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Re: warm-bloodedness





Tim,
Well, at least you can be happy that I recognize two separate dinosaur orders. And neither of them have as many families as the bird Order Passeriformes. I'm not the one who named all those bird families. In terms of species diversity, birds are in the same ballpark as all the reptiles put together.
However, comparing an ostrich, a hummingbird, a penguin, and an owl-----most people would perceive more diversity there than between four divergent dinosaur types. And turtles and crocs are even more uniform (comparatively speaking). But none of them (not even birds) can compete with mammals in the diversity of size and form. Forgive me for saying this, but I can't resist: "Mammals are in a Class of their own." And rightly so, for various reasons, even without including their reptilian ancestors (pelycosaurs and therapsids). Too bad birds don't have something as distinctive as the three ear ossicles. Warm-bloodedness on the other hand, evolved more gradually, and has NOTHING to do with my preference for birds and mammals being recognized as separate classes.
All in all, the three traditional Classes of amniotes are very nicely balanced, and that is why they have been recognized as such for centuries. I see no good reason to change that, especially once I found an alternate way to encode cladistic sister-group information.
-----Ken Kinman
******************************************************
From: "Timothy Williams" <twilliams_alpha@hotmail.com>
Reply-To: twilliams_alpha@hotmail.com
To: kinman@hotmail.com, dinosaur@usc.edu
Subject: Re: warm-bloodedness
Date: Wed, 21 Jun 2000 22:06:38 EDT

Ken Kinman wrote:

    The crocs and turtles and rest of the "reptiles" didn't diversify
anywhere near the extent that birds and mammals did, so they have never
been
seen as candidates for elevation to class status.

I don't see why or how you would consider the "phenetic" difference between
a sparrow and an ostrich to be greater than that between _Tyrannosaurus_ and
_Diplodocus_. Yet, under Linnaean (and Kinman-ian) taxonomy, there are a
multitude of bird "orders", yet the array of theropods and sauropods all get
funneled into a single order, the Saurischia (or Saurischiformes).


It sure doesn't make any sense to me.


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