Temporal range: Late Cretaceous
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Order: Ornithischia
Family: Ankylosauridae
Subfamily: †Ankylosaurinae
Tribe: †Ankylosaurini
Genus: Ankylosaurus
Brown, 1908
Species: A. magniventris
Binomial name
Ankylosaurus magniventris
Brown, 1908
Ankylosaurus JW concept art.png

Ankylosaurus is an extinct genus of ankylosaur that lived in North America during the Late Cretaceous period. It was the size of an elephant. It lived alongside carnivores such as Tyrannosaurus rex but like all ankylosaurs it was not in any danger from them due to its armored back - which no carnivore would be able to bite through - and a tail club, which could mortally injure a T. rex or any carnivore.


Compared with modern land animals the adult Ankylosaurus was very large. Some scientists have estimated a length of 11 meters (36 feet).[1] Another reconstruction suggests a much smaller size, at 6.25 meters (20.5 feet) long, up to 1.5 meters (5 feet) wide and about 1.7 meters (5.5 feet) high at the hip.[2] Ankylosaurus may have weighed over 6,000 kilograms (13,000 lbs),[3] making it one of the heaviest armored dinosaurs yet discovered. The body shape was low-slung and quite wide. It was quadrupedal, with the hind limbs longer than the forelimbs. Although its feet are still unknown, comparisons with other ankylosaurids suggest Ankylosaurus probably had five toes on each foot. The skull was low and triangular in shape, wider than it was long. The largest known skull measures 64.5 centimeters (25 inches) long and 74.5 cm (29 inches) wide.[4] Their teeth were weaker than ceratopsid and hadrosaurid dinosaurs of the time, so they probably chewed very little.


The armor of Ankylosaurus was made of huge knobs and plates of bone, known as osteoderms or scutes, embedded in the skin. Osteoderms are also found in the skin of crocodiles, armadillos and some lizards. The bone may have been covered by a tough, horny layer of keratin. These osteoderms ranged in size, from wide, flat plates to small, round nodules. The plates were lined up in regular horizontal rows down the animal's neck, back, and hips, with the many smaller nodules protecting the areas between the large plates. Smaller plates may have been on the limbs and tail. Compared to the slightly more ancient ankylosaurid Euoplocephalus, the plates of Ankylosaurus were smooth in texture, without the high keels found on the armor of the coexisting nodosaurid Edmontonia. A row of flat, triangular spikes may have stuck out sideways along each side of the tail. Tough, rounded scales protected the top of the skull, while four horns were behind the eyes and the ends of the mouth.[5]

Tail club

Classification Ankylosaurus was named as the type genus of the family Ankylosauridae.[6] Ankylosaurids are members of the larger taxon Ankylosauria, which also contains the nodosaurids. Ankylosaur phylogeny is a heated topic, with several mutually exclusive studies given in recent years, so the exact position of Ankylosaurus within Ankylosauridae is unknown. Ankylosaurus and Euoplocephalus are often thought to be sister taxa.[1] However, other studies have found these genera in different positions.[7][8] Further discoveries or research may clear up the situation.


Ankylosaurus was named by American paleontologist Barnum Brown, in 1908. The name comes from the Greek words αγκυλος/ankulos ('curved') and σαυρος/sauros ('lizard'). Brown intended this name in the same sense as the medical term ankylosis, to refer to the stiffness  from the fusion of many bones in the skull and body, so the name is often translated as 'stiffened lizard.' The type species is A. magniventris, from the Latin magnus ('great') and venter ('belly'), referring to the great width of the animal's body.[6]


Ankylosaurus magniventris lived between 68 - 66.5 million years ago, in the final Maastrichtian stage of the Late Cretaceous Period, and was one of the last dinosaur species that appeared before the Cretaceous-Tertiary extinction event. The type specimen is from the Hell Creek Formation of Montana, while other specimens have been found in the Lance Formation of Wyoming and the Scollard Formation in Alberta, Canada, all of which date to the end of the Cretaceous.[1]

The Lance, Hell Creek and Scollard Formations represent different sections of the western shore of the shallow that divided western and eastern North America during the Cretaceous. They represent a broad coastal plain, extending westward from the seaway to the newly formed Rocky Mountains. These formations are composed largely of sandstone and mudstone, which have been attributed to floodplain environments.[9][10][11] The Hell Creek is the best studied of these ancient environments. At the time, this region was subtropical, with a warm and humid climate. Many plant species were supported, primarily angiosperms, with less common conifers, ferns and cycads. An abundance of fossil leaves found at dozens of different sites indicates that the area was largely forested by small trees.[12] Ankylosaurus shared its environment with dinosaurs including the ceratopsids Triceratops and Torosaurus, hypsilophodont Thescelosaurus, hadrosaurid Edmontosaurus, nodosaurid Edmontonia, pachycephalosaurian Pachycephalosaurus, and the theropods Ornithomimus, Troodon, and Tyrannosaurus.[13][14]

Fossils of Ankylosaurus are quite rare in these grounds, compared to Edmontosaurus and the super-abundant Triceratops, which make up most of the large herbivore fauna. Another ankylosaur, Edmontonia, is also found in the same formations. However, Ankylosaurus and Edmontonia seem to have been separated both geographically and ecologically. Ankylosaurus had a wide muzzle, perhaps used for non-selective grazing and thus may have been limited to the upland regions, away from the coast, while Edmontonia had a narrower muzzle, indicating a more selective diet, and seems to have lived at lower elevations, closer to the coast.[2]


Ankylosaurus once inhabited the woods, felids, lowlands, grasslands, forests, meadows, plains and the valleys of Montana, North Dakota, South Dakota, Wyoming and Alberta around the Late Cretaceous and a little bit into the Early Paleogene. Dinosaurs that were found in the locations that Ankylosaurus inhabited they shared the same habitat with the armored dinosaur. The wetlands Ankylosaurus and other dinosaurs lived was filled with grass, trees, brooks, streams, creeks, ponds, woodlands, shrubs and ferns.

Lance Formation

Around the time of the Cretaceous period the Lance Formation was a floodplain filled with streams, brooks, creeks, woods, frests, feilds and meadows. It was a place that once had ponds, shrubs, ferns, trees and grass. There were also other animals that called the place their home along with Ankylosaurus and the dinosaurs who lived there. Animals that inhabited Lance Formation were amphibians like, frogs, toads, salamanders, reptiles like, turtles, alligators, crocodiles, snakes, lizards, fish, invertebrates like, arthropods, arachnids, insects, crustaceans, birds and small mammals.

Scollard Formation

The Scollard Formation was a floodplain near Scollard Canyon Alberta, Canada. Ankylosaurus made this place it's home which was made up of feilds, meadows, woods, forests, ponds, streams, brooks and creeks. The formation had trees, shrubs and ferns growing in the plain. These floodplains were not only home to Ankylosaurus and other dinosaurs but it was also home to reptiles like, lizards, snakes, alligators, crocodiles, amphibians like, salamanders, toads, frogs, invertebrates like, crustaceans, insects, arachnids, arthropods, as well as birds, small mammals and fish.

Hell Creek Formation

It's believed that Hell Creek was a floodplain during the late cretaceous period. This formation was home to Ankylosaurus and a huge number of many different dinosaurs. Animals such as amphibians like, frogs, toads, salamanders, reptiles like, turtles, snakes, crocodiles, alligators, birds, small mammals, invertebrates like, crustaceans, insects, arachnids, arthropods, and fish like, freshwater rays, freshwater sharks. Hell Creek was a lowland with woods, streams, ponds, creeks, forests, brooks, shrubs, ferns and grasslands.

Red Deer River

In the media

  • Ankylosaurus was shown in Walking with Dinosaurs in Episode 6, Death of a Dynasty, where it injures a mother T-rex with its' club.
  • It will be in the upcoming game Saurian as a playble dinosaur.
  • Ankylosaurus makes various appearances in the The Land Before Time series. However, they are referred to as “club-tails” by the main characters and the other species of dinosaurs featured in the series.
  • Ankylosaurus appeared in both Power Rangers Dino Thunder and Power Rangers Dino Charge.
  • Anguirus from the Godzilla series is based on Ankylosaurus.
  • A baby Ankylosaurus served as a main character in the Japanese book and animated film You Are Umasou.
  • Ankylosaurus had a brief cameo in Fantasia.
  • Ankylosaurus also appears three times in Dinosaur Train. There's a character named Hank Ankylosaurus, the best dino ball player.
  • Ankylosaurus makes it's appearance in Dino Hunter: Deadly Shores as the Trophy Hunt dinosaur "Bastion".
  • Ankylosaurus is one of the creatures players can encounter in the videogame ARK: Survival Evolved in which players have to survive on an island filled with prehistoric creatures. In this game, Ankylosaurus is one of the many creatures tameable by players. It can even be ridden when provided with the right saddle.
  • Ankylosaurus appeared in the video game Jurassic World: Evolution.
  • Ankylosaurus appeared in the 2011 Science Fiction Show Terra Nova.
  • Ankylosaurus appeared in Jurassic World: Camp Cretaceous where a baby that grows into a teenager is named Bumpy.
  • Ankylosaurus appears in the game Jurassic World Alive.




  1. 1.0 1.1 1.2 Vickaryous, M.K., Maryanska, T., & Weishampel, D.B. 2004. Ankylosauria. In: Weishampel, D.B., Dodson, P., & Osmólska, H. (Eds.). The Dinosauria (2nd edition). Berkeley: University of California Press. Pp. 363-392.
  2. 2.0 2.1 Carpenter, K. 2004. Redescription of Ankylosaurus magniventris Brown 1908 (Ankylosauridae) from the Upper Cretaceous of the Western Interior of North America. Canadian Journal of Earth Sciences 41: 961–986.
  3. Coombs, Walter P. (December 1978). "Theoretical Aspects of Cursorial Adaptations in Dinosaurs". The Quarterly Review of Biology 53 (4): 393–418. doi:10.1086/410790.
  4. Carpenter, K. 2004. Redescription of Ankylosaurus magniventris Brown 1908 (Ankylosauridae) from the Upper Cretaceous of the Western Interior of North America. Canadian Journal of Earth Sciences 41: 961–986
  5. Carpenter K. 2004. Redescription of Ankylosaurus magniventris Brown 1908 (Ankylosauridae) from the Upper Cretaceous of the Western Interior of North America. Canadian Journal of Earth Sciences, 41: 961–986.
  6. 6.0 6.1 Brown, B. 1908. The Ankylosauridae, a new family of armored dinosaurs from the Upper Cretaceous. Bulletin of the American Museum of Natural History 24: 187–201.
  7. Carpenter, K. 2001. Phylogenetic analysis of the Ankylosauria. In: Carpenter, K. (Ed.). The Armored Dinosaurs. Bloomington: Indiana University Press. Pp. 454–483.
  8. Hill, R.V., Witmer, L.M., & Norell, M.A. 2003. A new specimen of Pinacosaurus grangeri (Dinosauria: Ornithischia) from the Late Cretaceous of Mongolia: ontogeny and phylogeny of ankylosaurs. American Museum Novitates 3395: 1-29.
  9. Lofgren, D.F. 1997. Hell Creek Formation. In: Currie, P.J. & Padian, K. (Eds.). The Encyclopedia of Dinosaurs. San Diego: Academic Press. Pp. 302-303.
  10. Breithaupt, B.H. 1997. Lance Formation. In: Currie, P.J. & Padian, K. (Eds.). The Encyclopedia of Dinosaurs. San Diego: Academic Press. Pp. 394-395.
  11. Eberth, D.A. 1997. Edmonton Group. In: Currie, P.J. & Padian, K. (Eds.). The Encyclopedia of Dinosaurs. San Diego: Academic Press. Pp. 199-204.
  12. Johnson, K.R. 1997. Hell Creek Flora. In: Currie, P.J. & Padian, K. (Eds.). The Encyclopedia of Dinosaurs. San Diego: Academic Press. Pp. 300-302.
  13. Weishampel, David B.; Barrett, Paul M.; Coria, Rodolfo A.; Le Loeuff, Jean; Xu Xing; Zhao Xijin; Sahni, Ashok; Gomani, Elizabeth, M.P.; and Noto, Christopher R. (2004). "Dinosaur Distribution". The Dinosauria (2nd). 517–606.
  14. Phillip Bigelow. "Cretaceous "Hell Creek Faunal Facies"; Late Maastrichtian". http://www.scn.org/~bh162/hellcreek2.html. Retrieved 2007-01-26.