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Re: warm-bloodedness

On Thu, 22 Jun 2000, philidor11 wrote:

> <The prevalent phylogenetic definition of Aves is "the most recent common
> ancestor of _Archaeopteryx_ and extant birds, plus all of its descendants".
> So, by definition, _Archaeopteryx_ belongs to Aves.>
> Thanks.
> I like that ambiguous 'and'.


> If Archie is on an extinct side branch,

As it's usually thought to be.

> he's still a bird.  That means any number of species not on the direct
> line to extant birds could also be in the group, including possibly
> some without feathers.

I would doubt that. Since Archie and modern birds have pretty much
identical feathers, their most recent common ancestor quite likely did,
too. It isn't impossible that a bird would become completely featherless,
but it is without precedent.

> Any chance TR could be among the gang?

I've never seen Tyrannosauroidea placed there, but Greg Paul did place
Troodontidae, Avimimidae, Ornithomimosauria, Dromaeosauridae, and
Oviraptorosauria within {_Archaeopteryx_ + Neornithes} in _Predatory
Dinosaurs of the World_.

In any case, it is not definitely known that Tyrannosauroidea lacked
feathery integument.

T. Michael Keesey <tmk@dinosauricon.com> | AIM <Ric Blayze> | ICQ <77314901>
                 My Worlds <http://dinosauricon.com/keesey>
                 The Dinosauricon <http://dinosauricon.com>