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Centrosaurs+chasmosaurs (ommitting suffixes for neutrality) are quite obviously a monophyletic clade though. What do you call the clade they comprise? And is Ceratops diagnostic enough to be placed in one of the two subfamilies? It's obviously a member
of the centrosaur+chasmosaur clade, as we have no reason to suspect more basal ceratopsians with horns existed in the locality Ceratops was found in. I think it's pointless to bump up the ranks and buck a century long tradition of using Ceratopsidae consistently
in circumscription.
I feel as if splitting Ceratopsidae into two families wouldn't catch on anyways, because in phylogenetics the names of clades technically don't really matter so much as the composition of the clade itself. The family could be called "78041", and still
be perfectly fine, and it's convenient because Ceratops itself almost certainly belongs in it somewhere (probably in Centrosaurinae, I would argue). Ceratops is complete junk for a phylogenetic analysis but it's clearly Ceratopsidae incertae sedis. I guess
I just believe in keeping things the way people are used to, although I must admit there's a sense of tidiness gleaned from casting nomina dubia into the abyss.
Thomas Yazbeck
From: dinosaur-l-request@mymaillists.usc.edu <dinosaur-l-request@mymaillists.usc.edu> on behalf of Tim Williams <tijawi@gmail.com>
Sent: Sunday, November 22, 2020 12:52 AM To: dinosaur-l@usc.edu <dinosaur-l@usc.edu> Subject: Re: [dinosaur] Do people still use Troodon? I don't think it's sensible to have families named after nomina dubia.
So from that perspective, Troodontidae should be called Saurornithoididae. I also think it would be practical to discard Ceratopsidae and split it up into two families, Centrosauridae and Chasmosauridae. The reason why families should NOT be named after indeterminate genera is because a family must include the name-giving genus (which makes sense). So Ceratopsidae must include _Ceratops_. But if _Ceratops_ is a nomen dubium, it should not be treated as a taxon, and it should not be used as an OTU in a phylogenetic analysis. There is/was no creature called _Ceratops_; it's just a name. Genus _Ceratops_ is a zombie: it's a dead name that's kept alive purely for bookkeeping reasons, simply because it gives its name to Ceratopsidae. I know the ICZN allows this sort of thing, but from a biological standpoint it's antiquated and bizarre. On Sat, Nov 21, 2020 at 4:48 PM Ethan Schoales <ethan.schoales@gmail.com> wrote: > > > Isn't Ceratops already obsolete? It's technically the type genus of Ceratopsidae, but it might as well not be. > > On Sat, Nov 21, 2020 at 12:46 AM Tim Williams <tijawi@gmail.com> wrote: >> >> Ethan Schoales <ethan.schoales@gmail.com> wrote: >> >> > I've seen some recent papers on the DML that use it as valid, but Zanno et al. 2017 declared it dubious due to its non-diagnostic holotype. Basically, what people worried would happen to Diplodocus, hence the petition. >> >> Yes. Hence the petition, :-Z >> >> > I wonder if, in a few decades, if not sooner, Troodon will be where Trachodon is now - a name you only see in old books >> > >> > But I think that declaring that we can no longer use a name that's been widely used for over 150 years is a bad idea. >> >> While it's true that the name _Troodon_ has been around since 1856, >> it's had a very tortuous taxonomic history. For a while (~1924-1945) >> _Troodon_ was considered a pachycephalosaur., before being recognized >> (again) as some kind of theropod. It was only in 1987 that _Troodon_ >> was recognized as belonging to the same family as the better known >> _Stenonychosaurus_ and _Saurornithoides_, and the family was therefore >> given the name Troodontidae. (I prefer Saurornithoididae, but I'm >> fighting a losing battle on that front.) So although the name >> _Troodon_ has been used for over 150 years, it hasn't been >> consistently used. >> >> Personally, I'd like to see _Troodon_ retained as a valid genus via >> nomination of a neotype (subject to ICZN approval). But unless that >> happens (which seems unlikely), the name _Troodon_ will indeed go the >> way of _Trachodon_. Sadly, _Ceratops_ and _Titanosaurus_ will >> inevitably suffer the same fate. |