Einiosaurus ‭(‬Buffalo lizard‭)

Short Info

Einiosaurus ‭(‬Buffalo lizard‭)

Phonetic : Ay-nee-o-sore-us.

Named By : Scott Sampson‭ ‬-‭ ‬1995

Diet : Herbivore

Size : Estimated 4.5 – 6 meters long

Type of Dinosaur : Ceratopsian

Type Species : E.‭ ‬procurvicornis‭ (‬type‭)

Found in : USA,‭ ‬Montana‭ ‬-‭ ‬Two Medicine Formation

When it Lived : Late Cretaceous, 74 million years ago

Einiosaurus, a small herbivorous centrosaurine ceratopsian dinosaur of the Upper Cretaceous (Campanian) stage, was a medium-sized herbivorous centrosaurine ceratopsian dinosaur. It was found in northwestern Montana’s Upper Cretaceous. Named ‘buffalo’ by Blackfeet Indian eini, the name also translates to Latinized Ancient Greek sauros. The specific Latin name (procurvicornis), means “with a forward-curving Horn”.


Einiosaurus skullMaarten Heerlien from The Hague, The Netherlands, CC BY-SA 2.0, via Wikimedia Commons


Einiosaurus was an herbivorous dinosaur. Although it is larger than Achelousaurus, it is far less sturdy. [In 2010, Gregory S. Paul calculated the Einiosaurus’ body length at 4.5m (15 ft), and its weight at 1.3 tons (1.3 long tons; 1.44 short tons). Both taxa are within the normal size range of Centrosaurinae.

Sampson identified several distinctive traits in 1995. The base of the nasal horn is very long, from front to back, is transversely flattened and, in some cases, strongly curves forwards. As far as the supraorbital “brown” horns are concerned, they are low and round with a convex outer surface. A single pair of large, curved spikes extends to the side of the skull frill’s rear edge.

Einiosaurus is different from other Centrosaurinae in that it has a longer-based, more procurved nasal hair and a supraorbital hair that is more rounded in the side view. Achelousaurus is the only one that has large parietal spikes, which aren’t directed sideways.

Einiosaurus, a centrosaurine that walked on all fours had a large head and beak. He also had a strong neck, strong forelimbs, a long tail, and a powerful tail.

Sampson described only the skull in 1995. He did not include the postcrania (the parts that surround the skull). The reason for this was the fact that the centrosaurines postcranial skull is “conservative”, which means it does not contain any of the parts behind the skull. There is very little variation between species. Sampson couldn’t find any traits that Einiosaurus was different from a generalised centrosaurine.

The largest known holotype skull has a length of 1.56m (5.1 ft). The snout is narrow and pointed. The paired nasal bones form the top of the nose. The core of the nasal Horn is found on their top surfaces. Apart from the skulls, eight nasal horns taken from both bonebeds were identified as Einiosaurus in 1995. Two of them were subadults. These images show how the animal’s horn developed over time. From the tip down, the core halves were fused and joined to form a single structure at the midline. The core showed a slight suture in the subadult stage. Subadult cores were transversely flattened, and small. They measured less than 12 cm (4.7 in). Six cores belonged to adults. Two distinct types were found. Two cores were both small and erect. Vertically directed. The four other horns were procurved and large, with a strong curving front. Adult horns were similar to the subadults in that they were transversely compressed, and had a longer base from front to back. They almost reached the frontal bones from behind.

Sampson compared Einiosaurus’ nasal horn with those of Styracosaurus and Centrosaurus. Numerous Centrosaurus nasal horns are well-known, with a wide variety of morphologies. They were found in large bonebeds. However, Einiosaurus’ horns are easily distinguished from them despite all the variation. They are less oval in cross-section than Centrosaurus horns, and more laterally compressed. The Centrosaurus adult horns have a more procurved shape than the nasal horns found in Centrosaurus bed. The Styracosaurus Horncores can be up to half a metre longer than Einiosaurus’s and are either erect to the rear or slightly recurved.

Centrosaurines had more than a horn on their snout. They also had supraorbital Horncores, horns that were above the eye sockets. These cores were created by the fusion of the palpebral bone and the postorbital bones. There were nine subadults or adults “brow horns”. All of them had the same build, being long, low and round. This is in contrast to the pointed horns that have an oval base found in most centrosaurines. It also differs from the supraorbital bosses found in Achelousaurus or Pachyrhinosaurus. Some Einiosaurus’ horns did however seem to approach bosses. There were five cases in which the horn was removed from an older person. Large holotype: The left side has a large pit that is eighty-five millimetres in length and sixty-four millimetres across. Sampson says this is consistent with a general trend among centrosaurines to absorb the brow horns again in later life. Styracosaurus specimens e.g. Instead of true horns, all known Styracosaurus specimens e.g. A rough bone mass is also found on the left side of the Einiosaurus Holotype’s rear postorbital area. All centrosaurines have their frontal bones folded so that they form a “double roof” with a “supracranial cavities” between. The upper layer is punctured by a fontanelle. This cavity extends sideways in Einiosaurus and continues below the brow horn. These passages are narrower and don’t reach the horns with Styracosaurus or Centrosaurus, but Pachyrhinosaurus has a similar extension. Sampson also outlined his views in 1995 on skull roofs. These skull roofs are difficult to interpret because of fusion. He stated that the frontal bones extended to the parietals and the paired postsorbitals were never in contact. The fontanelle was only partially supported by the parietal bone. The cavity floor is located at the frontal-parietal suture. A large foramen enters the braincase through the hole in the floor. Its function is unknown.

It has a narrow, pointed nose. The nasal horn is usually curved downward and is low. This resembles a bottle opener. If present, the supraorbital (overthe-eye), horns are short, triangular and low in top view. They are not as prominent as those of the chasmosaurines like Triceratops. The third epiparietal, a pair of large spikes that extend backwards from the frill’s relatively small size, is the third epiparietal. The frill edge is adorned with smaller osteoderms. The epiparietals that were the first are absent.

Source: Wikipedia