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

Re: maniraptor taxonomy, etc.




Jeffrey,
As I have said on earlier occasions, exactly where you make the cuts on a continuous tree of life are unavoidably arbitrary to some extent. The exact point where the three ossicles are "fully" developed, we can certainly quibble about, but in my opinion, it is far, far less arbitrary and less destabilizing than anchoring "mammals" on monotremes (whose primitive ancestry is virtually unknown and speculative).
Based on the three ossicles, multituberculates have long been classified as mammals. But whether multituberculates belong to a crown clade Mammalia (anchored on monotremes) is far less certain.
So to answer your question, mammalogists tended to agree more on what constituted a mammal before the cladists started trying to reform it into a cladistic "crown group".
------Ken Kinman
P.S. Got to call it quits for today. My brain is tired, and even my fingers are slowing down. Definitely bedtime.
*******************************************************
From: "Jeffrey Martz" <jeffmartz@earthlink.net>
Reply-To: jeffmartz@earthlink.net
To: <kinman@hotmail.com>, <dinosaur@usc.edu>
Subject: Re: maniraptor taxonomy, etc.
Date: Wed, 19 Jul 2000 21:56:41 -0000



>Yes.  A good idea, but it only solves one small problem.  Call me
>old-fashioned, but I just prefer "characterizing" taxa rather than
>"defining" them.  Both approaches have drawbacks, but I think the >former
is best for the long term.  Mammalia based on the three >auditory ossicles
is far more useful than one anchored on fossil-poor >monotremes (in the
past, present, and the forseeable future).


Why? What happens if when we find a primitive "mammal" or group of
mammals that seems to have three sort of but not quite ear ossicles? Are
they "kind of" mammals? How fully adapted do the bones have to be for
hearing before it becomes a mammal? What happens when you get a fossil form
where the condition of the ear ossicles is debatable? Did taxonomists using
morphological defintions really agree any better about the membership of
groups before phylogenetic taxonomists came along?


LN Jeff

He who stops at being better stops being good.
-Oliver Cromwell

Fear not those who argue but those who dodge.
-Marie von Ebner Eschenbach

Jeffrey W. Martz
3002 4th St. # C26
Lubbock, TX
79415
http://www.homestead.com/illustrations/Illustration
(806) 747-7910

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