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RE: Youngest dino remains
Nick is correct. The point is which group is a subset of which other group.
Dinosaurs are not a subset of birds. Bats are a subset of mammals
in the same way the birds are a subset of dinosaurs. The use of "extant"
in the proffered definition ignores the vast number of species that, by
don' happen to be around at this time, but contributed to the evolution
of extant forms.
> From: Pharris Nicholas J[SMTP:firstname.lastname@example.org]
> Sent: Friday, March 19, 1999 5:01 PM
> To: Dinogeorge@aol.com
> Cc: email@example.com; firstname.lastname@example.org
> Subject: Re: Youngest dino remains
> On Fri, 19 Mar 1999 Dinogeorge@aol.com wrote:
> > When I say dinosaurs are birds, I am using the stem
> > group definition of birds as "all archosaurs closer to extant birds than
> > extant crocodiles." This definitin includes the dinosaurs (and in some
> > phylogenies the pterosaurs, too) You can't define bats so as to include
> > mammals this way,
> Sure, I can! I can just use the stem-group definition of bats as "all
> amniotes closer to extant bats than to extant crocodiles." The two are
> precisely equivalent, and they drain the meaning from the terms "bird" and
> "bat" in precisely the same way.
> Nick Pharris
> Pacific Lutheran University
> Tacoma, WA 98447