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Re: Paralititan (mangrove swamps)



Ken Kinman wrote:

> Tracy and Josh,
>       Aren't the soils (muds) of mangrove swamps usually anoxic and
> therefore an unusually ideal area for fossil preservation?
>       If so, couldn't it be a fluke of preservation.  In other words,
> perhaps Paralititan usually lived in other habitats, but only got fossilized
> if one happened to wander into such a swamp and died there.
>       I don't have any firm conviction either one way or the other
> (non-theropods don't interest me much).  Just playing devil's advocate for
> the sake of discussion.
>                         ---Ken

    If it is a fluke of preservation, then it was a reoccurring fluke, because
by far most of the fossils we have produced from Bahariya so far are coming
from the same sorts of environments.  The Bahariya Formation stratigraphicaly
proximal to Stromer's "saurier" beds appears to record the existence of a big
"mangrove coastline" in the Cenomanian, and this is by far one of the most
productive "units" in the Bahariya sequences.
    Bahariya records a very low energy regime.  There doesn't appear to be
enough energy in the system to move around gravel the size of _Paralititan_ (as
our coastal geologist Ken Lacovara loves to term in, but to Lamanna's pain).
Moreover, Ken is convinced that the water depths in the "Bahariya mangroves"
would have been too shallow for the beast to actually float around.  This,
combined with the evidence at the quarry that CGM 81119 was scavenged indicates
that not only this individual, but whatever was munching on it (most likely a
carcharodontosaurid according to my analyses) walked into the mangrove under
their own power.  Did they live there, or were they just walking through?  Who
the hell knows for sure?  However, it is most parsimonious to presume, give the
frequency that we find large vertebrate bones in these sequences, that we have
the record of a fauna that at least didn't hate mangroves, so I would say they
very well might have lived there.  It wasn't just _Paralititan_ that was
running around in this environment, but the theropods in the Bahariya as well,
as far as we can tell.

-Josh

--
Josh Smith
Department of Earth and Environmental Science
University of Pennsylvania
471 Hayden Hall
240 South 33rd Street
Philadelphia, PA  19104-6316
(215) 898-5630 (Office)
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