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Re: New refs (medium)



Scott Hartman (DinoBoyGraphics@aol.com) wrote:

<Environments have a carrying capacity that animal populations cannot
exceed (for long).  If sauropods were low RMR ectotherms, there would
simply be more of them (a point made by R. McNeil Alexander in his book).>

  I do not think this is really very applicable to sauropods. Studies
based on environmental capatities have never taken into account the
enourmous size of sauropods compared to elephants for a given terrestrial
ecosystem. Though the environment can only sustain so much for so long,
elephants and whales have managed to circumvent this by having large
groups and migrating. It is just as applicable for sauropods without, I
daresay, much more extant evidence. The logical inference that an animal
would be better sustained if ectothermic by the environment is one
approach to solving this. I did not say sauropods were ectothermic by this
measure, however, since by their very mass one would implicate them as
perfect examples of gigantothermic supporters. Just being big drives their
thermal biology. At that point, constraints for elephants no longer apply.
They are also, on average, much bigger than any terrestrial mammal to
date, and no one has been able to indicate whether any *Paraceratherium*
was endothermic. It is assumed rather, because its a placental mammal,
depsite variation within placentals (albeit by tiny ones) for
poekilothermy.

<The high fecundity of even the largest dinosaurs (compared to large
mammals) could have allowed them to maintain populations with
> fewer adult animals.>

  How is this supported? I do not think we are aware of how to measure the
death rate, constancy of populations or "herds" or so forth. Every group
of dinosaur the size of an elephant or larger that is also herbivorous
shows gregarious and itinerant behavior in some ways (with the exception
of thyreophores, of which there are very few tracks available and which do
not show any gregarious behavior, and this is true of rhinos as well);
theropod dinosaurs may be assumed to "follow" these are there was volumes
enough to sustain them. The meat needed to sustain a
Judithian/Nemegtian/Lancian tyrannosaur may have provoked it to consume
the greater volume of a carcass' mass every few days. If endothermic.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

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