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Re: [Re: [Re: Insulation does not = "Warm-blooded"]]
> I'd think so; at least all extant examples seem to appear that way. Course
> it would help if we had a few extant elephant sized reptiles around to
> compare this with.
David Marjanovic wrote:
> Elephants are not gigantothermic, and terrestrial elephant-sized
> (meaning "animals that Linnaeus would classify as reptiles if he'd see
> alive") are probably impossible. See my next post...
Really? I was under the impression that surface area to volume was the
determinant of gigantothermy. I suppose I'll wait for this next post,
though, before I ask for clarification...which just arrived in my inbox,
> > To clarify my original post, I am saying that we have living
> > bradymetabolic and even poikilothermic animals that have insulation.
Bumblebees and hummingbirds, among other examples.
> I know of no good heat trapping comparison studies on these two.
> I wonder if anyone has even bothered with that one yet?
Well, using the Heinrich data that I wrote to you about (from _Bumblebee
Economics_), we see that the insulation on bumblebees increases body
temperature by 65-75%. All you need are the numbers of mammal body
temperatures with or without hair for a very rough comparison.
> these sharks and that turtle have the kind
> of fat one would expect to find in whales and seals (especially the
> turtle), hence, why they are so intriguing to the question at hand.
Boy, that last statement is juicy...I can't quite articulate the point I'm
trying to make from it yet yet...
> Is it now? Sounds a lot like the feathered _Velociraptor_ subjects;
> absence of evidence and all. In fact, isn't this the same type of argument
> that listmember blasted Ruben et al for when it came to turbinates (i.e.
> no living ectotherm has'em, all [most] endotherms have them, dinosaurs and
> early birds didn't have'em therefore they were bradymetabolic).
Thanks for catching me on that. It was really easy to make that statement,
which gives me newfound view of how easy it is for other people to make
this same mistake. I was incorrect, that is nonevidence, and I recant what
I said. As always, "absence of evidence is not evidence of absence."
> Besides, I already mentioned the arthropods, which are terrestrial,
> bradymetabolic poikilotherms, though I'm sure you were hoping for
> something that was at least within vertebrata, in which case, I'll see
> what I can do.
I'm not hoping for a vertebrate, I'm hoping for something the size of your
average enantiornithine or small coelurosaur. Plus, even if you give me an
insect that big, there are serious differences between respiratory and
> Well I say just the opposite, that insulation had its benefits prior to
> leaky cell endothermy and I even have living examples to back it up.
Those which we are discussing...
> I don't see is any living examples of an animal that has leaky cell
> endothermy and no insulation to hold it.
Now its my turn: "absence of evidence is not evidence of absence."
Especially for organisms that may have existed in the past compared to
> Forever the thorn in my side eh? :)
If by "thorn" you mean, "someone who has learned very much from you and is
trying to glean as much knowledge as possible, including debating skills,"
then yes! :)
> Oh and for the record, it is bradymetabolism that I am arguing for. I'm
> pretty sure most, if not all, dinosaurs were homeothermic and even
> endothermic. Whether or not they achieved it through thermoregulatory
> means, gigantothermy or leaky cells as well remains to be seen (probably
> the wrong choice of words there considering the subjects at hand).
I'm not sure I totally disagree with you. I think my biggest issue (at the
moment) is the generalization of all non-avian dinosaurs and
enantiornithines into bradymetabolism.
Can you clarify then, for me? Does bradymetabolism imply ectothermy in
animals larger than hummingbirds? Does bradymetabolism imply low rates of
activity, stereotypically "reptilian" activity levels (notice I said
"stereotypically")? What are the repercussions of your argument on other
aspects of dinosaurian physiology?