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Re: Oh no! Not Monotremes again!



>From: jshields@iol.ie (James Shields)
 > 
 > The interesting bit, however, is this:
 > 
 > "Although they resemble reptiles in that they lay eggs, the monotremes are
 > true mammals. They possess such distinctively mammalian characteristics such
 > as mammary glands, hair, a large brain, and a complete diaphragm."

This is correct.  They should also mention milk glands.
 > 
 > And:
 > 
 > "Most authorities beleive that the order Monotrema originated from a line of
 > mammal-like reptiles different from that which gave rise to the other 
 > mammals."

This is now out of date.  This seemed to be the case for awhile
in the mid '80's, but has now been shown to be based on incorrect
analysis.
 > 
 > No cladistics here!

Actually, the supposed evience for a seperate origin *was* based
on cladistic analysis - it just wasn't transformed into classification
by many people.

But in fact, if it had turned out to be true, even us non-cladistic
evolutionary taxonomists would have had to seperate the monotremes,
and the other non-therian mammals, from Mammalia, on the grounds that
such a Mammalia would have been *poly*phyletic, which *nobody*
accepts as valid, cladist or not.

[The main argument between cladists and non-cladists is the validity
of *para*phyletic taxa].

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

The peace of God be with you.