Re: Velociraptor footprints

[smithjb@sas.upenn.edu (Joshua Smith)]

Dinogeorge@aol.com wrote:
> 
> In a message dated 97-08-04 09:49:19 EDT, smithjb@sas.upenn.edu (Joshua
> Smith) writes:
> 
> << In this discussion of thousands of theropod footprints here and there and 
>  everywhere being correlated to this skeleton and such and such taxon here 
>  and there, you are neglecting to account for the fact that there are NO 
>  CONFIRMED THEROPOD FOOTPRINTS ANYWHERE. >>
> 
> There is Tyrannosauropus (or is it Tyrannosauripus?--my reference is not with
> me in San Diego yet), which is based on a large print that can only be that
> of Tyrannosaurus, the only dinosaur capable of leaving a print of that size
> and shape.
> 
        I think it is _Tyrannosauripus_.  My reference is here somewhere...

        Oh come on, George.  Ten years ago _Tyrannosaurus_ was the 
"largest" theropod, too.  Just because there isn't another  theropod in the 
current fossil record from the New Mexico Maastrichtian that is large 
enough to create _Tyrannosauripus_ does not mean that one didn't exist.  
_Tyrannosaurus_ is the only theropod WE CURRENTLY KNOW OF that is capable 
of making that track. That means nothing.  Don't believe me?   I give you 
the Newark Supergroup "theropod" ichnotaxon _Eubrontes_ Hitchcock, 1845.  
There is no animal from the Newark Supergroup in the collections of any 
institution that could have created that footprint.  However, I have the 
measurements of 247 of those footprints sitting here in my computer.  I 
guess there was probably a _Eubrontes_ sized trackmaker out there 
somewhere...

Perhaps I just beat that point a bit to death, but I just think that 
these inferences drawn on the basis of "negative evidence" are very 
dangerous things to do in paleontology.  I can cite three references 
where colleagues have used this same idea to justify their hypotheses 
that _Eubrontes_ tracks were made by prosauropods: i.e., there are not 
theropods large enough to have made them known in any collections.  
So what?  That DOESN'T mean they did not exist.  Before _Ceratosaurus_ 
was discovered, there were no theropods in any collections with horns on 
their noses...



-- 
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Josh Smith
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