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Re: sauropods: homotherm,heterotherm or gigantotherm?
Hom[oi]othermy would seem allmost impossible to me. How could an
animal as large as a Seismosaurus have met its food requirements for
one day within that very same day?
I don't see that much of a problem -- except that I can't quantify any of
the following: Firstly there is evidence that many sauropods ate tree
leaves. Including (well... mainly) conifer needles. This plentiful food
resource is today exploited only by insects (and the occasional sloth,
specialized monkey or weird bird), and the sauropods hardly seem to have had
competition in that. Secondly they didn't waste time chewing, at least in
the mouth. Thirdly their heads, while _relatively_ tiny, were still
impressive in absolute dimensions -- commonly on the order of 60 cm long,
sometimes more. And fourthly, make sure you don't overestimate the body
masses of sauropods. Their vertebral columns usually contained more air than
Heterotherm seems like an option,due to the lower food requirements,
What do you mean? Torpor at night? (Bats and hummingbirds are
heterothermic.) Or do you mean a "reptilian" metabolism? (That would be
poikilothermic -- below a certain body mass at least...)
but aren't dinosaurs thought to exhibit homothermy or near-homothermy as a
Do naked mole rats and ,possibly,crocodiles count as
heterotherms descended from homotherms?
Naked mole rats are about half homoiothermic. :-) Quite little research has
been done on Jurassic and Triassic crocodyl...omorphs...
Then I remember there being a theory about sauropods being
gigantotherm,meaning that they maintained their body temperature by means
their size and the warmth that automatically makes them keep,allowing them
to lead active,homotherm lives,without being homotherm themselves and they
would also circumvent the problem of the food requirements,of course. But
do not believe there are analogs for something like that.
There is one known living gigantotherm: the leatherback turtle (*Dermochelys
coriacea*). It has a very compact body shape (pretty much the opposite of a
sauropod -- sauropods even have longer, thinner legs than elephants,
compared to trunk size), quite a bit of insulating fat, and the ingenious
arrangement that its main locomotory muscles -- those that move the
flippers -- are inside the body rather than stretched along the limbs! And
it most assuredly does not lead an active life like what most homoiotherms
do. To get the energy for that, it would need the metabolism of a
homoiothermic animal! (And for that, it would have to eat accordingly.
Means, it would have to be homoiothermic.) Animals are not solar power
plants. A high body temperature is a prerequisite for a fast metabolism, but
it isn't sufficient.
Also,wouldn't it mean that younger or smaller sauropods
(Magyarasaurus for example) had a metabolism they could not rely on?
The proponents of gigantothermy don't seem to have thought about that...
In short,what's the present consensus about sauropod metabolism?
Why are you so sure that there is one at all? :-)