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Re: Are dinosaurs reptiles?



On Fri, 14 Apr 2000, David Krentz wrote:

>   Are dinosaurs reptiles?
>   Yes one of those simple questions that I have a hard time answering without
> boring the heck out of  everyone.  So, I thought I'd leave it up to the
> experts, who have probably answered this question to droves of school children
> in simple language.  The kind of simple language that would be good for a TV
> special aimed at a very general audience.  Sometimes knowing a lot about a
> subject makes the simplest question difficult.  And I thought I'd never need
> that "Handy Answers" book...shame,shame,shame.

Answer: yes

Old System of Classification (Linnaean): Reptilia includes all
land-dwelling vertebrates which lay eggs with shells except for birds
(Aves) and mammals (Mammalia).

New System (cladistic/phylogenetic): Reptilia includes the most recent
common ancestor of turtles, crocodiles, snakes, lizards, and tuataras,
plus all of that ancestor's descendants. Dinosauria is a subset of this
(and Aves a subset of Dinosauria -- hence Aves is part of Reptilia, too).

I think Bakker's Linnaean classification might be the only one that
excluded Dinosauria from Reptilia.

-- T. Michael Keesey .................................. <tmk@dinosauricon.com>
   My Worlds (including The Dinosauricon) ... <http://dinosauricon.com/keesey>
   AOL Instant Messenger ........................................ <Ric Blayze>