What is a reptile? (A?)

Doug.Eernisse at UM.CC.UMICH.EDU Doug.Eernisse at UM.CC.UMICH.EDU
Fri Sep 25 10:55:56 EST 1992


Joe Felsenstein would rather call dinosaurs birds than birds
dinosaurs:
 
> Without attempting to dispute the phylogenetic hypotheses, one could
> point to the principle of priority.  No, birds are not dinosaurs!
> Rather, dinosaurs were birds!  Of course, that won't make the cover of
> Scientific American as easily, but Linnaeus DID describe birds well
> before dinosaurs were known.   So we have to call those big monsters
>-"birds".
> No matter how hard people laugh.
 
But higher taxonomic categories are not bound by the principle of 
priority. Aves is already well diagnosed (i.e., by feathers, for 
example). A revisor does not have to choose the earliest named
subgroup for a group name of higher rank. This issue has been
addressed by Gauthier and others, it is not original with me.
 
Perhaps he also misunderstood my comments:
 
> A bit more seriously, even if it were universally agreed that
> birds and dinosaurs were sister groups, someone could still say that
> dinosaurs were extinct.  It is the closer relationship of birds to
> some groups within dinosaurs than to others that would force
> their inclusion within the dinosaurs ... er ... would force the
> inclusion of the Big Heavy Birds with the other birds.
 
I hope I did not claim that birds and dinosaurs were sister groups.
Rather, I favored the hypothesis that birds and dinosaurs were each
monophyletic lineages, but birds are a subclade of dinosaurs.
Joe is right that relationships of birds within dinosaurs is an
interesting subject as well. I was only trying to address the
competing hypotheses of birds and crocodiles as closest relatives
within archosaurs, vs. birds and other extinct "dinosaur" lineages
as closer relatives than either is to crocodiles. Joe is correct
in that I left out some extinct archosaur lineages (e.g., pterosaurs) 
that are hypothesized to be more proximal archosaurian outgroups 
to dinosaurs than are crocodiles, and thus more relevant to the
issue of the placement of birds within dinosaurs.
 
Doug Eernisse
Museum of Zoology, U. of Michigan
Doug_Ee at um.cc.umich.edu



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