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Re: Dino heart--Williston's prediction comes true!



-----Original Message-----
From: Stanley Friesen <sarima@friesen.net>
To: gejd@concentric.net <gejd@concentric.net>
Cc: dinosaur@usc.edu <dinosaur@usc.edu>
Date: Sunday, April 30, 2000 10:41 AM
Subject: Re: Dino heart--Williston's prediction comes true!


(snip)

>However, this does not settle the issue of the ancestral archosaurian
>condition.  The earliest classical archosaurs, the so-called
>"proterosuchians", may also have been aquatic predators, in which case the
>switch-hitting heart may have evolved then. The fully four-chambered heart
>of birds (and presumably dinosaurs) would then have evolved from the
>crocodilian style heart when their ancestors abandoned aquatic hunting.
>

And I thought that the modern crocs ancestors were all terrestrial, "high
walkers", which would lead me to believe that (if anything), the gap between
the crocs ventricles and it`s cold-bloodedness were a secondary development
from a primary four chambered condition. Forgot where I read that (about the
terrestrial nature of early croc ancestors), ...someone please tell me if
I`m wrong here.