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Re: Paralititan (mangrove swamps)



Ken Kinman wrote:

> 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

Ken,
If they occasionally walked into the ecosystem, then they are part of the
ecosystem.  Careful about calling it a swamp, though.  These are generally
pretty sandy systems.  Even the muds tend to be interfingered with sands.  We
are not trying to envision an _Apatasaurus_ up to it shoulders in reeds picture
here.  The water depths were VERY shallow.  Either way, we don't think a lot of
"getting stuck" was going on .

If the predators chased animals into the mangrove forest, then we are talking
about them moving potentially hundreds of meters out into the mangle/channel
areas.  If this is a strategy, then the animals are part of the ecosystem, even
if they spend some of their time in "upland" areas.  However, taking the modern
analog to the extreme, we can postulate that the shore gradient was very
shallow in Baharîya as it is in the modern mangroves that I am familiar with
(Florida and Puerto Rico), then the Baharîya coastline wouldn't have changed
much until probably a dozen or more kilometers from the intertidal area.  It is
much easier to envision this putative ecosystem, I think, if you are familiar
with these sorts of environments in the modern realm.  Inland from the coast, I
suspect we would have moved into a more traditional coastal forest.  However,
regardless of how much time these beasts spent "inland" versus in the Baharîya
mangroves, I think it is extremely interesting that something was drawing them
there.  I could care less if any given individual went to the actual mangles
once in a year, I still think it is bloody cool.

Another interesting point that I think relates to some other posts: we are not
seeing much in the way of storm deposits in the Baharîya.  Indeed, Ken has been
hard pressed to find anything of any high energy at all.  With one possible
exception, none of the quarries that we have excavated appear to be associated
with flood deposits or debris lags from storms.  This is especially true of the
_Parlititan_ type locality.  It looks like business as usual from the
sediments.  It appears as though this bugger was walking along the edge of a
mangle.

-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)