Re: Nomenclature

["T. Mike Keesey" <tkeese1@gl.umbc.edu>]

> I've been wondering...
> Is there a distinction between the correct or preferred uses of the
> following terms (which appear to be used interchangeably)?

In most of these cases, the first term encompasses a wider group than the
second one.

> ceratopian vs. ceratopid
(or ceratopsian vs. ceratopsid)
The first includes all animals sharing more recent ancestry with
_Ceratops_ than with _Pachycephalosaurus_.  This includes
_Psittacosaurus_, _Microceratops_, _Protoceratops_, _Leptoceratops_,
_Montanoceratops_, etc. as well as Ceratopsidae (which includes the
"advanced" ceratopsians -- the most recent ancestor of _Ceratops_ and
_Centrosaurus_, plus all of its descendants).

> tyrannosaur vs. tyrannosaurid
"Tyrannosaur" is an informal term, AFAIK, since there is no
"Tyrannosauria" (that I am aware of). It's often used as shorthand for
"tyrannosauroid", Tyrannosauroidea being tyrannosaurids plus a few
possible relatives (_Itemirus_, _Siamotyrannus_, _Stokesosaurus_, and
others have been proposed).

> stegosaur vs. stegosaurid
Stegosauria includes not only Stegosauridae, but the more "primitive"
Huayangosauridae and _Dacentrurus_.

> ankylosaur vs. ankylosaurid
Same deal. Ankylosauria includes not only Ankylosauridae, but also
Nodosauridae and _Minmi_.

> oviraptorosaur (?) vs. oviraptorid (oviraptorosaurid ?)
There is no such thing as an "oviraptorosaurid". (There is no genus
_Oviraptorosaurus_)

I've seen two definitions of Oviraptorosauria. I believe the more correct
one is "all animals sharing more recent ancestry with _Oviraptor_ than
with birds". This includes not only Oviraptoridae, but also
Caenagnathidae, _Microvenator_, and possibly Therizinosauroidea.

The other definition seems to exclude Therizinosauroidea (and possibly
_Microvenator_ as well).

> (?) vs. troodontid
The first is a symbol of punctuation. The second is a member of a clade of
coelurosaurs.

"Troodont", maybe? "Troodont" would be an informal term, since there is no
Troodontia.

> coelurosaur vs. coelurosaurid 
There is no such thing as a "coelurosaurid". (There is a "Coelurosaurus",
but it's a nomen nudum, it's probably just a typo, and no family was ever
named after it.)

> Are there such words as "tyrannosaurian"
Informally, yes.

> and "stegosaurian" ?
Definitely.

Check out my Index of Clades--

--T. Mike Keesey                                   <tkeese1@gl.umbc.edu>
DINOSAUR WEB PAGES -- http://www.gl.umbc.edu/~tkeese1/dinosaur/index.htm