Hylaeosaurus
hy-LEE-oh-SORE-us
"woodland lizard"
- Lived
- 139 to 120 million years ago, Early Cretaceous
- Diet
- Herbivore
- Length
- about 5 m (16 ft)
- Group
- Ankylosaurs, Nodosauridae
- Found in
- United Kingdom, Germany and France
- Named by
- Mantell 1833
Size comparison
To scale
Scale in metersOutline: typical ankylosaur shape
Where its fossils were found
The evidence
Today
130 million years ago
Habitat
It lived on low plains crossed by rivers and dotted with lakes in what is now England. Plant eaters in the region included Iguanodon, Barilium and Pelorosaurus.
Field notes
About Hylaeosaurus
What it was like
Hylaeosaurus was an armored plant eater about 5 meters (16 feet) long. It had bony plates along its back and long spines on its shoulders.
Much of its body is still unknown, so scientists are not sure exactly where it fits among the armored dinosaurs.
Its world
It lived about 139 to 120 million years ago, in the Early Cretaceous, in what are now England, Germany and France. Its fossils come from rocks such as the Tunbridge Wells Sand and the Weald Clay.
It shared these lands with Iguanodon, Baryonyx, Polacanthus and Mantellisaurus.
How it was found
Mantell named Hylaeosaurus in 1833, making it one of the first dinosaurs ever named. It was one of the three animals used when the group Dinosauria was first set up, along with Iguanodon and Megalosaurus.
Field gallery
More views of Hylaeosaurus
Scenes reconstructed from the available fossil evidence.
1 of 3
Lived alongside
Found in the same rock formations
A rock formation can hold fossils laid down millions of years apart, so not every animal here met Hylaeosaurus.
The evidence
The science behind Hylaeosaurus
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- The original skeleton preserves parts of the skull, neck, shoulders and ribs, with bony armor around the front of the body.
- The neck spines have thick bases, while the flatter spines farther back sweep toward the rear.
- Scans have identified pieces of the upper jaw, lower jaw and cheek among the crushed skull bones.
Borrowed from relatives
- The missing face and rear of the body are restored by comparison with early armored dinosaurs such as Gargoyleosaurus.
- A tapering tail and compact feet follow other early ankylosaurs.
Still unknown
- The complete arrangement of its armor.
- Its full skull shape and its closest relatives.
- Its color and skin texture.
Often drawn wrong
- Its side spines should not become a tall fence of spikes along the middle of its back.
- Giving it a tail club copies a feature of later armored dinosaurs.
Discovery timeline
- 1833Named itMantell
- 2013New findSachs & Hornung
- 2020RedescriptionRaven et al.
Key papers
The research behind what we know of Hylaeosaurus
Named it
Named an armored plant eater from a partial skeleton with long spines, among the first dinosaurs recognized.
The geology of the south-east of England.
Read the paper : The geology of the south-east of England (opens in a new tab)New find
Compared a German armor spine with Hylaeosaurus and tentatively assigned it and an arm bone to the genus.
Ankylosaur Remains from the Early Cretaceous (Valanginian) of Northwestern Germany. PLoS ONE 8: e60571
Read the paper : Ankylosaur Remains from the Early Cretaceous (Valanginian) of Northwestern Germany (opens in a new tab)Redescription
Restudied the original Hylaeosaurus skeleton and reassessed which other British armored dinosaur finds belong to it.
Osteology and Taxonomy of British Wealden Supergroup (Berriasian–aptian) Ankylosaurs (Ornithischia, Ankylosauria). Journal of Vertebrate Paleontology 40: e1826956
Read the paper : Osteology and Taxonomy of British Wealden Supergroup (Berriasian–aptian) Ankylosaurs (Ornithischia, Ankylosauria) (opens in a new tab)
Close relatives
Other members of Nodosauridae
Sources: Wikidata