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Re: Carcharodontosaurids and Abelisaurs



T. Mike Keesey wrote:    
>The cladogram placed _Giganotosaurus_ closer to abelisaurs than to
>tetanurines! Furthermore, I think in the section on abelisaurs there was
>some mention of carcharodontosaurids possibly being related to abelisaurs.
>What's going on here? Carcharodontosaurids are carnosaurs, right?
       "I think you'll find that a great many of the truths we cling to
depend greatly upon your point of view."
        Nothing is ever set in stone as far as phylogeny is concerned.
Recall that, nary three years ago, you might have been saying "What's going
on here? Tyrannosaurids are carnosaurs, right?" Just because we have newer,
better methods of generating phylogenetic hypotheses does not mean that
those phylogenies will always be supported by new data. To quote another
great luminary: "[Phylogenetic analysis] is the begining of wisdom, not the
end."
        Lets look at the facts:
        1) Both Abelisaurids and Carcharodontosaurids, are excluding
_Acrocanthosaurus_, have been reasonably well known for only a few years.
        2) Good data on the latter group (courtesy of Drs. Coria, Selgado,
Currie, and Sereno) has only popped in the past year or so, and some of that
has not been published yet.
        3) How many of anybody has gotten to study all of the specimens?
Granted, a lot can be done from descriptions (although maybe not
descriptions published in MacScience journals), photographs, etc. However,
until details of their anatomy are well known, oppinions may change based on
new observations, re-evalutation of other people's characters (when
published), etc.
        4) One of the authors of the _Encyclopedia_ has access to some of
the latest data.
        Of course, somebody famous has been quietly saying this for a while
now. We'll see. Perhaps Dr. Sereno will have someone else to taunt with his
Stooges slides at the next SVP...


>Is someone proposing that tridactyly evolved twice among theropods?
        Is there a complete, articulated Carcharodontosaurid manus? I do not
recall such a thing turning up, but I am notorious for my crack-smoking
binges. Maybe there is one for _Acrocanthosaurus_, but apparently some folks
dispute the association of acro and c'rids.
        On the other hand, what would be so bad about that? If the sickle
claw could evolve twice, I could have no difficulty with the tridactyle
manus evolving twice. Of course, you'd have to show me the evidence first...

        Wagner
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    Jonathan R. Wagner, Dept. of Geosciences, TTU, Lubbock, TX 79409-1053
        "Chimp here does the killing." - Doug Mackenzie