Hypsilophodon
hip-suh-LOF-oh-don
- Lived
- 149 to 101 million years ago, Late Jurassic to Early Cretaceous
- Diet
- Herbivore
- Length
- about 2.3 m (8 ft)
- Group
- Ornithopods, Hypsilophodontidae
- Found in
- United Kingdom, Japan, Portugal and Romania
- Named by
- Huxley 1870
Size comparison
To scale
Scale in meters
Where its fossils were found
The evidence
Today
125 million years ago
Habitat
The Wessex floodplain in England developed into marsh and lagoon-edge mudflats. Regional dinosaurs included Iguanodon, Polacanthus and Neovenator.
Field notes
About Hypsilophodon
What it was like
Hypsilophodon was a small, fast-moving plant eater that ran on two long legs. It grew to about 2.3 meters (7.5 feet) long, with a stiff tail held out for balance and a beak-tipped snout for cropping low plants. Its light, narrow build suggests it relied on speed rather than size to escape predators.
Its world
Hypsilophodon lived across what are now the United Kingdom, Portugal, Japan, and Romania, from the Late Jurassic into the Early Cretaceous, between about 149 and 101 million years ago. Its bones come from formations including Wessex, Vectis, and Lourinhã, from seven finds in total.
In the United Kingdom, it lived alongside larger dinosaurs such as Iguanodon, Baryonyx, and the armored Polacanthus, as well as predators including Megalosaurus and Allosaurus.
How it was found
Huxley named Hypsilophodon in 1870. It is the namesake of Hypsilophodontidae, a family of small, fast-moving ornithopods related to Vectidromeus and Gideonmantellia. With seven finds across several countries, Hypsilophodon is one of the better-known early ornithopods, though scientists still debate exactly how it fits among other ornithischians.
Field gallery
More views of Hypsilophodon
Scenes reconstructed from the available fossil evidence.
1 of 7
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 Hypsilophodon.
The evidence
The science behind Hypsilophodon
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- Many skeletons preserve a small plant eater with long hindlegs and a tail stiffened by bony tendons.
- Skulls show a beak at the snout tip and teeth for processing plants.
- The hands had five fingers, and the feet were built for moving on the ground.
Borrowed from relatives
- Almost the whole skeleton is known from its own bones.
- Scaly skin follows comparison with other ornithopods; Vectidromeus helps show how its skeleton differs from a close relative.
Still unknown
- Its skin color and the details of its body covering.
- Whether it regularly lived in groups.
- How adults behaved toward their young.
Often drawn wrong
- Older pictures put it in trees, but its limbs and feet belonged to a ground runner.
- A drooping tail misses the stiff support provided by bony tendons.
Discovery timeline
- 1870Named itHuxley
- 1971PostureGALTON
- 1974Full descriptionGalton
- 2024Close relativeLongrich et al.
- 2024Its worldMarsden et al.
Key papers
The research behind what we know of Hypsilophodon
Named it
Recognized Hypsilophodon as a distinct small plant-eating dinosaur from England.
On Hypsilophodon Foxii , a new Dinosaurian from the Wealden of the Isle of Wight. Quarterly Journal of the Geological Society of London 26: 3-12
Read the paper : On Hypsilophodon Foxii , a new Dinosaurian from the Wealden of the Isle of Wight (opens in a new tab)Posture
Reexamined the limbs and feet and concluded that Hypsilophodon ran on the ground rather than climbing trees.
Hypsilophodon, the Cursorial Non-arboreal Dinosaur. Nature 231: 159-161
Read the paper : Hypsilophodon, the Cursorial Non-arboreal Dinosaur (opens in a new tab)Full description
Described the skull and skeleton in detail, providing the foundation for understanding its anatomy.
The ornithischian Dinosaur Hypsilophodon from the Wealden of the isle of Wight. Bulletin of the British Museum (Natural History) Geology 25: 1-152
Read the paper : The ornithischian Dinosaur Hypsilophodon from the Wealden of the isle of Wight (opens in a new tab)Close relative
Described Vectidromeus and compared its bones with adult and young Hypsilophodon, identifying differences between the close relatives.
Vectidromeus insularis, a new hypsilophodontid dinosaur from the Lower Cretaceous Wessex Formation of the Isle of Wight, England. Cretaceous Research 154: 105707
Read the paper : Vectidromeus insularis, a new hypsilophodontid dinosaur from the Lower Cretaceous Wessex Formation of the Isle of Wight, England (opens in a new tab)Its world
Reconstructed a floodplain that became marsh and lagoon-edge mudflats, and found that the fossil remains accumulated over time.
Palaeoenvironment and taphonomy of the Hypsilophodon Bed, Lower Cretaceous Wessex Formation, Isle of Wight. Journal of the Geological Society 182
Read the paper : Palaeoenvironment and taphonomy of the Hypsilophodon Bed, Lower Cretaceous Wessex Formation, Isle of Wight (opens in a new tab)
Close relatives
Other members of Hypsilophodontidae
Sources: Wikidata