[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

mammal definition (was "Fossil Discovery Threatens")




Nick,
Don't worry, the vast majority of biologists still recognize the apomorphy-based definition (3 ear ossicles).
The "crown-group" cladistic definition was a dumb idea to begin with, being anchored on the monotremes which have a dismal fossil record. I've even heard cladists distancing themselves from this dubious definition.
------Ken Kinman
******************************************************
From: NJPharris@aol.com
Reply-To: NJPharris@aol.com
To: dinosaur@usc.edu
Subject: Re: Fossil Discovery Threatens Theory of Birds' Evolution
Date: Sun, 25 Jun 2000 04:02:02 EDT

In a message dated 6/25/00 12:05:38 AM Pacific Daylight Time,
dbensen@gotnet.net writes:

> >>The definition of "mammal" has changed in the last decade or so. How do
> you know that a live Olyagopolis would look like a reptile?<<
> Isn't mammals' diagnostic feature (besides mummeries, I mean), their
single
> lower jawbone and the presence of ear bones?


Not according to phylogenetic taxonomists. The "diagnostic feature" for a
mammal, if you're a PT practitioner, is that it is descended from (or is) the
common ancestor of all living mammals.


Personally, I'd prefer the apomorphy-based definition: Mammalia = {the first
ancestor of modern mammals to possess a single lower jawbone + all of its
descendents}; but, alas, it was not to be.


Nick P.
________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com