Euoplocephalus

*Euoplocephalus tutus*

* Jurassic Park Institute Artwork
* Robert F Walters Artwork

***Euoplocephalus*** (Greek, "well-armed head") belonged to the Ankylosaur family. It lived during the late Cretaceous period until the great extinction. It was one of the final species in a long line of evolving Ankylosaurs. *Euoplocephalus* often traveled in herds of which offered protection to itself. It is very likely it was similar in appearance to it's relative, *Ankylosaurus*, except that the Euoplocephalus had armour on its head, unlike the Ankylosaurus.

*Euoplocephalus* body was covered in "armor", which was actually bone plating, which protected it from predators. Its tail was a giant club, much like a mace, that could be used as a weapon to defend itself from predators. It is believed that it would lay down and pull its limbs under the boney plates to keep itself from being damaged, and then it would swing its tail until a predator lost interest or became mortally injured by the club like tail. Some paleontologists believed this was such a good adaptation that if the great extinction didn't occur *Euoplocephalus* might still have been alive today.

## Description

The Euoplocephalus was around 6-7 meters long, medium sized for an Ankylosaurid, and lived around the same time as its more famous cousin, the Ankylosaurus. It's spiked and knobby armor probably protected it from lots of different predators, but would be doubtful against the ferocious bite of a Tyrannosaurus, or other large predator. Like all Ankylosaurids, Euoplocephalus probably grazed on low-lying plants, such as primitive bushes, and ferns.

## Discovery and Species

Canadian paleontologist Lawrence Morris Lambe discovered the first specimen on 18 August 1897 in the area of the present Dinosaur Provincial Park, in the valley of the Red Deer River, Alberta, Canada. In 1902, this fossil, **CMN 210** (also NMC 210) was designated as the holotype specimen of the type species *Stereocephalus tutus*. This specimen consists of the upper part of a cranium and a transverse series of five scutes that were part of a cervical half ring. The generic name was derived from Greek στερεός, *stereos*, "solid", and κεφαλή, *kephalè*, "head", which refers to the formidable armour. However, the genus name was already *preoccupied* — the name had already been given to an insect, the beetle *Stereocephalus* Lynch 1884 — so Lambe changed it to *Euoplocephalus* in 1910, with as *combinatio nova* (new combination name) *Euoplocephalus tutus*. The type species remains *Stereocephalus tutus*. In 1915, Edwin Hennig classified *E. tutus* under the genus *Palaeoscincus* Leidy 1856, coining a *Palaeoscincus tutus*. Today however, *Palaeoscincus* is considered to be a *nomen dubium* based on indeterminate ankylosaurian teeth. In 1964, *Euoplocephalus* was by Oskar Kuhn referred to *Ankylosaurus*, as a *Ankylosaurus tutus*.

The genus name *Euoplocephalus*, meaning "well-armed head", is derived from the Greek words *eu* (εὖ) meaning "well", *hoplo*~ (ὁπλο~) meaning "armed", and *kephale* (κεφαλή) meaning "head". This name has been misspelled more than a dozen different ways in formal scientific literature. The specific name *tutus* means "safely protected" in Latin. The only valid species known today is *Euoplocephalus tutus*.

## Classification

In 1910, Lambe assigned *Euoplocephalus* to the Stegosauria, a group then encompassing all armoured dinosaur forms and thus having a much wider range than the present concept. In 1917, Charles Whitney Gilmore assigned it to the Ankylosauridae. Today, *Euoplocephalus* is still seen as an ankylosaurid, but as a member of the Ankylosauria, not the Stegosauria. It is likely also a member of the derived subgroup Ankylosaurinae. The recent splitting of the ankylosaurid Campanian material of North America has complicated the issue of the direct affinities of *Euoplocephalus*. Penkalski (2013) performed a small phylogenetic analysis of some ankylosaurine specimens. The only *Anodontosaurus* specimen that was included in this analysis was its holotype. *Anodontosaurus* was placed in a polytomy with the holotype of *Euoplocephalus* and some specimens that are referred to it, while *Oohkotokia* was placed in a clade with *Dyoplosaurus*, and specimens that are thought to represent either *Dyoplosaurus* or *Scolosaurus*.

## Paleoecology

It lived to the western side of North America, where a huge inland sea provided lots of moisture, and easy accessibility to food for the Euoplocephalus.

## Paleobiology

According to Coombs, *Euoplocephalus* may have had cursorial abilities on par with those of the modern rhinoceros and hippopotamus. Based on the form of the humerus-shoulder articulation and the arrangement of the protracting muscles of the upper arm, it appears that the upper arm sloped away from the body. Coombs and Maryanska (1990) observed that *Euoplocephalus* specimens are usually discovered as isolated elements or partial skeletons, which suggested that this animal engaged in solitary habits and was usually either solitary or participated in small group clusters.

The armor of *Euoplocephalus* may have had a keratinous covering, or it may have floated in the skin, as is seen in modern crocodiles. In addition to protection, the heavily vascularized armor may have had a role in thermoregulation. The palpebral bones over the eyes may have provided additional protection for the eyes. Such bones with *Euoplocephalus* have been discovered in the upper part of the eye socket, instead of in front of the upper socket rim which is the more common position. Coombs explained this by assuming that these bones were located in the eyelid musculature and were probably mobile enough to be moved over the eyes.

## JPInstitute.com Description

Euoplocephalus is the best known of all the armored dinosaurs, which includes Ankylosaurus. This plant-eater was typical of this family of dinosaurs having a low, fat body with a tail ending in a heavy, bony club. It would have wandered in herds throughout the western part of the United States near the end of the age of dinosaurs, munching on low growing plants.

Euoplocephalus was not as heavily armored as some of its family members, but its long tail and heavy club would have made a formidable defensive weapon. The club would have weighed close to 50 pounds (20 kilos) and on the end of a tail that was nearly 7 feet (2 m) long, it would have easily crushed the bones of a large predator.

## Appearance in other media

### *Jurassic Park*

* Euoplocephalus appeared in the video game Jurassic World: Alive.

## Links

http://web.archive.org/web/20040806081436fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_euopl.html#