Chasmosaurus fossil map
Where fossils of Chasmosaurus have been found, shown on the Earth as it looked about 75 million years ago and on today’s map.
Dots are fossil collections recorded in the Paleobiology Database. The “then” view moves today’s fossil sites back to their positions 75 million years ago (the time slice nearest the median age of the fossils) using the Merdith et al. (2021) plate model; positions are approximate. Open on the timeline map →
| Group | Horned & dome-headed dinosaurs |
|---|---|
| Lived | 83.6–72.2 million years ago (Campanian) |
| Periods | Cretaceous |
| Family | Ceratopsidae |
| Named by | Lambe 1914 |
| Fossil records | 21 occurrences at 21 locations (PBDB) |
| Found in | Canada, United States |
| Rock formations | Dinosaur Park, Oldman, Judith River, txn:38851 |
About Chasmosaurus
Chasmosaurus ( KAZ-moh-SOR-əs) is a genus of ceratopsid dinosaur from the Late Cretaceous Period in North America. Its given name means 'opening lizard', referring to the large openings (fenestrae) in its frill (Greek chasma, meaning 'opening', 'hollow', or 'gulf'; and sauros, meaning 'lizard'). With a length of 4.3–4.8 metres (14.1–15.7 ft) and a weight of 1.5–2 tonnes (1.7–2.2 short tons)—or anywhere from 2,200 to nearly 5,000 lbs—Chasmosaurus was of a slightly smaller to "average" size, especially when compared to larger ceratopsids (such as Triceratops, which were about the size of an African bush elephant).
It was initially to be called Protorosaurus, but this name had been previously published for another animal. All of the excavated specimens of Chasmosaurus were collected at the Dinosaur Park Formation, Dinosaur Provincial Park, Alberta, Canada. For many years, Chasmosaurus russelli was considered a second species. However, in 2026 its type specimen was given the separate genus Cryptarcus, with other prior "C. russelli" specimens being of uncertain taxonomy.
Text in “About” is quoted from the Wikipedia article Chasmosaurus (revision 1374377095), licensed under CC BY-SA 4.0; introduction excerpted verbatim, formatting removed. Ages, family, authority and fossil records: Paleobiology Database, accessed 22 October 2026. Ages are those of the rock layers the fossils were found in. Wikidata: Q131586.
