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Re: Brontosauria? Vote for Apatosauria!

David Marjanovic wrote-

Was Megalosauroidea ever formally named as an ICZN taxon, complete with "superfam. nov."?

It doesn't need to be. It was implicitly created when Megalosauridae was. Megalosauroidea was first used by Nopcsa in 1928, but I've never seen that paper.

If *Metriacanthosaurus* really turns out to be a sinraptorid, however... Metriacanthosauridae might qualify as a nomen nudum (I don't have PDW here, nor do I know if that particular work introduced the name), but if not, it certainly has priority.

Can a family name even be a nomen nudum? I can't picture the rules applying (illustration necessary, holotype listed, etc.).

Jay wrote-

Very debatable, isn't it? Spinosauroidea was supposedly used to indicate the phylogenetic
realtionship between Spinosaurids and Torvosaurus, with Spinosauroidea having priority over
Torvosauroidea. Megalosaurus may not unambigously belong to this group. Some exclude it citing
nomina dubia, others include it. If Megalosaurus's position is uncertain in this group, why would
one want the name Megalosauroidea for the group of Torvosaurus + Spinosauridae then to have
Megalosaurus subsequently removed from this group.

It doesn't matter if Megalosaurus is a nomen dubium or not. See Ceratops or Hadrosaurus as examples. As for whether Megalosaurus belongs to the clade, I have yet to see anyone dispute it. Holtz et al. (2004) found it to be a member in their analysis, and Allain (2002) believes so as well. The confusing thing is that Holtz uses and defines Megalosauridae, but then uses and defines Spinosauroidea to contain it. Of course, the issue of multiple Stonesfield Slate large theropods complicates things (Day and Barrett, 2004).

I agree here. Sinraptoridae was clearly proposed for Sinraptor + Yangchuanosaurus.
Metriacanthosaurus isn't as well known wasn't even a purported founding member of this group. The
relationship between Sinraptor + Yangchuanosaurus is quite stable/strong and so warrants a name.
It can't be helped that Metriacanthosaurus's relationship was subsequently revealed. It may not
even be an sinraptorid. Is it an Allosauroid?
But as some believe, if it's related to Sinraptor + Yangchuanosaurus, then perhaps both names
could be preseved. Sinraptoridae for the very stable and strong Sinraptor + Yangchuanosaurus, and
''Metriacanthosauridae'' for the less stable Sinraptoridae + Metriacanthosaurus - of course, this
ignores rank.

Well, Sinraptoridae is already defined as a stem, so if Metriacanthosaurus is closer to Sinraptor than to Allosaurus or Carcharodontosaurus, it's a member. True, it wasn't an original member, but the ICZN doesn't care how long it takes to assign a genus to a family. If that genus has its own older family-level name, the latter gets priority.
Is it an allosauroid? Allain (2002) found it to be one in his analysis, and Rauhut (2003) found it to code identically to Sinraptoridae. It comes out sister to included sinraptorid genera in the latter analysis. Much as with Megalosaurus, though few people have included it in their studies, the ones that have get similar results. Of course, it would be nice if it were restudied in depth. Allain just did so for Erectopus, perhaps he'll get to Metriacanthosaurus next.
Once we start including family names inside other family names, we're spiting the ICZN enough that I don't think we'd care about its family-level priority rule either.

Mickey Mortimer