Re: Ichnotaxa (was RE: dino tracks near Syracuse?)

["Steve Brusatte" <dinoland@lycos.com>]

On Tue, 4 Dec 2001 09:23:10   
 Andy Farke wrote:
>It all depends on how you want to use your track data. As I understand it,
>invertebrate ichnofossils are mainly used to infer environment or facies
>(hence, the Cruziana facies, Skolithos facies, etc.). We have Skolithos
>going back to the Cambrian--it's almost certainly not the same animals
>making Skolithos today, but ones with similar behavior and general body
>form. You can have a wide variety of animals (different phyla, even) making
>similar ichnofossils.
>
>To me, it's a different case when working with vertebrate (especially
>dinosaur) ichnotaxa. They're more often used for paleoecological,
>behavioral, or biomechanical studies, in which it's desirable to know the
>precise identity (or a reasonable approximation) of the track maker. Simply
>knowing that dinosaurs were usually just walking across a mud flat isn't
>terribly useful. . .

Well, I suppose.  It just depends what type of study you are conducting.  In 
some cases knowing that  1) dinosaurs were present in the environment and 2) 
the environment was a mud flat may provide some use.  This would only apply in 
specific geological studies that are trying to pinpoint exactly what type of 
environment a certain outcrop/unit represents.  

I do agree that invertebrate trace fossils, especially Cruziana, are easier to 
use when implying environment.  Cruziana traces are pretty unambiguous and 
provide a nice datum: obviously they were made on the seafloor, and very 
possibly by trilobites.  

But, vertebrate body fossils themselves are much better for interpreting 
biomechanics and behavior (but not necessarily paleoecology).  Obviously, it's 
much easier to deduce and study the biomechanics of something with a preserved 
skeleton-covered with muscle attachment scars and full of teeth-than of some 
invertebrate preserved one-dimensionally in a concretion.  The same holds true 
for vertebrate ichnofossils.  Eggs, gastroliths, coprolites, tracks, etc. can 
all give a lot of good behavioral evidence.  Unfortunately, it is near 
impossible to unequivocally equate many trace fossils with their makers.

Steve

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