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Re: sauropods: homotherm,heterotherm or gigantotherm?



Most creatures that have a large aerobic scope, are
ones that need a large aerobic scope (e.g. dogs and
horses).

And all of them are automatic endotherms... right?

Speaking of horses, they and other critters have
joints that lock while standing, which conserves their
energy.

Relatively hard to imagine for sauropods... they didn't have finished articular surfaces...


Since it involves heat generated, mainly by the
viscera (instead of the muscles), and since it (for
the most part) cannot be turned off; it warrants the
term: automatic endothermy.

I see.

OK, but this limits the _eating_ speed of
poikilothermic animals, doesn't
it? (I mean that you can't eat faster than your
digestion can keep up.) I
wouldn't recommend such a limit to a growing
sauropod...

Why? Since when were sauropods living in zones temperate enough for this to even become an issue?

Some Australian sauropods might have... but anyway, some adult and of course all sufficiently young sauropods were small enough for day-night fluctuations to be potentially important.


What do you mean? That coprolite contains plenty of
bone fragments that don't occur in crocodile droppings.

True, but they do occur in ora droppings. Besides that, the point is that this particular _Tyrannosaurus_, didn't pick the meat off the bones like most mammalian and avian predators do.

Isn't there a partial *Triceratops* skeleton where beautiful scratch marks show a tyrannosaurid was trying to get the meat off the vertebrae? (Was in Scientific American.) Besides, *Tyrannosaurus* was well equipped to chew bones. Oras have been said to swallow clean bones whole. Apparently tyrannosaurs are more similar to hyenas in this respect...


Just a quick mention here. _Quinkana_ seems to have
spawned at least one individual that hit the 1-2 tonne
mark.

Although the skull shape suggests mekosuchines fed more on terrestrial (or at least large) prey than is common among other crocodiles, there's AFAIK no evidence that they actually were terrestrial...


Maybe we'll luck out, and these landlubbing crocs will
be one of the next features in Indiana University
Press's "Life of the Past" series.

Maybe they'll do one on Ziphosuchia and Gobiosuchidae one day... here's waiting for a description of the well-known postcrania of *Baurusuchus* and *Uberabasuchus*...


Said birdies are just too small (and to little
insulated) to keep a constant body
temperature, so they rely on their parents instead.

I don't know. That seems like a poor excuse. Yeah those birds are tiny, but mice are that size, or smaller. Yet they still retain an automatic endotherm lifestyle. Well, much of the time anyway.

Adult mice are well insulated. In fact, the tail is not insulated so it can be used to get rid of excess heat when necessary.


Though now I'm wondering if baby mice
are ectothermic too.

Baby mammals of that kind of size are considered ectothermic in all of the few places in the literature that I've seen mentioning them. Like altricial baby birds, they are not insulated...


> It would appear that food availability, and
> nutrient partitioning (rather than general metabolic
> rate) are the prime factors in fast growth.

Yeah... and body temperature.

Which can be kept elevated through more ways than just using a souped up metabolism.

But once you are tachymetabolic, for whatever reason, and have a surface-to-volume ratio and/or insulation that makes it possible, you get a +- constant high body temperature as a side effect...