Name: Achelousaurus

Pronounced: ah-KEL-oo-SORE-us

Meaning: ‘Achelous lizard’ after the Greek river god, Achelous who was a shape-shifter. During a battle with Hercules, Achelous shape-shifted into a bull and Hercules ripped off one of his horns. The three skulls discovered all have rough areas of bone where horns would normally be, giving the impression its horns were torn off.

Period: Late Cretaceous (83 – 70 million years ago)

Group: Ceratopsians (horn faces)

Size: It was 6m long and 2m tall. It weighed approximately 3000kg.

Diet: Herbivore

Characteristics: The Achelousaurus walked on four legs and had an enormous head, with a bird-like beak and giant, bony frills. They also had a large pair of horns protruding from the top of these giant frills. The male frills were notably larger than the females. The skull of a full-grown Achelousaurus, including the frill and horns, has been estimated to be over 1.5 meters long. Palaeontologists have suggested these large head displays could have evolved to scare away predators, attract a mate, keep cool or could simply be a means of identification.

Named by: Scott Sampson in 1995

Discovery: Fossils have been found predominantly in north-western Montana in North America, mainly in the Two Medicine Formation, which crops out to the east of the Rocky Mountain.