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Date: Wed, 16 Jun 2004 22:20:59 +0200
From: David Marjanovic <david.marjanovic@gmx.at>
To: DML <dinosaur@usc.edu>, PML <phylocode@ouvaxa.cats.ohiou.edu>
Subject: Re: First International Phylogenetic Nomenclature Meeting
----- Original Message ----- From: "Mickey Mortimer" <Mickey_Mortimer111@msn.com> Sent: Wednesday, June 16, 2004 4:45 AM > > > Diapsida Osborn 1903 = Apomorphy (1st reptile with > > > Caiman crocodilus' two temporal arches/fenestra). > > > > That name _really_ cries for an apomorphy-based definition. > > The apomorphy is very unambiguous (unlike "powered flight" > > or "feathers"), and fossils around the base of Diapsida often > > include skulls, so I don't see a serious problem here. > > M[ü]ller (2003) suggests the lower temporal arch of some saurians > (rhynchocephalians, turtles, placodonts, choristoderes, > rhynchosaurs+archosauriformes, trilophosaurs) is not homologous with that of > basal diapsids like Petrolacosaurus and Youngina. If this is true, only the > Archosauriformes + Rhynchosauria node would be Diapsida according to > Gauthier et al.'s definition, the lower arch in other clades being > convergent. > M[ü]ller, J., 2003, Early loss and multiple return of the lower temporal > arcade in diapsid reptiles: Naturwissenschaften, v. 90, p. 473-476. Well. The lower temporal arch of (Archosauriformes + Rhynchosauria) is not homologous with those of the basalmost diapsids. The fenestrae are, though, even though the lower one was open for a long part of Permian diapsid history (and still is in over 1/3 of living diapsids) due to the absence of the arch ventral to the fenestra. The lower temporal arch is also absent in the new arboreal clade and *Claudiosaurus*, outside the crown-group. > > > Rhynchocephalia Guenther 1867 = Apomorphy (1st lepidosaur with Sphenodon > > > punctatus' premaxillary chisels). > > > > Probably similarly unambiguous. I just hope we can use *Sphenodontida* or > > suchlike for the stem. :-) > > I'm guessing they are derived from fused teeth, right? Somewhere, a taxon > existed with slightly fused teeth, resembling Sphenodon's morphology > somewhat. We'll just need to keep altering the definition if we keep it > apomorphy-based. Not if the "premaxillary chisels" are sufficiently described & illustrated. > > > As does Sereno (gasp!)- > > > Archosauria: Crown Clade (Crocodylus niloticus and Passer domesticus) > > > > Fine, fine. But using a nonavian dinosaur would have been even better > > (Rec. 11A). > > Just what was Archosauria first designed to encompass? In any case it was designed to be a reptilian subclass or superorder, and thus to paraphyletically exclude birds. Following Rec. 11A Example 1, this means that no internal specifier should be a bird. > > Oh, they aren't even the problem. If he's right, then *Pterosauria* _does > > not exist_. Why? Because *Pterosauromorpha* is defined as a part of > > *Archosauria* -- and at least *Longisquama* is most likely not an > > archosaur. > > So according to Phylocode, if you start a definition by saying "members of > clade x that are...", and if the clade you define isn't a member of clade x, > then the taxon is invalid? This is not regulated. In this case, I applied logic. If pterosaurs are not archosaurs, then there are no archosaurs that are closer to *Pterosauria* than to *Dinosauria*, which means that *Pterosauromorpha* self-destructs. And *Pterosauria* is defined as a part of *Pterosauromorpha*; if the latter doesn't exist, the former can't exist either.