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From: mcginnis@kuhub.cc.ukans.edu
Newsgroups: sci.bio
Subject: Thanks for monotreme replies... one more question.
Message-ID: <1991Apr23.082506.29920@kuhub.cc.ukans.edu>
Date: 23 Apr 91 13:25:06 GMT
Organization: University of Kansas Academic Computing Services
Lines: 30

Thanks for the answers about monotremes.  The summary answer is
that these animals (3 species: duck billed platypus, and the long
and short snouted echidna, spiney ant-eater) have a common cavity
called the urogenital sinus, or cloaca, into which all major internal 
organs that dump stuff outside of the body dump their stuff (urine, 
feces, and sperm).

I haven't heard whether they have a separate uterus... I assume
that they must.

Apparently some other mammals other than monotremes (monotreme means
"one hole" in Latin, I am told) have a urogenital sinus:  armadillo
and sloth for example.

It sounds to me like monotreme is a misnomer and we use it to refer to
oviparous mammals and that all of these animals (plus some others)
happen to have a urogenital sinus.

Sorry if I make misspellings or misuse terms... I'm just a computer nerd
who's curious about this stuff.

Actually, my interest was arroused by an article I read that said that
the little echidna was the only known mammal that does not engage in
REM sleep (a topic that I have been reading about because it is so
similar to a "house cleaning" procedure used in neural network computer
programming... but that's another topic).  And, the echidna, 
coincidentially (?) has the largest (proportionally) prefrontal cortex 
of any mammal.

Interesting stuff.