Re: Ceratopsian Systematics [was: Avaceratops and Ceratops (was Re: THE NEW I...

[Dinogeorge@aol.com]

In a message dated 1/26/00 10:51:47 AM EST, znc14@TTACS.TTU.EDU writes:

<< Timothy Williams wrote (please don't take offense at the rant here, Tim!):
 >Could _Avaceratops_ 
 >be a juvenile _Ceratops_?  (For those who believe that _Ceratops_ is a 
 >defunct genus, read on...)
         Only if _Ceratops_ were valid. What the specimen really shows,
 according to Tom Lehman, all-too-rarely acknowledged ceratopsian expert, is
 that _Ceratops_ is not only generically indeterminate, but indeterminate at
 the "family" level as well. >>

In which case, if Ceratops is to be regarded as a nomen dubium, then the 
names Ceratopidae and Ceratopinae become nomina dubia as well, and must be 
replaced. As I recall, the next available family level taxa created within 
this group are Lambe's Chasmosaurinae and Centrosaurinae, and since they were 
created in the same work, we have a choice about which one we can use for the 
family name. There are questions about the validity of the name Centrosaurus 
(it's preoccupied, or may require a petition to retain as a valid name), so 
it's better to use the unquestionably valid Chasmosaurus as the type genus of 
the family. We would then change the name Ceratop[s]idae to Chasmosauridae 
(the family-level ending makes it a new combination), which would have, say, 
two subfamilies. One must be named Chasmosaurinae (the one containing 
Chasmosaurus, of course), the other Centrosaurinae (or whatever name it 
finally gets, if Centrosaurus is shown to be incorrect). My own preference 
for the name of that second subfamily is Pachyrhinosaurinae, which is the 
next available name and doesn't have potential nomenclatural problems. The 
doubtful genus Ceratops would then be classified as Chasmosauridae incertae 
sedis. (After all, it's certainly a neoceratopian of some kind.)