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Re: Study: Platypus Retains Bird Sex Link

Hi Dora,

<<I understand that mammals are descended from a very primitive reptile near
the foot of the reptile family tree.    Dinosaurs are very highly evolved
reptiles near the top fo the reptile family tree...>>

Mammals are (and are descendants of) synapsids.  While such critters used to
be termed "mammal-like reptiles", they're now usually seen as distinct.  We
seem to be sister-lines of things called amniotes.  Synapsids may pre-date
reptiles by a bit.  Our skin is positively 'primitive' and more
amphibian-like.  It's full of antique glands rather than complex, strong
keratin scales.

However, that just means our synapsid ancestors were around a long time ago.
We're highly derived synapsids.

Mesozoic Eucynodonts
The Mesozoic - much more than just the dinosaur