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Re: Platypus a living fossil?



>From: Tom Holtz <tholtz@geochange.er.usgs.gov>
 > 
 > I have not seen any (paleo- or neontological) systematics work which
 > excludes monotremes from Mammalia.  If you have the ref, I'd be glad to
 > take a look!
 > 

There was a brief period when some plaeontologists considered that
the therian and non-therian mammals originated from seperate subgroups
of the therapsids.

This would have required one of the following:
        1) accept a polyphyletic mammalia (blech)
        2) seperate the non-therians (including the monotremes) from mammalia.
        3) move the lower border of mammalia to include most or all
           of the cynodonts.

Subsequent studies have cast doubt on this conclusion, however, so the
issue has become moot.

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.