Re: Message from Ralph Molnar

[Mikiel <Mikiel@ASU.Edu>]

On Thu, 4 May 1995 VanKathy@aol.com wrote:

> Bill Adlam asked me how I thought that the examination of dinosaur DNA would
> lead to confirmation of dinosaurian metabolism.  The most straightforward --
> and probably least sophisticated -- path to determining this (or at least
> adding a very strong argument for this) would be to compare specific DNA
> sequences with that of living animals.  This would identify their closest
> living kin, which in all likelyhood, will be birds -- especially considering
> that the much of the DNA being studied now comes from remains of some of the
> the most avian of dinosaurs.  If the matches are close enough to birds and
> far enough from reptiles this in itself would be a fairly strong argument for
> an active metabolism.

        I don't believe that proof of dinosaur affinity with birds would 
be a valid argument for an "active metabolism" in dinosaurs.  Dinosaurs 
are an amazingly diverse group of animals.  Ornithischian and saurischian 
dinosaurs diverged early on in the evolution of the group, in the Late 
Triassic.  Birds appeared in the Jurassic, and although descended from 
saurischian dinosaurs, have something like 60 million years separation 
from ornithischian dinos.  Even if it could be shown that the latest 
Cretaceous dinosaurs of both kinds had an "active metabolism," it 
wouldn't necessarily follow that _all_ dinosaurs did.  Likewise, even if 
all saurischians had it, it is still possible that not all ornithischians 
did.
        Dinosaurs are too diverse a group to make broad assertions about 
their physiology.

-Mikiel