The Ceratopsid family is divided in two subfamilies: the three-horned/long-frilled one and the single-horned/short-frilled one. note Among three-horned/long-frilled ceratopsids you'll see Chasmosaurus, Pentaceratops & Torosaurus more often; less-frequently, Arrhinoceratops & Anchiceratops. About the single-horned kinds, other than the multi-spiked Styracosaurus the chances are to meet Monoclonius or Centrosaurus (which could actually be the same animal), and less-frequently "Brachyceratops" & Avaceratops. Since the 1990s the no-horned Pachyrhinosaurus has also become a frequent sight, as well as Einiosaurus. Some of them have even made occasional apparitions in fictional media other than in documentaries.
I'm the real Bullsaur... or am I just too old?: Torosaurus
- Despite its size and popularity Triceratops is not the most striking-looking horned dinosaur: it is larger than almost every other ceratopsid and had long frontal horns, all right, but its nasal horn is very short (in some individuals looks like a simple bump) and its bony shield is kinda uncospicuous, being quite smooth, short, and with no promiment spikes (Styracosaurus or Centrosaurus have much longer nasal horn and spiked shields). Not counting the fact that some close Trike's relatives show much more impressively extended frills, sometimes with an amazingly angular edge: ex. Chasmosaurus, Pentaceratops, and the most impressive of all, Torosaurus. Although relatively simple in shape, the frill of the torosaur is so vast that make its skull reaching 2.5 m in length, more than a fully-grown human: until the late 1990s it was the biggest known head of any land-animal ever. Unlike Chasmosaurus and Pentaceratops which had relatively short frontal horns, those of Torosaurus were often as long as those of Triceratops or even a bit more — making the adult "toro" an astounding view even for a hungry Tyrannosaurus rex. Even though all ceratopsids lived in Late Cretaceous, always in North America (except one or two), Torosaurus latus was one of the very few that lived alongside Triceratops. Commonly thought to mean bull lizard (toro = bull in Spanish): a very apt name, only Torosaurus actually means "perforated lizard". This because it has holes in its bony frill, unlike Triceratops. The same size of Triceratops or even bigger (up to 9 tons extimated), Torosaurus is also considered one of the closest Triceratops relatives. In fact they are so similar, it has been proposed at the end of the 2000s that Torosaurus was just a grown-stage of Triceratops; since the name Triceratops has been created before Torosaurus, the latter could get the same fate of "Anatotitan". Whatever the case, the torosaur is recognizable thanks to its huge but smooth shield (many triceratopses had small bumps all around the edge of it): while the Triceratops frill covered only the neck of the animal, the Torosaurus one covered even its shoulders when put horizontally; when its head was lowered, the frill automatically raised in an upright position, making the animal looking bigger if seen from the front, possibly scaring predators or rivals. Apart from the frill Torosaurus and Triceratops had very similar heads, with two long bull-like frontal horns and one much shorter on the nose. If the two animals were one and the same, however, the longer frill might just be an old-age-related trait. Torosaurus and Triceratops were portrayed as two different animals in the last episode of Walking with Dinosaurs (justified though, since was made in year 1999). Interestingly, is Torosaurus which has the main role in the story - Triceratops appears only in the form of one carcass. Considering the more-striking look of the Toro, this choice was wittily made to avert Stock Dinosaurs while playing straight Rule of Cool at the same time.
Five horns...or not?: Pentaceratops
- Despite many of the most well-known ceratopsians had the usual saurus ending (Torosaurus, Styracosaurus, Centrosaurus, Pachyrhinosaurus, Chasmosaurus, Einiosaurus), most described genuses have the same suffix of the Great-Stock member. -ceratopses do abund here: after Triceratops (three horned face) and Protoceratops (first horned face), the most well-known is Pentaceratops (five-horned face). But did it really had five horns? Well no. They were only three. The other two horns actually were simple protrusions arising from each cheekbone - a common ceratopsian trait, but particularly evident in Pentaceratops. One of the classic long-frilled ceratopsids, Pentaceratops was pratically the intermediate form between Torosaurus and Chasmosaurus: smaller than Torosaurus but bigger than Chasmosaurus, lived before the former but after the latter. Its horns were shorter than Torosaurus but more developed than many Chasmosauruses. Its frill was neither elliptical / smooth like the Toros one, nor triangular / complex like the Chasmos: it was rectangular and lightly serrated around its whole perimeter. Known since the first half of the XX century from remains discovered in Texas, Pentaceratops gained more attention in the 1990s after the discovery of a gigantic skull which was attributed to its genus. Before that, Torosaurus, with its 2.5 m long skull, used to bear the record for the biggest-headed land animal ever; this putative pentaceratops skull was 3 m long. Science Has Marched On however, and this specimen has been deemed a separate animal in January 2011, meaningfully-named Titanoceratops.
- As a whole, Centrosaurs - Styracosaurs - Pachyrhinosaurs - Chasmosaurs might be considered the predecessors of Triceratops. The latter was elephant-sized, lived 70-65 million years ago just before the mass-extinction and shared its world with the mythical Tyrannosaurus rex; the former were rhino-sized or only a bit larger, lived 80-70 million years ago, and had to be pleased with its humbler relatives (Albertosaurus, Gorgosaurus, and Daspletosaurus). If you see a battle between a tyrannosaurid and a ceratopsid in some CGI documentary, expect to see Triceratops instead of the less-gigantic CentroStyracoPachyrhinoChasmosaurs and other less-known contemporaries, like Anchiceratops and Arrhinoceratops. The first one was very Chasmosaurus-like with a similar angular frill but entirely smooth laterally and entirely tubercled at its top. The second has a similar ornamentation but a shorter frill. Anchiceratops ("almost-'Ceratops'", see below) is nonetheless abundant in fossil record, while Arrhinoceratops is a rarer find; when discovered was initially thought to lack the nasal horn, hence its prefix arrhino which means no horns on the nose. One fragmentary ceratopsid which was often confused with Chasmosaurus in the past is "Eoceratops"("dawn horned face"): this one was indeed one of the first true ceratopsids, living the same time of Chasmosaurus proper. A deceptively chasmosaurine-looking ceratopsian found in the late 1990s that roamed North America well before the others (in Middle Cretaceous) was actually more primitive to be a true ceratopsid, Zuniceratops.
- Who knows which is the official prototype of the Ceratopsid family? Well just Ceratops. More precisely, Ceratops montanus ("mountain-living horned face"). Found by Marsh during the Bone Wars, it was his first horned dino, but has left only a fragmentary skull. It could be Chasmosaurus or something else, and has been largely ignored by everyone. Not the same about "Agathaumas sylvestris" (meaning "great wonder of the forests"). This animal was also found during the wars, this time by Cope; only some pieces of skeleton are known but not skulls, and since non-cranial remains are not diagnostic enough, Agathaumas is impossible to describe. Many suspect its only a Triceratops individual. And yet, it has had a famous appearance in the 1925 movie version of "The Lost World" (one of the first apparition of dinosaurs in cinema), in which it was portrayed with a Triceratops look. That apparition made it rather popular at the time, but now has got quite forgotten except among old-movies lovers.
I'm the real Rhinosaur... or am I just too young?: Monoclonius,
- Monoclonius has been a very early discover, made in the XIX century during the Bone-Wars, but now is regarded by many as the juvenile-stage of Centrosaurus and its relatives. If so, then Centrosaurus would become invalid, because "Monoclonius" was the first name created. Two of the most familiar ceratopsid names, Torosaurus and Centrosaurus, risk now to get the same former fate of Brontosaurus. "Monoclonius" (which doesn't mean "one horn" as sometimes said, but "one sprout") was slightly smaller than Centrosaurus but with the same rhinoceros-like appearence (long nose-horn and no real front-horns), and its frill had not the famous downwarding "hooks" of Centrosaurus (or it had them much shorter). While Triceratops was officially described by Marsh, "Monoclonius" was one of the few prominent bone-war dinosaurs first-described by Cope. Unlike alot of other "stock obscure" dinosaurs, Monoclonius has a notable and relatively recent appearance in popular culture: 1984's Prehistoric Beast by Phil Tippett, who would go on to be a supervisor and consultant for the Jurassic Park films.
- Another less-known unicorn ceratopsid is Brachyceratops ("short horned-face"); found in the early XX century, it is known only from juveniles, and like Monoclonius, could just be a young stage of another ceratopsid. On the other hand, Avaceratops found in 1986 is a valid animal despite its small size (3 m long, one of the smallest known members of the ceratopsid family). This was a horned dinosaur of uncertain affinites whose name means Avas horned face (its discoverer named it from his wifes name). Even though resembles a miniature Monoclonius (it was probably a basal centrosaurine), Avaceratops actually has a thing that makes it very similar to Triceratops: a round tubercled frill with no openings in it. Described in the 2000s, Albertaceratops ("Alberta horned face", originally confused with the similar Medusaceratops) was also probably a basal centrosaurine, but with a thing that surprised scientists: it had long frontal horns just like chasmosaurines like Triceratops, but also a small relief on its one (rather than a proper horn), and two hook-like tubercles on its frill-top like a Centrosaurus.
- Well, its true: ceratopsids have really bizarre hairdos. The most astonishing is, needless to say, that of Styracosaurus, with its multiple horns protruding from the frill. But some relatives made even their frontal horn a very odd-looking thing: for example Einiosaurus procurvicornis. Discovered in 1994, it was initially believed a new Styracosaurus species, but with only two terminal spikes on its shield. The strange thing here is the nasal horn: strongly curved, thickened and pointing forwards (Einiosaurus procurvicornis means "buffalo-lizard with the horn curving forwards"), as the animal could signal its target like a pointer dog more realistically, its shape could have been for ornamental purpose. Another related ceratopsid was also described in 1994: Achelousaurus ("Achelous lizard)": very similar of Pachyrhinosaurus, it shared with the latter the same thickened nose, but had a longer couple of frill-spikes and a less-complex frill than the pachyrhinosaur. Together, Einiosaurus and Achelousaurus are among the closest relatives of Pachyrhinosaurus, and they together make what is believed the most-recent & advanced centrosaurine subgroup, the Pachyrhinosaurini.
An unexpected variety: Ceratopsids found in the 2010s
- As recently as The New '10s, many new ceratopsid species have been described, with various frill-shapes, and the classification of the whole family has strongly improved since that. Rubeosaurus, for example, was very similar to Styracosaurus (and originally considered a species of the latter just like Einiosaurus above), but with shorter frill-spikes and longer nasal horn. Diabloceratops ("devil horned-face") and Machairaceratops ("sword-horned face") coupled the pair of long frontal horns with two long frill-spikes, while the nose-horn was almost missing. Nasutoceratops had long curved brow-horns and a prominent hornless nose, incidentally similar to the ancestral "missing link" Zuniceratops. One of the most spectacular is Kosmoceratops: similar to Chasmosaurus, it shows an entire set of curved hooks protruding from the frill-top like a fanciful fringe. While Sinoceratops ("Chinese horned face") was very similar to Centrosaurus; even though incomplete, it's the only confirmed ceratopsid found in Asia to date, and has even captured in 2018 the interest of the Jurassic Park productors who chose to show it in Jurassic World: Fallen Kingdom together with other more famous dinosaurs. Slightly before all these ones was described a more normal-looking ceratopsid, Eotriceratops ("dawn Triceratops", not to be confused with "Eoceratops" above): extimated 11 meters long, it is one of the biggest ceratopsid known so far, as large as the largest Triceratopses.