation of the
evidence and his interpretations of it, so that we can once and for all bury
the ugliness surrounding this issue where it belongs.

>Besides, there is a lot
>more material availible for theropods then there is for Protoavis.
        Until demonstrated otherwise, _Protoavis_ should, IMHO, be
considered as *at least* Theropoda incerta sedis. The dichotomy which your
statement implies between _Protoavis_ and "theropods" is forced, artificial,
and only contributes further to misconceptions about Dr. Chatterjee's
interpretations of the fossils.

>Compare the amount and quality of material availible for Deinonychus,
>Velociraptor, even Troodon, with the one scrappy specimen of Protoavis.  A
        The last officially reported number (to my knowledge) was two specimens.
        I have seen these specimens, as have several others who work down
here, including one individual with several years experience as a preparator
at a major museum. The specimens are NOT "scrappy". They are incomplete,
yes, however, the presence of:
        and partial...
                -dorsal vertebral column
                -forelimb girdle
                -pelvic girdle
        (and I believe other parts) is *NOT* the sort of assembledge which
is usually termed "incomplete" in the literature. The bones are wonderfully
preserved (and exquisitely prepared), and are not "smooshed" (contra
Gauthier). Yes, they are difficult to interpret. If they weren't,
paleontology would be pretty dull...
        In retrospect, _Protoavis_ may be more complete than _Unenlagia_...

>lot of the bird-like theropods may be just as scrappy as Protoavis, but we
>have more of them, more people have accessed and have examined them,
        They've been around longer. Within obvious budgetary constraints,
this problem can be rectified if more workers can bear to subject themselves
to West Texas.

>and many other types are represented by considerably better material.   
        Once again, you force the unproven distinction between _Protoavis_
and theropods.

>>         O.K.: TIME OUT. I have not read the origional _Protoavis_ article
>> completely (no time), but I know for a fact that Chatterjee currently
>> believes that _Protoavis_ *is* a theropod. Period.
>     But does Currie?
        With all due respect to Dr. Currie, who is a fantastic scientist and
a model for all of us who wish to someday persue the discipline of
paleontology as professionals, does he have to accept it before it is a
theropod? Certainly, his word carries great weight, and a definitive
statement from him would have a profound effect on the resolution of this
question, but is he the ultimate arbiter of phylogeny?
        For that matter, I thought that was Dr. Holtz's job... ;)

>I don't think that he does, or at least not a
>maniraptorian; someone with the article handy might check on that.    
        That would be good. I'm sure Dr. Currie would rather not be
mis-paraphrased. :)

>In any case, even if he DOES share Chatterjee's opinion that Protoavis is
>a theropod, he still lends more weight to troodontids, and to a lesser
>degree dromeosaurs.
        This is true, and is important information.

    Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409-1053
        "There's a fine line between stupid and clever."  -- Spinal Tap