A “woodland (Wealden) lizard” from Late (or Early) Cretaceous southeast England.

It was named for the lower Cretaceous Wealden deposit at Tilgate Forest. In an 1832 presentation before the Geological Society, Mantell originally explained the name as “forest lizard”, alluding to Tilgate Forest where the first specimen was unearthed; however, in later published works he gave the meaning as “Wealden lizard”, establishing the use of hylaeo- as a kind of pun in 19th century paleontology for the geological term “Wealden” (Hylaeochampsa Owen “Wealden crocodile”, Hylaeochelys Lydekker “Wealden turtle”,etc.).

The British geologist, Peter Martin, invented the name “Wealden” in 1828 for the Early Cretaceous sands and clays found in the once-forested Weald (“wood”) region of southern England. This creature was previously known as Polacanthus. Named by British paleontologist Gideon A. Matheron Mantell (1790-1852) in 1833.