Temporal range: Upper Cretaceous
An artist's illustration of Einiosaurus procurvicornis
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Order: Ornithischia
Family: Ceratopsidae
Tribe: Pachyrhinosaurini
Genus: Einiosaurus
Sampson, 1995
Species: E. procurvicornis
Binomial name
Einiosaurus procurvicornis
Sampson, 1995

Einiosaurus was a centrosaurid ceratopsian of the Upper Cretaceous period. Many Einiosaurus remains have been found together, stating that like the Pachyrhinosaurus and Centrosaurus, which lived at the same time, that it must have travelled in herds. It's name means Buffalo Lizard. It lived in northwestern Montana, USA.

Einiosaurus was a herbivorous dinosaur and grew to 6 m (19.8 ft) in length. It is typically portrayed with a low, strongly forward-curving nasal horn that resembles a bottle opener, though this may only occur in some adults. Supraorbital (over-the-eye) horns are low and rounded if present at all, as opposed to ceratopsids with prominent supraorbital horns such as Triceratops. A pair of large spikes projects backwards from the relatively small frill. Einiosaurus lived in an inland habitat.

Einiosaurus is an exclusively Montanan dinosaur, and all its known remains are currently held at the Museum of the Rockies in Bozeman, Montana. At least 15 individuals of varying ages are represented by three adult skulls and hundreds of other bones from two low-diversity (in species) bonebeds, which were discovered by Jack Horner in 1985 and excavated from 1985-1989 by Museum of the Rockies field crews. These bonebeds were originally thought to contain a new species of Styracosaurus and are referred to as such in the comprehensive taphonomic study by Ray Rogers. In 1995 Scott D. Sampson formally described and named Einiosaurus procurvicornis from this material, as well as Achelousaurus horneri, also from a bonebed in this region.

A six metre long Einiosaurus Procurvicornis

The placement of Einiosaurus within Centrosaurinae is problematic due to the transitional nature of several of its skull characters, and its closest relatives are either Centrosaurus and Styracosaurus or Achelousaurus and Pachyrhinosaurus. The latter hypothesis is supported by Horner and colleagues, where Einiosaurus is the earliest of an evolutionary series in which the nasal horns gradually change to rough bosses, as in Achelousaurus and Pachyrhinosaurus which are the second and third in this series. The frills also grow in complexity. Regardless of which hypothesis is correct, Einiosaurus appears to occupy an intermediate position with respect to the evolution of the centrosaurines.

The Northern White Rhinoceros is the only animal today that has an Einiosaurus like horn. They're were two individuals one in Dvur Králové Zoo and one female lived in the San Diego Zoo but both died.

NWRhino with an Einiosaurus like horn.jpg

In popular culture

  • Einiosaurus appeared on Dinosaur Planet.
  • Einiosaurus appeared on Dinosaur Train.


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