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Re: 1st Inland sea incursion



Truett,

    Regarding the possible presence of Acrocanthosaurus atokensis in the
eastern U.S., you might (if you haven't already) examine Thomas R. Lipka's
(Yes, one of our listers.) interesting paper, The Affinities of The
Enigmatic Theropods of The Arundel Clay Facies (Aptian), Potomac Formation,
Atlantic Coastal Plain of Maryland, as published in Lower and Middle
Cretaceous Terrestrial Ecosystems, New Mexico Museum of Natural History and
Science Bulletin No. 14, pages 229 through 234.

    Beginning on page 231 of the referenced paper, under the heading of
ARUNDEL ACROCANTHOSAURUS, Lipka discusses reasonable evidence that
Acrocanthosaurus teeth may have been found in Maryland's Arundel Clay Facies
(Aptian).

    Of course it seems impossible from footprints, alone,  to be certain of
a track-maker's  species.  Yet it might be worth mentioning: an as-yet
unpublished theropod footprint (left toe missing) from the Potomac Formation
of Maryland [that , if complete, would possibly be even slightly larger than
the average theropod footprint from the Paluxy River bed in Texas, often
attributed to Acrocanthosaurus], is certainly adequate in size and shape as
to justify reasonable consideration that it MIGHT have been produced by
Acrocanthosaurus (especially in view of the Acrocanthosaurus teeth discussed
by Lipka).  This seems not unreasonable IN THE ABSENCE OF either skeletal or
dental elements that suggest any other EQUALLY LARGE theropod lived in
Maryland at the time.

    The big Maryland theropod track incorporates not only joint-pad
impressions, but what seem to be distinctive, hexagonally and
sub-hexagonally interfaced 'fleshy' (i.e., protruding) dermal-unit
impressions.

    It is conceivable that the Maryland finds (teeth and track) may develop
into one of those situations (described by Martin Lockley in several
publications) wherein paleontology and paleo-ichnology can, cooperatively,
provide a bit more insight than either discipline, alone, might allow in a
given circumstance.

    Hope this helps, Truett.

    Ray Sanford









-----Original Message-----
From: TRUETT GARNER <DINOBOY@worldnet.att.net>
To: dinosaur@usc.edu <dinosaur@usc.edu>
Date: Saturday, January 02, 1999 3:02 AM
Subject: 1st Inland sea incursion


>During what age did N.America first experience an incursion by a sea and
>from which direction ?I'm trying to determine possible faunal exchanges
>between western and eastern N. America . I'm especially concerned with
>whether or not A.atokensis could have inhabited the Southeastern United
>States . I understand that depositional characteristics east of the
>Appalachians mitigate against finding much in the way of complete skeletons
>, but this beast was large enough to at least leave some fragmentary
>remains . Thanks in advance !
>Regards ,
>Truett Garner