English: Torosaurus latus Marsh, 1891 - fossil ceratopsian dinosaur skull from the Cretaceous of Montana, USA. (MOR 981, Museum of the Rockies, Bozeman, Montana, USA)

Ceratopsians are the "horned dinosaurs". They were large, quadrupedal, herbivorous dinosaurs having a beaked skull and a frill - an extension of bone behind the skull that partially covered the neck. Ceratopsian dinosaurs are known from the Jurassic and Cretaceous. The last members of the group died out at the Cretaceous-Tertiary boundary, 65 million years ago.

This is a left lateral view of a partial skull of Torosaurus latus from Montana's Hell Creek Formation of near-latest Cretaceous age. Some researchers consider Torosaurus to be synonymous with Triceratops, but they are probably separate genera (Scannella & Horner, 2010; Longrich & Field, 2012).

Classification: Animalia, Chordata, Vertebrata, Reptilia, Archosauria, Dinosauria, Ornithischia, Marginocephalia, Ceratopsia, Ceratopsidae

Stratigraphy: Hell Creek Formation, Maastrichtian Stage, Upper Cretaceous

Locality: undisclosed site ("Toro I") in Dawson County (= Museum of the Rockies locality # HC-188), eastern Montana, USA

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References cited:

Scannella & Horner (2010) - Torosaurus March, 1891, is Triceratops March, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny. Journal of Vertebrate Paleontology 30: 1157-1168.

Longrich & Field (2012) - Torosaurus is not Triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy. Public Library of Science One 7(2): e32623. 10 pp.

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Info. at:

en.wikipedia.org/wiki/Torosaurus