Re: Warm-Blooded debate

[Joshua Dyal <j-dyal@geocities.com>]

Jeffrey Martz wrote:

>      If all or most theropods were ectotherms, they would not have had to
> compete with warm blooded predators either.  The point I was trying to
> make is that the ectothermic Komodo dragons are effective at taking down
> supposedly much more active, and frequently very large, endothermic prey.

There are more examples of large ectothermic predators besides Komodo
dragons in mammalian times (i.e. Megalania, and the terrestrial
crocodiles) but they seem to have been incredibly rare, and not able to
compete head to head with endothermic predators for long.  The point
isn't that ectothermic predators can't kill endothermic prey, but that
they can't compete with with endothermic predators for the prey.

>       As far as sprawling being linked to ectothermy and vertical gait
> being linked to endothemy, I find it interesing that no one (as far as I
> know) has suggested upright stance may actually be linked to bipedality.
> It may be more convenient to have the legs positioned underneath the body
> if you are only going to support your weight on two legs.  Yes, I am aware
> of the "Jesus Christ" lizard, as well as many other lizards that can run
> around with sprawled back legs, but early dinosaurs may have had more to
> worry about stance-wise since they were relatively large (by lizard
> standards) animals.  Yes, I am also aware that quadrapedal dinosaurs had
> had at least vertical limbs, but this may have been a feature inherited
> from upright posture/bipedal ancestral dinosaurs, and may have allowed
> them thier large size (the "pillars" of sauropod legs for example).
> Upright posture may be more closely liked to bipedality &/or relatively
> large size then to endothermy.  Any comments?
> 
> LN Jeff
> O-

Wasn't the upright posture developed (at least partially) by
"thecondians" before bipedality?

-- 
Joshua Dyal
j-dyal@geocities.com
http://www.geocities.com/TimesSquare/Arcade/1958/