- Means "helmet lizard"
- Had a hollow, bony crest on top of its long head in the shape of a helmet flattened on the sides
- Had duck-like bill, a toothless beak and hundreds of cheek teeth that it used to grind up its food
- Lived during the late Cretaceous period, about 80 to 65 million years ago
- Walked and ran on two legs, and was a relatively fast dinosaur. It may have gone on all fours to forage for low-lying plants
- Had shorter arms, and a long, heavy tail
- Spent much time in the water
- Had no natural defenses
- Was named by Barnum Brown in 1914 from a fossil found in Alberta, Canada
- Fossils have been found in North America, including Montana, USA, and Alberta, Canada
- Diet: Herbivore (plant-eater), perhaps eating pine needles, conifers, ginkgos, seeds, cycads, twigs, and magnolia leaves.
- Average life span: 65 years
- Height: 6.6 ft tall at the hips
- Length: 30-33 ft
- Weight: 4 or 5 tons (about as heavy as an elephant)