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Re: Ceratosauria vs. Neotheropoda?

These two names are indeed heterodefinitional synonyms under current
phylogenies, in which ceratosaurids are more closely related to
tetanurans than to coelophysids.  If the Phylocode had been
implemented, and these two definitions were governed by it, then we
would indeed have to treat Ceratosauria as the senior synonym.

However, as the code has NOT yet been implemented, strict priority
does not pertain, and we still have freedom to choose on other
criteria.  In this case, it obvious that the current content of the
name Ceratosauria (as defined by Rowe and Gauthier) does not
correspond with what those authors intended when they defined that
name, and so according to the recommendations of *ahem* Taylor (2007),
it's best to set that name aside (or, better, give it a new and better
definition as something like (Ceratosaurus not Tyrannosaurus)).

We hope that by the time the Phylocode IS implemented, the world will
have had enough experience of phylogenetic nomenclature that
mis-definitions like this one of Ceratosauria will be much rarer than
they were back in the Manifest Destiny days.

2009/11/20 Augusto Haro <augustoharo@gmail.com>:
> Question for people who know about Phylocode:
> Langer et al. (2009) pointed out that the oldest available
> phylogenetic definition of Ceratosauria is synonymous with
> Neotheropoda. They point out that Rowe and Gauthier (1990) defined
> Ceratosauria as a node-based taxon this way: "We employ the name
> Ceratosauria for the group including Ceratosaurus nasicornis,
> Dilophosaurus wetherilli, Liliensternus liliensterni, Coelophysis
> bauri, Syntarsus rhodesiensis, Syntarsus kayentakatae, Segisaurus
> halli, Sarcosaurus woodi , and all other taxa stemming from their most
> recent common ancestor".
> Sereno (1998) defined Neotheropoda this way: "Coelophysis, Neornithes,
> their most recent common ancestor and all descendants", and later
> (2005), this way: "The least inclusive clade containing Coelophysis
> bauri (Cope 1889) and Passer domesticus (Linnaeus 1758)."
> Accepting the phylogenetic hypothesis of Rauhut (2003), that what
> Gauthier called Ceratosauria is not monophyletic, with Ceratosaurus
> being closer to Tetanurae than to Coelophysis, it seems that both
> definitions group the same taxa, as expressed in Langer et al (2009).
> Is there a reason for not using Ceratosauria instead of Neotheropoda?
> The definition by Rowe and Gauthier (1990) seems like acceptably
> constructed from the comments.