Re: Nemegtian Tyrannosaurs

[Graydon <oak@uniserve.com>]

MarkSabercat@aol.com wrote:
>In a message dated 5/4/03 11:20 : EDT Dinogeorge wrote:
>>This all seems like explanations piled on explanations and speculation
>>piled on speculation. Maybe this, maybe that. Perhaps this, perhaps
>>that. The most parsimonious explanation would be that T. bataar is a
>>different species than T. efremovi and that both are different genera
>>from T. rex.
>But with all due respect, this isn't really any more of an explanation,
>it simply further begs the question of why there seems to be
>differential mortality or preservation biasis. Granted that the posts
>on this subject have to date been pretty speculative, but we have to
>start with something in order to begin trying out ideas that can later
>be proven or disproven as we get better evidence. I'd like to see some
>input from field biology studies, if they exist, on the differential
>mortality of juvenile among extent, carnivorous bird and mammal
>populations in continental vs. marine dominated climates; we have to be
>careful of undue extrapolation from very different animals, but it
>might help us come up with some reasonable hypotheses.

You don't have to postulate differential mortality rates at all; you
just have to postulate that T. rex was highly territorial and that
juveniles did not necessarily remain with a family group for their
entire life cycle.

I think those are pretty easy assumptions to make about a large
carnivore; even in K-strategist group-hunting carnivores like lions, the
juveniles get kicked out to find their own territory, so it's very easy
to believe in a large theropod.

So the juveniles necessarily wind up in less desirable hunting
territory, and the preservational bias we're seeing is because the T.
rex specimens are coming out of the sort of prime hunting territory
where you'd expect most of the carnivores to be large adults able to
defend that highly desirable territory from other large adults.

Where would the abundant-large-prey region associated with the Nemget
be?  Is it accessible for collection?  If it is, that's where to look
for the big adult T. bataar skeletons.

-- 
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