ceratopinae

Ceratopinae

     Ceratopinae includes, as described before, ceratopids with prominent brow horns, short nose horns, long squamosals, and a projection in the front of the nasal fenestra. Ceratopines tend to larger than centrosaurines, and are the only ceratopid group known to have made it to the end of the Mesozoic. As with centrosaurines, there may be several groupings within Ceratopinae. The best supported is "Chasmosaurini", which is characterized by very large fenestrae (or holes or windows) in the parietal, meaning the frill is only supported by the median bar, the two side bars, and the rear bar of the parietal, something like this if viewed from the top:
                                           +--------+--------+
                                             \            |            /
                                               \          |          /
                                                 \        |        /
                                                   \      |      /
                                                    +--+--+

There may be another group or groups in Ceratopinae; I tentatively recognize a possible grouping called "Triceratopini", which holds all ceratopines closer to Triceratops than to Chasmosaurus. This group has much smaller windows in the frill, a tendency towards consolidation of these windows, and a tendency toward a shorter frill, as shown in the short, solid frill of Triceratops.

Ceratopinae:

Taxon or Taxa:	Time\Place:	Comments:
Anchiceratops ornatus Brown, 1914	late middle Campanian-early Maastrichtian (LK) of Alberta	Anchiceratops is rather modest in frill, especially when compared to the chasmosaurinids. It has moderately-sized windows, with six short projections on the rear of the frill and two distinctive knobs of bone on the top surface of the frill, near the rear edge.

Ceratopinae i.s.:

Taxon or Taxa:		Time\Place:	Comments:
?"Bison" alticornis (N.D.) Marsh, 1887		late Maastrichtian (LK) of Wyoming	This usually forgotten name is what Marsh initially named what possibly are remains (two horn cores) of Triceratops, thinking they came from a bison. It is now probable that they came from a ceratopine, but which one produced them is not discernable.
Ceratops montanus (N.D.) Marsh, 1888 (?Chasmosaurus or Avaceratops)		late middle Campanian (LK) of Montana	Historically significant as the namesake of Ceratopidae, this animal is very poorly known. Its type consists of horn cores and skull fragments, which are similar to both Chasmosaurus and Avaceratops bones. New material may belong to it.
Polyonax mortuarius (N.D.) Cope, 1874		late Maastrichtian (LK) of Colorado	Polyonax is based on horn fragments and vertebrae. Not surprisingly, it is very obscure.
"Triceratops":	"T." galeus (N.D.) Marsh, 1889	late Maastrichtian (LK) of Colorado	This is an indeterminate ceratopine based on a nasal horn core.
	"T." ingens (N.D.) Lull, 1915	late Maastrichtian (LK) of Wyoming	"T." ingens is based on a partial skull and postcranium, neither of which allow it to be positively assigned to Triceratops proper.
	"T." sulcatus (N.D.) Marsh, 1890	late Maastrichtian (LK) of Wyoming	This animal is based on a partial skull.

"Chasmosaurini": If one wanted to be a minimalist, all of these genera could be put into Chasmosaurus.

Taxon or Taxa:		Time\Place:	Comments:
Agujaceratops mariscalensis Lucas, Sullivan, and Hunt, 2006 (originally Chasmosaurus mariscalensis [Lehman, 1989])		late Campanian (LK) of Texas	Originally assigned to Chasmosaurus, this species has been difficult to place because it is very similar to Pentaceratops in some ways (although its frill is somewhat shorter and more erect than that of Pentaceratops), and was found far from the classic Chasmosaurus stomping grounds. Like Pentaceratops, there is a deep indentation on the rear bar of the frill. To be on the safe side, it was given its own genus.
Chasmosaurus: Lambe, 1914 (originally Protorosaurus Lambe, 1914)	C. belli (type) (Lambe, 1902 [originally Monoclonius])	late middle Campanian (LK) of Alberta	C. belli was a common Judithian dinosaur. There appears to be two forms, a short-horned and a long-horned form ("C. canadensis", "C. kaiseni"). These may be females and males. Chasmosaurus as a whole also has large epoccipitals (nodules of bone on the frill) at the top corners of the frill.
	C. russelli Sternberg, 1940 (?C. belli)	early late middle Campanian (LK) of Alberta	C. russelli closely resembles C. belli, but has a Y-shaped rear parietal bar, and has three large epoccipitals along the rear bar of the frill. It also is larger and often has a large nasal horn. It too may fall within the variation of the type species.
	C. irvinensis, Holmes, Forster, Ryan, and Shepherd, 2001	latest middle Campanian (LK) of Alberta	From the uppermost "Judithian" comes this new species. It is known from three skulls; distinctive features include no brow horns, a broad snout, smaller parietal fenestrae than other Chamsosaurus species, and an unusual configuration of epoccipitals (there appears to be 10, with the middle 8 flattened, curved forward and up, and fused to each other at the edges, forming a funky serrated leading edge to the back of the frill).
Pentaceratops sternbergi Osborn, 1923		early late Campanian (LK) of New Mexico	A large ceratopine with a large skull relative to that large body, Pentaceratops has one of the most impressive frills of any ceratopid. Its frill is large and long but contains wide windows, and has an indentation on the midline, like those of Chasmosaurus russelli and Agujaceratops, which has two large epoccipitals projecting in and forward, and two smaller ones projecting down and over the frill for a very short distance. It holds the individual record for longest head for a land animal (one new specimen is over three meters long), but Torosaurus as a whole appears to show a longer average head.

"Triceratopini":

Taxon or Taxa:		Time\Place:	Comments:
Arrhinoceratops brachyops Parks, 1925		early Maastrichtian (LK) of Alberta	Arrhinoceratops is based on a skull from an old individual, which overall is similar to that of Triceratops. While the name claims this animal has no nose horn, it does have one.
Eotriceratops xerinsularis Wu X., Brinkman, Eberth, and Braman, 2007		middle Maastrichtian (LK) of Alberta	Eotriceratops is based on a partial skull and vertebrae from high in the Horseshoe Canyon Formation. The skull is quite a bit like that of Triceratops, except the frill is much thinner (unfortunately, it's not complete).
Triceratops: Marsh, 1889	T. horridus (type) (Marsh, 1889 [originally Ceratops])	late Maastrichtian (LK) of Wyoming, Montana, S. Dakota, Colorado, Alberta, and Saskatchewan	Triceratops is easily within the top five of most famous dinosaurs. Its combination of large size, bony frill, and long, powerful brow horns has impressed itself upon generations of children, and its contemporary Tyrannosaurus rex provides high drama from the contest of the most powerful predator versus the most powerful herbivore. Its brow horns were well over a meter in length when sheathed with horn, and a row of epoccipitals around the outside of the solid, window-less frill would have given this animal a jagged-looking head. Although the frill was more likely for display than for defense (and could have had additional functions like thermoregulation, or even directing of sound to the ears), the horns would have been excellent defensive weapons, especially when powered by the elephant-sized animal. At one time the overall shortness of the frill led many workers to classify Triceratops as a "short-frilled" ceratopid, but it is more likely that the frill is actually secondarily shortened, with typically long ceratopine squamosals. It may, however, be more closely allied with the similarly solid-frilled Avaceratops than with the ceratopines. At one time over fifteen species had been named, but most of these were later shown to be based either on variations within that which would be expected in a gregarious animal, including differences between sexes and ages, or preservational problems. Of the two commonly accepted species, T. prorsus is the more common species in northern faunas (and there may be more species in the relatively poorly-known Canadian material), while T. horridus is more common in more southerly formations. Over fifty skulls are known, but no complete skeletons have been found; all mounted Triceratops skeletons are composites. For example, the mount at the Science Museum of Minnesota, which is the world's largest Triceratops mount, is based on two similarly-sized individuals. Triceratops was the most common dinosaur of the Lancian age (as you can probably find out from any paleontologist who works in rocks of the latest Cretaceous of Montana, Wyoming, S. Dakota, etc.), and may have been one of the very last to go extinct at the end of the Mesozoic.
	T. prorsus Marsh, 1890
Diceratus hatcheri Mateus, 2008 (Hatcher, 1905 [species name after Lull, 1905 (originally Diceratops)])		late Maastrichtian (LK) of Wyoming	Diceratus (under the guise of Diceratops) was long considered to be a Triceratops individual, albeit a poorly preserved and probably pathological individual. It has since been reinterpreted as a close relative of Triceratops, but not the same, as shown by the small parietal windows. This animal may have descended from a close ancestor of Triceratops. The name Diceratops is preoccupied by a hymenopteran insect (think wasps, bees, and ants) (Foerster, 1868; ironic since the researcher who brought this dinosaur back is named Forster [Cathy]), necessitating the change.
Torosaurus: Marsh, 1891	T. latus (type) Marsh, 1891	late Maastrichtian (LK) of Wyoming, Montana, S. Dakota, and Saskatchewan	Torosaurus owns the distinction of having the one of the longest heads of any known land animal, sometimes the size of a compact car. Obviously a very large ceratopine, it was a less common contemporary of Triceratops. Because ceratopid postcrania are so similar, and because complete Triceratops remains have not yet been discovered, some Triceratops mounts may incorporate Torosaurus material. Seven skulls are known for T. latus, although none of them is complete (it's a big weirdly-shaped object with a thin frill, after all). The frill is V-shaped, as opposed to the rounder, stockier frills of Triceratops and Diceratus. There appears to be a second species of Torosaurus in the known material, T. utahensis, which has a shorter frill. It is best known from more southern localities.
	T. utahensis (Gilmore, 1946 [originally Arrhinoceratops])	Late Maastrichtian (LK) of Utah, Colorado, New Mexico, and Texas

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