Temporal range: Late Cretaceous
Dino club
A restoration of Euoplocephalus tutus
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Thyreophora
clade: Dinosauria
Superorder: Thyreophora
Genus: Euoplocephalus
Lambe, 1910
Type species
Euoplocephalus tutus
Lambe, 1902
  • Stereocephalus tutus Lambe, 1902

Euoplocephalus (Greek, "well-armed head") belonged to the ankylosauridae 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.


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) E. tutus. The type species remains S. 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.


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.


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. In the Dinosaur Park Formation it lived alongside the fellow ankylosaurs Anodontosaurus, Dyoplosaurus, Edmontonia, Panoplosaurus, Platypelta, and Scolosaurus. The ceratopsians Chasmosaurus, Centrosaurus, Mercuriceratops, Monoclonius, Spinops, Styracosaurus, Unescoceratops and Vagaceratops. The hadrosaurs Corythosaurus, Gryposaurus, Lambeosaurus, Parasaurolophus and Prosaurolophus. The pachycephalosaurs Foraminacephale, Gravitholus, Hanssuesia, Sphaerotholus, Stegoceras and Microcephale. The ornithomimids Ornithomimus, Qiupalong and Rativates. The oviraptorids Caenagnathus, Chirostenotes and Citipes. The maniraptorans Dromaeosaurus, Hesperonychus, Latenivenatrix, Polyodontosaurus, Richardoestesia, Saurornitholestes and Stenonychosaurus. And the tyrannosaurs Daspletosaurus and Gorgosaurus.


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.

In the Media[]

  • This dinosaur was featured in the Disney movie, Dinosaur, as Earl, a pet which acted like a dog. Of course, this was not meant to be accurate, but for entertainment.
  • Euoplocephalus was a dinosaur featured in the novel, Jurassic Park.
  • Euoplocephalus also appears in the toyline for Jurassic Park III, despite never appearing in the film.
  • It apparently suffered cruelty after the Isla Nublar Incident of 2015 before Jurassic World: Fallen Kingdom. It is unknown if there are any surviving populations.
  • In the PlayStation Game Version of The Lost World: Jurassic Park it was seen as a boss level fighting the Velociraptor.
  • Euoplocephalus appears in a dozen episodes of Dinosaur Train. There's a character named Eugene Euoplocephalus that lives by The Big Pond & is the areas for expert of Dino Ball.
  • Euoplocephalus appears in a dozen episodes & Three Seasons of Dino Dan as a Rare/Common Character.
  • Euoplocephalus Is seen in Dead Sounds Dinosauria Series, digging a shallow pit to rest in.