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Re: eggshells, therizinosaurs & tyrannosaurs
> I think this has already happened with Ornithosuchia, which >according to
many phylogenies no longer includes Ornithosuchidae >(type genus
>Excellent example. (Wasn't that one also Sereno's?)
No, Ornthosuchia is a stem-based clade (all archosaurs closer to birds
then to crocodilians) established by Gauthier (1986; his Saurischian
monophyly paper, which I unfortunately can't find right now). Gauthier also
named "Ornithodira" as a node based clade within Ornithosuchia, which
included dinosaurs, pterosaurs, and Lagosuchus, but excluded the
Ornithosuchidae and Euparkeria (these were in Ornithosuchia in Gauthier's
analysis). However, since these latter two taxa fall into Pseudosuchia and
in basal Archosauriformes respectively in most later cladistic analyses, the
membership of Ornithodira is now pretty much synonymous with Ornithosuchia
(assuming the pterosaurs belong and nothing is found to be an Ornithosuchian
outside of Ornithodira). I'm not sure what taking pterosaurs away from the
Ornithosuchia would do to Ornithodira. Since both groups were defined in
the same paper, I'm not sure if Ornithodira might not be an equally valid
name (if the pterosaurs stay).
In any case, the Ornithosuchia-Ornithosuchidae "problem" is a purely
asthetic one. The idea of a higher level taxon that is named for
Orntihosuchus and its kin but doesn't include them bugs people, but doesn't
really cause practical difficulty. I know the difference between
Ornithosuchia and Ornithosuchidae. You know the difference between
Ornithosuchia and Ornithosuchidae. Where is the problem?
Same thing with Pseudosuchia and 'Crocodylotarsi'; so what if
crocodiles are included in a clade that translates into "false crocodile"?
If we want to get philosophical, most of the pseudosuchians ARE "false
crocodiles", things that look sort of croc like but aren't.
Aesthetic problems with names is a bogus reason to create new ones that
creates just forces authors to have to write more in the introduction of
thier phylogenetic analyses. The amount of confusion it causes is greater
then the confusion it supposedly fixes by introducing "more appropriate"
He who stops at being better stops being good.
Fear not those who argue but those who dodge.
-Marie von Ebner Eschenbach
Jeffrey W. Martz
3002 4th St. # C26