Hypsilophodon is a very small species of ornithopod dinosaur that lived in the early Cretaceous period in Europe, in England to be exact, and was very similar to the earlier Othnielia and Dryosaurus, which lived only in North America.
Jurassic Park novel
When Gerry Harding captures a "Hypsilophodont" this information is given:
In the harsh quartz lights, the hypsilophodont's green head hung down out of the sling, the tongue dangling, the eyes dull. ... The hypsy was a small dryosaur, seven feet long, weighing about five hundred pounds.
This means that Dryosaurus is the only genus of which we can be sure that it appeared in the first novel.
However, in The Lost World, Hypsilophodon does indeed make a physical appearance; also, the name Dryosaurus is not mentioned in the second novel, meaning the two could potentially be separate genera of dinosaurs. In the book, the Hypsilophodons were living on a marshy plain that was close to the river on the southern side of the island. They are also being described as being dark green with patches of lighter green markings on them as where the dryosaurs were described as being dark green with mottled brown spots.
Jurassic Park video gamesIt appeared in Jurassic Park 2: The Chaos Continues Gameboy version only,
Hypsilophodon appears in the Game Boy Advance game Jurassic Park III: Park Builder.