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RE: Sereno's (2005) new definitions

I'd like to thank Mickey for providing these definitions, and for his comments. I found them hugely interesting and helpful. I think Sereno did a great job overall.

My 2c...

Neotetanurae
(Sinraptor dongi + Carcharodontosaurus saharicus + Allosaurus fragilis + Passer domesticus)
This differs from the original definition (Sereno, 1998) by adding Sinraptor and Carcharodontosaurus as internal specifiers. I suppose it would preserve content better if sinraptorids or carcharodontosaurids end up just basal to carnosaurs + coelurosaurs (Paul, 1988; Coria and Salgado, 1995; Longrich, 2001; Paul, 2002). However, if carcharodontosaurids are ceratosaurs (Bonaparte et al., 1990) or sinraptorids are megalosauroids (Kurzanov, 1989), the original intent of Neotetanurae would be lost.

Not only that, but given that Tetanurae is now re-defined to exclude _Ceratosaurus_ and _Carnotaurus_, having carcharodontosaurids as ceratosaurs would produce a Neotetanurae that is *more* inclusive than Tetanurae. Thus, Tetanurae would be a clade within Neotetanurae. Ass backwards, to say the least.

Coelurosauria
(Passer domesticus <- Allosaurus fragilis, Sinraptor dongi, Carcharodontosaurus saharicus)
One thing I object to is the use of Passer as an internal specifier for Coelurosauria, as birds were not originally classified as coelurosaurs in Huene, 1914 or by anyone until the 1970's at least. Huene included what would today be called coelophysids, coelurids, compsognathids, Ornitholestes and ornithomimids. The best internal specifier for Coelurosauria in my opinion is Ornithomimus. It's always been a coelurosaur,

I had thought Ornithomimosauria was originally erected (by Barsbold, 1976) to be a separate group from Coelurosauria. Thus, _Ornithomimus_ would not have been a coelurosaur when Ornithomimosauria was proposed. Why not use the eponymous genus _Coelurus_ as the internal specifier for Coelurosauria? Surely _Coelurus_ has always been considered a coelurosaur... hasn't it?

Thus I would suggest (Ornithomimus velox <- Allosaurus fragilis, Carcharodontosaurus saharicus) as a definition for Coelurosauria.

I would suggest (Coelurus fragilis <- Allosaurus fragilis, Carcharodontosaurus saharicus) as a definition for Coelurosauria.

Tyrannosauroidea
(Tyrannosaurus rex <- Ornithomimus edmontonicus, Troodon formosus, Velociraptor mongoliensis)

I would have liked to call this clade 'Tyrannosauria' - but that's just my personal opinion. I have a dislike for clades ending in -oidea, given that (as coordinated family-level taxa) they have Linnaean baggage. Same with clades ending as -inae and -ini. Family-level taxa (ending in -idae) are too entrenched, I think, to be discarded.

Alvarezsauridae
I suggest (Alvarezsaurus calvoi <- Ornithomimus velox, Therizinosaurus cheloniformis, Oviraptor philoceratops, Troodon formosus, Passer domesticus) as a first order redefinition of Alvarezsauridae.

I agree. For family-level taxa, the internal specifier should probably always be eponymous. Again, Alvarezsauria might have been a better name for this clade (just my personal opinion).

Therizinosauria
(Therizinosaurus cheloniformis <- Tyrannosaurus rex, Ornithomimus edmontonicus, Shuvuuia deserti, Oviraptor philoceratops, Troodon formosus)
[snip]
If anything, I might suggest using Plateosaurus and Stegosaurus as additional specifiers instead, just to ensure views like Paul's (1984, 1988), Sereno's (1992) and Olshevsky's are covered.

Paul's and Sereno's papers are quite old, and written before the discovery of _Beipiaosaurus_, which seems to cement the therizinosaurs among the higher theropods. I think the therizinosaurs-as-sauropodomorphs or therizinosaurs-as-basal-phytodinosaurs classifications are of little more than historical interest. Olshevsky's current views are unpublished, AFAIK, but any definition probably should not have to accommodate his revolutionary ideas on dinosaur evolution. This is not a criticism of George Olshevsky - but his "Birds-Came-First" theory is so heterodox that it would stretch *any* phylogenetic definition to breaking point.

Troodontidae
(Troodon formosus <- Ornithomimus edmontonicus, Velociraptor mongoliensis, Passer domesticus)

One fly in the ointment.... _Troodon formosus_ may one day be declared a nomen dubium, given that it has isolated teeth as its type material. Maybe _Stenonychosaurus_ or _Saurornithoides_ should be used as an internal specifier instead of _Troodon_. Come to think of it, perhaps the family Troodontidae should be replaced by Saurornithoididae, and ICZN rules on priority be damned! :-) Hey, Parvicursoridae was trumped by the later Mononykidae, so why not replace Troodontidae with Saurornithoididae?

Deinonychosauria
(Troodon formosus + Velociraptor mongoliensis, - Ornithomimus edmontonicus, Passer domesticus)
There have been two basic suggested definitions for Deinonychosauria, one stem-based (Deinonychus <- Passer) by Padian (1997) and the other node based (Troodon + dromaeosaurids) by Sereno (1997). This is a modification of the latter, but explicitly excludes birds and ornithomimosaurs. I prefer Padian's definition because it is based on the eponymous genus, and Colbert and Russell (1969) did not originally specify the inclusion of troodontids. They only include dromaeosaurids in the taxon, and only mention Dromaeosaurus, Deinonychus and Velociraptor as >members of that family.

The only potential problem with Sereno's definition of Deinonychosauria is that what happens if _Microraptor_ is basal to the Troodontidae+Dromaeosauridae clade? With a node-based clade anchored in _Troodon_ and _Velociraptor_, microraptorans would no longer be deinonychosaurs. This is not a deal-breaker, but it does go against the grain of the traditional usage of Deinonychosauria. Maybe _Microraptor_ should be added as a third internal specifier.

Caenagnathoidea
(Chirostenotes pergracilis + Oviraptor philoceratops) This is the same as Maryanska et al.'s (2002) definition, except it replaces Caenagnathus with Chirostenotes. This is a poor decision, as the taxa are not definitely synonymous. 

Agreed.

Unenlagiinae [snip]
Velociraptorinae [snip]
Dromaeosaurinae [snip]

I wonder if it might be better just to discard subfamilies, period. I think Senter has a point in this respect; he deliberately avoided erecting Microraptorinae and opted instead for Microraptoria, because the latter is not under the purview of the ICZN. It's going to be tricky to frame definitions that always have 'subfamily' clades as less inclusive than the 'family' clades AND be assured that a given 'subfamily' does not contain another 'subfamily'.

Confuciusornithidae
(Confuciusornis sanctus <- Passer domesticus)
The only previous definition for this family is that of Chiappe et al. (1999), who used a node-base- (Confuciusornis sanctus + Changchengornis hengdaoziensis). I agree with Sereno that as more members of the confuciusornithid stem are discovered, it would be ideal to be able to refer them to the family. "Proornis" is a relevent example. Another solution would be to use Confuciusornithiformes (Hou et al., 1995) for the stem.

I think Confuciusornithiformes is better as a stem-based definition, with Confuciusornithidae reserved for the less inclusive node-based clade.

One potential pitfall to the above stem-based definition is in the event that we get a topology that shows a clade that includes _Archaeopteryx_ and _Confuciusornis_, but not _Passer_ (or even enantiornithines). In other words, a rump Sauriurae. Should this happen, Confuciusornithidae (or -iformes) would engulf _Archaeopteryx_ as well. Given just how 'froggy' basal avian phylogeny is, I think definitions pertaining to this part of the tree should have many external specifiers. I would use both _Archaeopteryx_ and _Enantiornis_ as external specifiers for a stem-based Confuciusornithidae (or -iformes).

Archaeopterygidae
(Archaeopteryx lithographica <- Passer domesticus)
This is the first published definition of Archaeopterygidae. I would recommend a few additional external specifiers- Dromaeosaurus albertensis (Paul, 1988; 2002), Troodon formosus and Enantiornis leali (Martin, Feduccia, Hou, et al.).

Definitely. But I would also add _Confuciusornis_ as an additional external specifier.

I would have used (Archaeopteryx lithographica <- Passer domesticus) to define Archaeopterygiformes, and have a narrower definition of Archaeopterygidae. Again, just personal preference.

Oviraptoriformes
(Oviraptor philoceratops <- Passer domesticus) At last, a defined replacement for Enigmosauria (so we can stop having those tedious debates on the DML; but Enigmosauria is still listed on >TaxonSearch- I told you people don't like pretending things don't exist). I like this clade and definition, which even work in Maryanska et al. (2002) and Lu et al. (2002) where oviraptorosaurs are ornithurines. 

Caenagnathiformes was already available.  Oh well.

Did Sereno name and define a Paraves+Oviraptoriformes clade? In other words, a clade of maniraptorans that is limied to therizinosaurs, oviraptorosaurs, deinonychosaurs, and birds?

Microraptorinae

I think this clade should be supplanted by Microraptoria. Further, as I said above, I think clades ending in -inae are more trouble than what they are worth, and can be jettisoned in favor of clade names that are not coordinated with family-level taxa. This way, clades can be re-arranged without having to adhere to a Linnaean hierarchy. I think it might be helpful if clades ending in -oidea were discarded too, for the same reason.

Cheers

Tim