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Re: AW: Heterodontosaurid with protofeathers

On Tue, Mar 31, 2009 at 9:04 PM, Dora Smith <villandra@austin.rr.com> wrote:
> So, you mean, all reptiles once had fur?

I haven't mentioned a single reptile. I'm saying fur probably arose
within the mammalian stem group.

See the cladogram here: http://en.wikipedia.org/wiki/Mammaliformes#Phylogeny

We have evidence of fur in _Docodonta_ and (of course) in _Mammalia_,
so it probably existed in some common ancestor of those two clades,
but not prior to the sauropsid-synapsid split. In fact, since
_Estemmenosuchus_, a dinocephalian stem-mammal, is supposed to have
been scaly, it may have been after the dinocephalian-neotherapsid
split (see: http://en.wikipedia.org/wiki/Therapsida#Phylogeny).

The actual picture may be more complex, as Dann was saying, but that's
the best assumption for now.
T. Michael Keesey
Technical Consultant and Developer, Internet Technologies
Glendale, California