Chasmosaurus was a rhinoceros-like dinosaur that was 16-26 feet (5-8 m) long and weighed about 3.5 tons (3220 kg). It had three short horns on its face along with a large bony plate projecting from the back of its skull (a frill). One short, wide horn was on its snout above its parrot-like beak and two backwards-facing brow horns were above its eyes. It had a large skull, four sturdy legs with hoof-like claws, a bulky body and a short, pointed tail. Chasmosaurus hatched from eggs. Its femur (thigh bone) was 75 cm long.
Fossilized Chasmosaurus skin has been found. The skin had knob-like bumps that had 5 or 6 sides.
Chasmosaurus was the most widely distributed Ceratopsian (horned, frilled vegetarians). Many species in this genus have been found, including:
C. belli (Lambe, 1902) [type species] - originally Monoclonius- from Alberta, Canada
C. canadensis (Lambe, 1902) - originally Monoclonius - from Alberta, Canada
C. mariscalensis - Lehman, 1989 - from Texas, USA
C. russelli - Sternberg, 1940 - with no brow horns - from Alberta, Canada
Chasmosaurus was a late Ornithischian dinosaur, the order of bird-hipped, herbivorous dinosaurs. It was a member of the suborder Marginocephalia, and the family of large, horned, herding herbivores, the ceratopsians. The ceratopsians were one of the last major group of dinosaurs to evolve, and include Psittacosaurus, Leptoceratops, Pachyrhinosaurus, Montanoceratops, Chasmosaurus, Centrosaurus, Triceratops, Styracosaurus, Protoceratops, and others.
When Chasmosaurus lived
Chasmosaurus lived in the late Cretaceous period, about 76 to 70 million years ago, toward the end of the Mesozoic, the Age of Reptiles. It was among the last of the dinosaur species to evolve before the Cretaceous-Tertiary extinction 65 million years ago. Among the contemporaries of Chasmosaurus were Tyrannosaurus rex (which probably preyed upon Chasmosaurus), Ankylosaurus (an armored herbivore), Corythosaurus (a crested dinosaur), and Dryptosaurus.
Chasmosaurus was probably a herding animal, like the other ceratopsians (horned, plant-eating dinosaurs). This hypothesis is supported by the finding of bone beds, large deposits of bones of the same species in an area.
Chasmosaurus hatched from eggs which may have been cared for by adults.
When threatened by predators, Chasmosaurus probably charged into its enemy like the modern-day rhinoceros does. This was probably a very effective defense.
Chasmosaurus was a ceratopsian, whose intelligence (as measured by its relative brain to body weight, or EQ) was intermediate among the dinosaurs.
Chasmosaurus was an herbivore, a plant eater. It probably ate cycads, palms, and other prehistoric plants with its tough beak. It could also chew well with its cheek teeth (like other Ceratopsians, but unlike most other dinosaurs).