Chasmosaurus was a Creataceous Period Ceratopsid Dinosaur

Chasmosaurus, pronounced “KAZ-mo-SAWR-us”, is a North American dinosaur that lived during the upper Cretaceous period, about 70-75 million years ago. Its name is from the Greek words meaning “cleft” or “opening” and “lizard”. The name refers to the fenestration in the frill around its neck. It was part of the Ceratopsid family, which is made up of dinosaurs who are primarily characterized by horns and an exclusive taste for plants. It was among the last of the dinosaur species before the Cretaceous-Tertiary extinction, about 65 million years ago.

Quick Facts

What did Chasmosaurus look like?

Chasmosaurus had small and blunt horns compared to other ceratopsians, especially the triceratops. It was a quadruped with a protruding jaw and three horns on its long face. Two forms of Chasmosaurus have had different lengths of the horns found on their faces and it has been suggested that they one was male and the other female. Last but definitely not least, Chasmosaurus had a frill on its neck.

A Collar that was Hard to Miss

Chasmosaurus would have been most recognized visually for the shape of the huge, boxy frill on its neck that spread out, like a canopy made of bone and skin, over its neck and part of its back. Paleontologists suspect that the purpose for it was primarily in mating rituals. It may have even turned different colors during mating season or used as a signal for other members of the herd. It also probably looked threatening to any other dinosaurs that might think to attack. Another theory holds that it functioned as a thermo-regulating device for its body temperature.

Physical Attributes of Chasmosaurus

Chasmosaurus was a frill-necked ceratopsian of intermediate intelligence. Paleontologists can tell intelligence from how large the brain was in proportion to the body. It is evidence that is usually apparent from dinosaur skeletons, assuming both the skull and the body are complete, but paleontologists have discovered other things about Chasmosaurus that they aren’t usually fortunate enough to find with other skeletons. A specimen was discovered that showed impressions of skin. The specimens show regular spaced rows of alternating large and small circular bumps. At up to 20 feet in length and 4 tons in weight, Chasmosaurus was a medium-sized ceratopsian.

What did Chasmosaurus Eat?

Chasmosaurus was a herbivore, so it ate plants. It used its tough beak-like mouth to grab the vegetation and then it chewed with the teeth in the side of its mouth. Other dinosaurs in the Ceratopsid family can do this, but most dinosaurs can’t. Some of the prehistoric plants that were likely part of its diet were cycads, ferns, and palms, but there were probably many more considering that it lived in a wooded region.

How did Chasmosaurus Move?

Chasmosaurus was quadrupedal, which means it walked on its four stout but powerful legs. There is some debate about how fast it moved. Some scientists speculate that ceratopsians, like Chasmosaurus, may have been able to run as fast as rhinos, or up to 35 mph.  It was thought to live in herds, like other ceratopsians. Paleontologists have found bone beds of Chasmosaurus fossils, which are groups of skeletons of the same animal that are found together. Herding indicates the Chasmosaurus had a social disposition and it was helpful for protecting the young or weak members of a species from predators.

Predators of Chasmosaurus

A very famous dinosaur probably preyed on Chasmosaurus, none other than Tyrannosaurus Rex. They both lived at the same time period, during the late Cretaceous era. Chasmosaurus had an intimidating-looking defense against predators, but younger members would have been more vulnerable. The adults probably charged with their horns, like the modern day rhinoceros does, at oncoming threats.

Where did Chasmosaurus Live?

Paleontologists know that Chasmosaurus lived in North America, primarily Canada. The environment was much different than it was today, much warmer and more humid. There were tropical prehistoric plants like cycads and palm trees, but many others that we wouldn’t recognize today. The massive extinction that occurred after Chasmosaurus lived caused over half of the plants to die out.

The Discovery of Chasmosaurus

Chasmosaurus was one of the earliest ceratopsians to be discovered, although it was not known by that name at first. The first part of Chasmosaurus to be discovered was its distinctive neck frill. Lawrence M. Lambe of the Geological Survey of Canada discovered it in 1898. At first, he assigned the neck frill to another dinosaur from the Ceratopsid suborder and he named the new species Monoclonius belli. Finally, in 1914 it was correctly renamed, after Charles Sternberg and his sons found several more skulls of the same species in Alberta, Canada. More Chasmosaurus fossils have been found since that date, although there is some variation among the bones, such as different sized horns. They have been classified as different species, but there is some speculation that they are different genders of the same species.

The Importance of Chasmosaurus

Chasmosaurus is important because it was one of the last dinosaurs to have evolved before the great extinction that occurred about 65 million years ago. It is sometimes called the K-T extinction, K stands for kreide, which is German for chalk and describes the chalky sediment of the environment at the time. T stands for tertiary, which is the name for the next period. All land animals over 55 pounds, and some smaller organisms, went extinct. Chasmosaurus and its contemporaries were the last stage in development of an animal that was once very abundant.