Ectothermy?

["Larry Febo" <larryf@capital.net>]

* As "twilliams" expressed in a previous post,the condition of endothermy
seems to exist as a sliding scale, and I couldn`t agree more!:
*
* To: dinosaur@usc.edu
* Subject: Endothermy vs Ectothermy (was Re: dermal structures)
* From: twilliams@canr1.cag.uconn.edu
* Date: Tue, 7 Jul 1998 17:30:03 -0500
* Reply-To: twilliams@canr1.cag.uconn.edu
* Sender: owner-dinosaur@usc.edu

> me:
> (<< Just read Tom Hopp`s mention of "one time" evolution of dermal scutes,
> follicles etc., I myself have a strong feeling about a once only
development
> of warm-bloodedness, and that being mainly for the incubation of the young
in
> a colder enviorn. In fact, I`m looking at endothermy before the synapsid-
> diapsid split. (I don`t believe we should place diapsid beginnings way
after
> synapsid development based upon the scant fossil record of early diapsid
> forms).>>)

twilliams:
(I've never thought of endothermy as an all-or-nothing condition, but
as one end of a physiological spectrum.  The ectothermy exhibited by modern
reptiles is at one end of the spectrum, mammalian and avian
endothermy at the other end.  Among modern endotherms I believe it
is the case that certain mammals are _more_ endothermic than others.  )

me again:
I agree!

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.
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!
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!