Chasmosaurus

chasmosaurus
Chasmosaurus (Royal Tyrrell Museum).

Name:

Chasmosaurus (Greek for "cleft lizard"); pronounced KAZZ-moe-SORE-us

Habitat:

Woodlands of western North America

Historical Period:

Late Cretaceous (75-70 million years ago)

Size and Weight:

About 15 feet long and 2 tons

Diet:

Plants

Distinguishing Characteristics:

Huge, rectangular frill on neck; small horns on face

 

About Chasmosaurus

A close relative of Centrosaurus, and thus classified as a "centrosaurine" ceratopsian, Chasmosaurus was distinguished by the shape of its frill, which spread out over its head in an enormous rectangle.

Paleontologists speculate that this giant awning of bone and skin was lined with blood vessels that allowed it to take on bright colors during mating season, and that it was used to signal availability to the opposite sex (and possibly to communicate with other members of the herd).

Perhaps because the addition of horns would have been simply too much (even for the Mesozoic Era), Chasmosaurus possessed relatively short, blunt horns for a ceratopsian, certainly nothing approaching the dangerous apparatus of Triceratops. This may have something to do with the fact that Chasmosaurus shared its North American habitat with that other famous ceratopsian, Centrosaurus, which sported a smaller frill and a single large horn on its brow; the difference in ornamentation would have made it easier for two competing herds to steer clear of each other.

By the way, Chasmosaurus was one of the first ceratopsians ever to be discovered, by the famous paleontologist Lawrence M. Lambe in 1898 (the genus itself was later "diagnosed," on the basis of additional fossil remains, by Charles R.

Sternberg). The next few decades witnessed a bewildering multiplication of Chasmosaurus species (not an unusual situation with ceratopsians, which tend to resemble one another and can be difficult to distinguish at the genus and species level); today, all that remain are Chasmosaurus belli and Chasmosaurus russelli.

Recently, paleontologists discovered the amazingly well-preserved fossil of a Chasmosaurus juvenile in Alberta's Dinosaur Provincial Park, in sediments dating to about 72 million years ago. The dinosaur was about three years old when it died (most likely drowned in a flash flood), and lacks only its front legs.