Re: dino tracks near Syracuse?

["Rob Schenck" <rs7286@albany.edu>]

----- Original Message -----
From: "R. Irmis" <rbi@dana.ucc.nau.edu>
To: <rs7286@albany.edu>
Cc: <dinosaur@usc.edu>
Sent: Monday, December 03, 2001 8:00 PM
Subject: RE: dino tracks near Syracuse?


> <<i dont know about that.  The tracks are from a specific period of time,
so
> that in itself limits the possibilities.>>
>
> Not really...who is to say that they dont belong to a dinosaur not known
> yet.  Also, the only coelophysoid that I know of described from the East
> Coast is Podokesaurus, which was destroyed in a fire (although low quality
> casts exist).  Colbert did synonymize this taxa with Coelophysis, but I
> believe there is a large temporal age difference between the two.
>
> <<I guess you coudl make a case that no ichnofossils can be tied to any
> skeletal specimin, tho that would tend to make the ichnofossils relatively
> useless.>>
>
> I dont follow you here.  Just because trace fossils are not assignable to
> body fossil taxa doesnt make them useless.  In fact, they are the only
> record we have of actually behavior and activity from the animal, and
> through this they can tell us alot.
>

if all we can do is say this is a foot print of a certain age,then all we
can say is that the maker of this foot print had the following
characteristics that we are infering from the footprint.  I am sure that
there are some, but i really dont see ichnofossils being used in cladistic
analysis, or anything of that sort for that matter.  To apply footprints to
any useful biomechanical study, we need to know about the animal that made
it, like leg lenght, weight estimates, etc.  What good is a foot print, if
we arent going to say its anymore than a foot print.  If we cant identifty
it with any certainty to say, _Coelophysis_, then how can we really say that
it beolonged ot theropods, or anything for that mater?  Why, because it has
characteristics that we expect theropods to have?  Then what abou
tcharacteristics that we would expect _Coelophysis_ to have? Howe are you
going to assign it to a group, the diagnosis of which is based on skeletal
elements?  Maybe i am misunderstanding this whole thing, maybe _Grallator_
is  not assigned to any of the skeletal taxons, no matter what level of the
heirachy they are on.  But having said that, then we cant say that its a
dinosaur foot print either can we.



> <<But anyway, very similar tracks are foudn next to specimins of
> _Coelophysis_ in New Mexico.>>
>
> I know of NO such association between tracks and body fossils of dinosaurs
> of any type in the whole Chinle Group.  Care to enlighten me?
>
> <<Although, it seems to me that the _Grallator_ specemin is the senior
> synonym, and if anything we should refer to _Coelophysis_ as having been
the
> junior synonym for it.>>
>
> Please reread Emma R.'s post.  She correctly mentioned that the ICZN
> explicitly states that ichnotaxa and traditional taxa are always kept
> separate, even if we find a body fossil at the end of the track.  The
> reasons for this are two fold: A) Unless we have a body fossil at the end
of
> a track (Mesolimulus in Solnhofen for example), there is no way to assign
> the track to any body fossil taxa, since it may be made by multiple taxa,
or
> belong to one not yet discovered. B) Even if we do find the body fossil at
> the end of the track, there is no way to assure that this is the only taxa
> that makes the track.
>
> <<I guess the only real way to accept older names for fossils like
> ichnofossils is to assume that any association of them with skeletal
> specimens is not possible.>>
>
> This IS what is assumed by ichnologists, and is the most scientifically
> sound method.
>

again i just dont agree with this, i dotn see it as being useful.  I have
heard of footprints being used to support gregariousness in sauropods and
such, but how is this possible if the footprint is in no way associated with
any skeletal taxon?  All we can really say is that teh maker of the
ichnofossils were gregarious, but really, we cant even say that can we.  We
cant say that what appears to be five trackways made by four legged animals
are such, because, wel, what if they were made by something we dotn know
about yet.  What if what looks like two sets of a four legged animal was
actualyl made by a single eight legged animal.  I obviously dont think this
is likely at all, but its the same logic; we cant say anything about it
because we dotn know anything about it, except that there is something that
looks like a footprint.We cant even say its a footprint then can we, we can
only say it looks like one.  f it has the characteristics we expect a foot
print to have, then why is it immpossible to rule outthat there are other
characteristics that would allow us to further refine the classification?
~R

> Regards,
> Randall Irmis
>