Re: Ectothermy?

["Thomas R. Holtz, Jr." <th81@umail.umd.edu>]

At 07:57 AM 9/2/98 -0400, Larry Febo wrote:
>* As "twilliams" expressed in a previous post,the condition of endothermy
>seems to exist as a sliding scale, and I couldn`t agree more!:

Actually, many vertebrate physiologists would agree with you.

>So, when I say that the condition evolved only once, I am referring to the
>common view of "warm-bloodedness"( i.e. mammals and birds)as opposed to "
>cold-bloodedness" (i.e. reptilian). Actually what I am indicating would more
>precisely be that excess endothermy needed to actively brood the young in a
>land enviornment.,and even this varies, as in the case of marsupial vs
>mammal.

By "mammal", I presume you mean "placental" (shame, shame on you for such
poor treatment of our pouched cousins! :-)

And let's not forget about brooding pythons, who are (temporary) endothermic.

>Perhaps the term ectothermic is not a usefull one at all, perhaps all
>conditions should be described in terms of the amount of ENDOTHERMY, period!

Ugh!!  No!  The history of terrestrial vertebrate life is more than a bird-
and mammal-generating engine: there are a lot of different ways of being an
ectotherm, just as there are more than one way of being an endotherm.

If anything was gained from the 1970s and 1980s debates on dinosaurian
endothermy, it is the fact that we better understand what terms with which
we are dealing, prior to trying to buttonhole dinosaurs into one or another
particular category.

>Maybe it`s not my place to suggest these sorts of major changes in
>descriptive vocabulary, but it seems it would make  things a bit easier to
>explain, as well as allow for more accurate descriptions. So, all those for
>the extinction of the term Ectothermic...say aye!

Again, nay!

My suggestion here to those interested in the topic: check out studies
thermoregulation in modern animals that *are not* focused dinosaurs (plenty
of references in the appropriate chapters and articles in Currie & Padian's
_Encyc. of Dinos._ and Farlow & Brett-Surman's _The Complete Dino._).  Get a
better idea of what is known among modern forms.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661