Re: Warm-Blooded debate

[brucet@mindspring.com (bruce thompson)]

<snippage>

>> Indications are that adult fully endothermic sauropods would have overheated,
>> particularly since they have no known anatomical structures with which to
>> dump excess body heat, so full adult endothermy >likely< developed in the
>> aforementioned lineage leading to birds >after< the sauropods diverged.
>
>I still wonder about this.  Animals as large as elephants do not
>overheat, and their main source of cooling other than getting in the
>shade is radiation via the ears.  Of course they radiate heat back
>to the environment at night as large animals do as well.  I don't
>know if anyone has looked at the entire skin being a radiator in
>elephants or not (active not passive), but I'll find out and get back
>to you.  If a sauropod can use its circulatory system to radiate
>heat back to the environment via the skin as well, then I see no
>reason for them to overheat.

<snippage>

        Elephants blow dust and water on their backs, presumably to cool
down.  Hard to see how the animals' skin could radiate heat faster than the
sun is pouring it on.
        I haven't heard, in several years, any discussion of how sauropods
dealt with their relatively tiny heads.  Has that conundrum been resolved?
Seems to me that an herbivorous endotherm the size of a C-130 Galaxy
aircraft, but equiped with a horse-sized head, would have to eat at
shrew-like rates to keep warm.  Yet if the thing were ectothermic, wouldn't
that reduce the caloric rate requirements and thus make the tiny head
manageable?

bruce



        "Dammit, Philbert; what kind of a lepidopterist are you?  For god's 
sake,
man; stand up to them!"