Re: CROCODYLOMORPH ENDOTHERMY

["Nicholas J. Pharris" <pharrinj@PLU.edu>]

On Fri, 26 Jan 1996 Dinogeorge@aol.com wrote:

> In a message dated 96-01-25 20:08:54 EST, pharrinj@PLU.edu (Nicholas J.
> Pharris) writes:
> 
> >I'm also not convinced that ectotherms would need or could use "long, 
> >erect limbs and tall bodies," 
> 
> Umm--they could and did use their long, erect limbs, etc. With the increased
> blood aeration provided by the four-chambered heart (no possibility of mixing
> of aerated with stale blood), the early thecodontians were much more active
> animals than their proto-lepidosaur diapsid relatives. By the way, the
> four-chambered heart also made the smaller thecodontians more efficient
> climbers.
> 

Point taken, but I don't believe that an ectothermic physiology could 
support such an active, erect animal.

> Four-chambered heart first, endothermy later. (Note that no extant endotherms
> have three-chambered hearts, but one group of extant ectotherms--crocs--has
> four-chambered hearts.)

A non-problem if crocs are secondarily ectothermic.  Again I repeat my 
query regarding histological studies of fossil crocodiles.

Nick Pharris
Pacific Lutheran University
Tacoma, WA 98447
(206)535-8204
PharriNJ@PLU.edu

"If you can't convince them, confuse them." -- Harry S. Truman