Temporal range: Late Cretaceous, 68–67.6Ma
Wu et al., 2007
|Species:||† E. xerinsularis|
Wu et al., 2007
Eotriceratops (meaning "dawn Triceratops") is a genus of ceratopsian dinosaurs which lived during the late Cretaceous period. Fossils of the only known species, Eotriceratops xerinsularis, have been found in the uppermost Horseshoe Canyon Formation, dating to about 67.6 million years ago. Possible additional specimens, which have been variously classified in the species Ojoceratops fowleri and Torosaurus utahensis, are known from the same time period in New Mexico and may also belong to Eotriceratops. The largest known skull is reported to have been around 3 metres (10 ft) long. It has been estimated that this specimen had a total length of about 9 meters (30 ft).
Eotriceratops was described by Xiao-Chun Wu, Donald B. Brinkman, David A. Eberth and Dennis R. Braman in 2007 and the type species is E. xerinsularis. The specific name, xerinsularis, means "dry island" and is a reference to the Dry Island Buffalo Jump Provincial Park where its remains were found.
Eotriceratops is known from a single incomplete skeleton found disarticulated in Dry Island Buffalo Jump Provincial Park in southern Alberta, Canada. The skeleton consisted of a partial skull including parts of the frill, large horns above the eyes, and a small horn above the nose, similar to the closely related Triceratops. Several neck and back vertebrae, as well as several ribs, were also recovered. Because the specimen was found in weakly bedded shale, many of the bones were badly crushed. It differs from other chasmosaurine ceratopsians in unique features of the skull bones, such as an unusually pronounced jugal horn and extremely elongated, flattened and spindly epoccipitals (the bones lining and often protruding from the edge of the frill), similar to Torosaurus utahensis. Most distinctively, Eotriceratops had a pronounced vertical process on its premaxilla where it contacted the nasal bones not seen in its relatives; though some Triceratops specimens have a similar process, it is not as tall. The horns above the eyes were forward-curving and about 80 centimetres (2.6 ft) long. There appeared to have been bite marks above the eye, near the base of the left horn.
- Wick, S. L.; Lehman, T. M. (2013). "A new ceratopsian dinosaur from the Javelina Formation (Maastrichtian) of West Texas and implications for chasmosaurine phylogeny". Naturwissenschaften. in press (7): 667. Bibcode:2013NW....100..667W. doi:10.1007/s00114-013-1063-0.
- Wu, X-C.; Brinkman, D.B.; Eberth, D.A.; Braman, D.R. (2007). "A new ceratopsid dinosaur (Ornithischia) from the uppermost Horseshoe Canyon Formation (upper Maastrichtian), Alberta, Canada.". Canadian Journal of Earth Science 44 (9): 1243–1265. doi:10.1139/E07-011.
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