A distinctive chasmosaurine similar in size to a large rhino (total length approximately 3.5 m), Anchiceratops ornatus was a heavily built species with a particularly short tail and robust limbs [adjacent image from wikipedia. Not bad, but it doesn’t depict the rear margin of the frill or epoccipitals correctly]. Barnum Brown first discovered this species in 1912 in the Campanian Dinosaur Park Formation, and named it in 1914. Brown’s specimen had long, erect brow horns, leading some to suggest that it was a male. A supposed second species, A. longirostris, was named by Charles M. Sternberg in 1929 for a more lightly built specimen with shorter and more forwardly inclined brow horns from the Maastrichtian Horseshoe Canyon Formation. This specimen seems similar enough to the A. ornatus holotype to belong to the same species, though the differences have led some researchers to suggest that it represents a female (Lehman 1990, Dodson 1996).
The best Anchiceratops specimen is the articulated, complete skeleton (NMC 8538: it lacks only the skull) collected by Sternberg in 1925 near Rumsey, Alberta, and today displayed at the Canadian Museum of Nature in Ottawa [the attached pic, ripped from a pdf of Lull (1933), is the best image I have of it, sorry. The Greg Paul reconstruction shown below is based on this specimen]. When discovered, it lay on its right side, but during mounting its orientation was reversed, such that the right side is the one that projects outwards. There is hardly any published information on this specimen: Lull (1933) provided a terse description and apparently expected a longer account to appear later on. Authors have typically noted the heavy construction of its limbs, and the shortness of its tail. There are only 38 caudal vertebrae, as opposed to a more typical 45-46 (Lull 1933, Dodson 1996). The specimen confirms that, in articulated ceratopsian skeletons, the ribs sweep strongly backwards: an observation that has obvious implications for the position of the shoulder girdle. The skull placed on the skeleton is a copy of the 1929 specimen.
Unlike Pentaceratops and some species of Chasmosaurus, Anchiceratops lacked a concavity on the frill’s rear margin and its parietal fenestrae were relatively small. Six large epoccipitals bordered the frill’s dorsal edge and two smaller epoccipitals were located near the frill’s dorsal edge and along its midline. It had a long snout and a small, low nasal horn. In contrast to many other ceratopsians, Anchiceratops fossils come from sediments deposited in low-lying marshy environments, suggesting that it was an inhabitant of swampy regions. Langston (1959) suggested that the long face may have ‘assisted breathing while the animal crossed marshy ground or waded in shallow water’ (p. 10), and that the frill and large, heavy epoccipitals may have counter-balanced the snout when the animal was holding its snout up high, but this sounds unlikely.
For previous Tet Zoo articles on ceratopsids see…
- Pentaceratops: that’s quite the skull
- A month in dinosaurs (and pterosaurs): 3, Minotaurasaurus and giant chasmosaurines
Refs – –
Dodson, P. 1996. The Horned Dinosaurs. Princeton University Press, Princeton, NJ.
Langston, W. 1959. Anchiceratops from the Oldman Formation of Alberta. Natural History Papers, National Museum of Canada 3, 1-11.
Lehman, T. M. 1990. The ceratopsian subfamily Chasmosaurinae: sexual dimorphism and systematics. In Carpenter, K. & Currie, P. J. (eds) Dinosaur Systematics: Approaches and Perspectives. Cambridge University Press, Cambridge, pp. 211-229.
Lull, R. S. 1933. A revision of the Ceratopsia or horned dinosaurs. Memoirs of the Peabody Museum of Natural History 3, 1-175.