Hylaeosaurus was a plant-eating dinosaur from the late Valanginian stage of the Lower Cretaceous era of England. Its name is Greek for “belonging to the forest” and is one of the first-ever dinosaurs to be discovered in 1832 by paleontologist Gideon Mantell. Only a handful of fossils have been discovered for the Hylaeosaurus, hence a lot of its autonomy remains unknown. 

Key Facts

Hylaeosaurus pronunciationHIGH-lee-oh-sore-us
What does Hylaeosaurus mean?Woodland lizard
Dinosaur typeArmoured
On the menuHerbivorous
Length16 feet (5 meters)
Height7 feet (2 meters)
WeightAbout 4000 lbs (1.8 tons)
Life expectancyUnknown
Legs used to get aroundQuadruped
Estimated top speedUnknown
When they livedLower Cretaceous era 150-135 million years ago
Where they have been found?England, United Kingdom

When & Where

The discovery of Hylaeosaurus fossils took place in England in 1832, and the skeleton was first described in 1842 by Richard Owen. It is one of the most complete dinosaur skeletons ever found, with over 130 bones recovered. The genus name comes from the Greek words for “woodland” and “lizard.”

Size & Weight

They were about 5 meters (16 feet) long and weighed nearly 2 tons (about 4,000lbs). No new fossils have ever been found since its discovery in 1832, so there is limited knowledge concerning its exact length and body mass. 

Mobility & Diet

The diet of Hylaeosaurus consisted primarily of ferns, conifers, and cycads, though they also ate small mammals trapped in bushes and tree branches. Hylaeosaurus was able to jump short distances, but it probably did not run very fast because it had short legs compared to other dinosaurs. It may have been able to swim or float on water by flipping its body over so only its head and tail were exposed to the water. 

Interesting Points

  • The main threat the Hylaeosaurus faced was competition for resources with other larger dinosaurs, such as the Tyrannosaurus Rex
  • It was one of the trio dinosaurs named Dinosauria in 1842 by Sir Richard Owen. 
  • Since its discovery in 1842, no new fossil remains have been found to date.

Featured Image Credit: Benjamin Waterhouse Hawkins, Public domain, via Wikimedia Commons