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Re: Yet more reptile stuff (long)
In a message dated 12/18/98 12:38:33 PM Eastern Standard Time, email@example.com
essence, I've changed my argument on you: I recognize the utility of
grouping turtles, squamates, and archosaurs together, but dislike the
use of "reptilia" as a label for that grouping, mostly due to the fact
that it doesn't mean the same thing to most folks as it does to you. >>
Perhaps you should stick with your original argument.
If reptiles are defined as something like cold-blooded egg-layers with scales
then you have a perfectly workable definition. Dinosaurs and birds disappear
from your grouping, but then so did mammals under any definition. Do you
really want to keep birds as reptiles?
The common descent element becomes less of a hindrance if the groupings are in
fact 'arbitrary'. Definitions become based not on 'historical' connections,
but on description. Of course, your definition is equally arbitrary, but is
splitting so bad if based on those obvious aspects you've been talking about?
Once beyond the broad groups, the technical discussions are about more or less
contemporary groups with much more elaborate descriptive definitions. The
ability to define related groups over time then becomes based on an observed
continuing series of linked changes in physical characteristics, which is a
very familiar mechanism.
In short, take the chance to define the 'super group' you've been offered.
Let ornithodirans go in peace! (Or, pace Bakker, at least Dinosauria.)