Einiosaurus

Einiosaurus is a medium-sized herbivorous centrosaurine ceratopsian dinosaur from the Upper Cretaceous (Campanian stage) of northwestern Montana. The name means 'buffalo lizard', in a combination of Blackfeet Indian eini and Latinized Ancient Greek sauros; the specific name (procurvicornis) means 'with a forward-curving horn' in Latin.

Description
Einiosaurus was a herbivorous dinosaur. In 2010 Gregory S. Paul estimated its body length at 4.5 metres, its weight at 1.3 tonnes.[1] Its snout is narrow and very pointed. It is typically portrayed with a low, strongly forward and downward curving nasal horn that resembles a bottle opener, though this may only occur in some adults. The supraorbital (over-the-eye) horns are low, short and triangular in top view if present at all, as opposed to the chasmosaurines, such as Triceratops, which have prominent supraorbital horns. A pair of large spikes, the third epiparietals, projects backwards from the relatively small frill. Smaller osteoderms adorn the frill edge. The first epiparietals are largely absent.

Paleobiology
Low-diversity and single-species bonebeds are thought to represent herds that may have died in catastrophic events, such as during a drought or flood. This is evidence that Einiosaurus, as well as other centrosaurine ceratopsians such as Pachyrhinosaurus and Centrosaurus, were herding animals similar in behavior to modern-day bison or wildebeest. In contrast, ceratopsine ceratopsids, such as Triceratops and Torosaurus, are typically found singly, implying that they may have been somewhat solitary in life, though fossilized footprints may provide evidence to the contrary.[2] In 2010, a study by Julie Reizner of the individuals excavated at the Dino Ridge site concluded that Einiosaurus grew quickly until its third to fifth year of life after which growth slowed, probably at the onset of sexual maturity.

Like all ceratopsids, Einiosaurus had a complex dental battery capable of processing even the toughest plants.[4] Einiosaurus lived in an inland habitat.[5]

Einiosaurus fossils are found in the upper part of the Two Medicine Formation of Montana, dating to the mid-late Campanian stage of the late Cretaceous Period, about 74.5 million years ago.[6][7] Dinosaurs that lived alongside Einiosaurus include the basal ornithopod Orodromeus, hadrosaurids (such as Hypacrosaurus, Maiasaura, and Prosaurolophus), the ankylosaurs Edmontonia and Euoplocephalus, the tyrannosaurid Daspletosaurus (which appears to have been a specialist of preying on ceratopsians), as well as the smaller theropods Bambiraptor, Chirostenotes, Troodon, and Avisaurus. Einiosaurus lived in a climate that was seasonal, warm, and semi-arid. Other fossils found with the Einiosaurus material include freshwater bivalves and gastropods, which imply that these bones were deposited in a shallow lake environment.