Achelousaurus

Achelousaurus is named after the Greek river god Achelous, who could change shape. This name was chosen because the dinosaur has features that seem to be halfway between two other horned dinosaurs, Einiosaurus and Pachyrhinosaurus.1

Adult Achelousaurus had rough, bumpy bosses on their snout and above their eyes instead of the long horns seen in many other horned dinosaurs. These bosses were covered in a thick layer of keratin, the same stuff our fingernails are made of.1

Its skull was about 1.62 metres (5.3 feet) long, which is as long as a tall adult human is tall.1

Achelousaurus lived on an island continent called Laramidia, which was the western part of North America during the Late Cretaceous. The climate was warm and seasonal, with a long dry season.1

The first fossils of Achelousaurus were discovered in 1987 by a team led by famous paleontologist Jack Horner, after he lost access to another fossil site.1

Scientists think Achelousaurus may have used its head bosses for fighting, like bison do today, butting heads with rivals.1

Achelousaurus had a dental battery with 25 to 28 tooth positions in each upper jaw bone. New teeth grew below old ones, so it always had fresh teeth for chewing tough plants.1