“The Armored Tank of Hell Creek”
Binomial Ankylosaurus magniventris · ANG-kee-loh-SOR-us
Late Cretaceous · 68-66 Ma
IllustrationAnkylosaurus fossil records in Fossil Atlas are mapped as selected modern discovery locations, with 31 source-backed records currently shown. Known from latest Cretaceous records in western North America, including Hell Creek and related northern Great Plains units. Key mapped formations in the current dataset include Belly River (Judith River) Group, Ferris Fm., Kirtland Formation. These pins are fossil record locations, not a complete ancient habitat map.
Ankylosaurus was a large armored dinosaur from latest Cretaceous North America. Its fossil record includes armor, skull material, and the famous tail club, though complete skeletons are rare. Fossil Atlas uses selected records to connect it to Hell Creek and related northern Great Plains units.
Drawn true to scale on a metre ruler.
Length
measured7.5 m · 25 ft
Largest known specimens
Height
measured1.7 m · 5.5 ft
Body mass
estimate6,000 kg · 13,200 lb
Typical adult
Top speed
estimate10 km/h · 6 mph
Modelled, debated
Brain : body (EQ)
estimate0.7
Encephalization quotient
Ankylosaurus was the largest known ankylosaur and the most heavily armored herbivore in the Hell Creek ecosystem. It browsed low vegetation with its small teeth and beak, relying on passive armor and an active tail club for defense rather than speed or group behavior. The tail club was heavy enough to break bone, and given that T. rex was its main contemporary predator, that capability was not incidental.
The armor
Bony plates called osteoderms covered the back, sides, and much of the neck. The combination of size, low center of gravity, and continuous plating made it difficult to attack from above or the sides.
The tail club
A solid mass of fused bone at the tail tip, capable of swinging with considerable force. At least one T. rex specimen preserves injuries consistent with a heavy blow from a large object.
Build
Low-slung and very wide, making it hard to flip. The posture kept the most vulnerable underside close to the ground.
Feeding
Small leaf-shaped teeth and a beak suggest it ate low-growing plants. Ankylosaurus was not a high browser.
Position of this animal’s known range across 252 million years of the Mesozoic and beyond.
68-66 million years ago
Ankylosaurus carried a bony club at the end of its tail.
Its body armor makes its silhouette ideal for expedition cards.
It lived near the end of the age of dinosaurs.
Ankylosaurus adds a low, armored herbivore to the Hell Creek cluster.
Barnum Brown collected the first Ankylosaurus material from the Hell Creek Formation in 1906 and named it the same year. Complete skeletons are rare: most of what is known comes from skull fragments, armor, and the tail club. Related ankylosaurs, particularly Euoplocephalus from slightly earlier Canadian deposits, are better represented and often used to fill in anatomical details that Ankylosaurus specimens do not preserve.
Animals known from the same deposits and time as Ankylosaurus.
Tyrannosaurus rex
The only predator in the Hell Creek ecosystem large enough to pose a serious threat to an adult Ankylosaurus.
Triceratops
The dominant horned herbivore sharing the same latest Cretaceous landscapes.
Edmontosaurus
A large duck-billed herbivore from the same formation, occupying a very different ecological niche.
Other members of Ankylosauridae.
Euoplocephalus
A well-known Canadian ankylosaur from the slightly earlier Dinosaur Park Formation, better represented in the record and often used to understand Ankylosaurus anatomy.
Nodosaurus
A nodosaurid from earlier Cretaceous North America, lacking a tail club, showing the diversity within the armored dinosaur group.
Gastonia
An Early Cretaceous ankylosaur from Utah's Cedar Mountain Formation, covered in lateral spikes.
Pins show selected fossil records for Ankylosaurus; use them as modern discovery evidence, not a complete range map. Modern fossil discovery map: pins show where selected fossil and specimen records were found today, not ancient Earth positions. What does this mean?
Specimen evidence
These are sourced specimen assets, separate from reconstruction artwork. Only media with clear open or reusable rights is displayed by default.
USNM V 7954_1
Michael Brett-Surman
USNM V 7724_1
Michael Brett-Surman
Ankylosaurus is represented here by selected fossil records from known from latest cretaceous records in western north america, including hell creek and related northern great plains units. Fossil Atlas maps those records as modern discovery locations.
No. The map shows modern fossil discovery locations from selected records. Ancient habitat and paleogeographic reconstructions are separate questions.
The current Fossil Atlas records include Belly River (Judith River) Group. Formation coverage depends on the selected dataset and may not be complete.
Yes. Use the expedition card generator to turn the Ankylosaurus map and specimen profile into a shareable card.
Selected fossil records from PBDB and museum biodiversity aggregators. This is not a complete fossil count by country; source labels and confidence notes help distinguish canonical paleobiology records from specimen-media records.
Reconstruction images are labeled illustrations and do not represent fossil evidence. Size, speed, and bite-force figures are typical published estimates and remain subject to revision as new specimens are described.
Maps use curated PBDB, museum, and specimen-source records with visible caveats.
Pins show where fossils were found or reported today, not exact ancient habitat positions.
Artwork is labeled separately from specimen photos, maps, and source records.
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