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Re: Paralititan (mangrove swamps)


Josh,
I agree that one likely scenario is that Paralititan and its predator may have been primarily a part of the mangrove ecosystem.
But on the other hand, perhaps they were primarily a part of an ecosystem further inland (lacking anoxic mud that would have preserved them). Perhaps Paralititans occasionally wandered into mangrove swamps (or forced by population pressures?) and sometimes got stuck there and died (and less sticky version of La Brea tar pits??).
Who knows, maybe their predators were even smart enough to learn that if they chased Paralititan towards the swamps, it was an easier way to make a kill. In that case, Paralititan may have hated the swamp, but the predator loved it as a means to an easier meal (whether they actually chased them into the swamp or not).
Just speculating on other possible scenarios that might also fit the facts (but you know a lot more of the details than I do). What type of habitat would one have found inland from these swamps, and would they be far less favorable for fossil preservation?
------Ken
******************************************************** 
From: Josh Smith <smithjb@sas.upenn.edu>
Reply-To: smithjb@sas.upenn.edu
To: kinman@hotmail.com
CC: dinosaur@usc.edu
Subject: Re: Paralititan (mangrove swamps)
Date: Tue, 05 Jun 2001 10:25:45 -0400

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)
(215) 898-0964 (FAX)


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