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Re: Battat's hair; Prototheria



>>Monotreme mommas make milk--how can they
>>not be mammals?
>
>   As I understand it, they (spiny anteaters, echindas, and platypuses) don't
>have a special gland in one spot on their bodies such as a mammary gland, but
>rather they "sweat" a milk-like equivalent out of tiny gland spread all over
>their bodies like pores (which the babies lap up rather than nurse).
>   No breasts=not a mammal
>   Now how would you prove therapsids did it one way or another?
>
>Betty Cunningham(Flyinggoat@aol.com)

Not quite right. Both Echidnas and Platypus have milk secreteing glands
which are localised in patched of the belly, protobreasts if you like. And
I wouldn't hange the whole definition of mammals on one character, breasts
alone do not maketh a mammal. In fact few mammals have 'breasts'; all have
nipples, something the monotremes lack, all have milk secreteing glands,
something monotremes have, but it is only in humans, lactating dugongs and
a few other mammals that the milk glands form a true breast.

Monotremes do have mandibles composed soley of the dentary with the
articular and quadrate completely shifted into the ear region. While they
lay eggs, retain a septomaxilla and lack nipples, they are more mammal than
reptile (endothermic, furry and milk producing).

Further to this string, someone quoted Mike Archer earlier saying that he
said monotremes were therapsids. I was talking to Mike about this and he
only meant it, somewhat tongue-in-cheek, in the broadest cladistic terms:
yes monotremes are therapsids, but aren't all mammals?

Cheers, Paul

pwillis@ozemail.com.au

"Nature conceals her mysteries, not by her cunning, but by her essential
grandeur"
                                Albert Einstein