Hypsilophodon foxii

Hypsilophodon foxii. Artist: Kate Nolan. Source: Museum Victoria.

The Hypsilophodont family appeared early in the history of dinosaurs and persisted until the extinction of the entire group 65 million years ago. They were small fast running herbivorous dinosaurs, related to the larger hadrosaurs and ceratopsians. Hypsilophodont fossils are known from every continent, but are generally quite rare. Victoria is unusual in this regard, as more than half its known dinosaur fossils are hypsilophodonts.

Hypsilophodonts had a number of distinctive features:

• They stood on their hind legs, which were twice as long as their front legs.
• Their tails accounted for half their body length, and were stiffened by bony tendons, presumably so that they could be held above the ground while running.
• Their hind feet were four-toed, while their 'hands' were five-fingered.
• Their heads were small with beak-like jaws. Some hypsilophodonts, like the recently discovered Qantassaurus, had heavy jaws, but others were much more gracile.
• They had broad chisel-like teeth that formed a continuous cutting edge, and cheek pouches where food was stored for a short time while it was chewed.

The hypsilophodont exhibited at Melbourne Museum is a cast of a fossil skeleton of Hypsilophodon foxii from England, the species after which the family was named.