Pronunciation: KAS-mo-SOR-us Meaning: Chasm lizard Author/s: Lambe (1922) Synonyms: Protorosaurus First Discovery: Alberta, Canada Chart Position: 81
When Lawrence Lambe ran the rule over what would eventually become Chasmosaurus, he added it to the fossil register as Monoclonius belli; a second species of E.D. Cope's Monoclonius, but the discovery of similar yet more complete remains by Sternberg and sons during the early part of the 20th century convinced him that his new ceratopsian wasn't Monoclonius at all. In 1914, Lambe decided on a replacement name—Protorosaurus—blissfully unaware that Christian von Meyer had already assigned it to the earliest known archosauromorph (Protorosaurus speneri) some 84 years earlier. So, he settled on Chasmosaurus belli—Bell's Chasm lizard—later the same year, in honor of its discoverer John Hatcher Bell and for the wide openings in an ornate bony frill that protruded from the rear of its skull.
EtymologyChasmosaurus is derived from the Greek "khasma" (wide opening/chasm/cleft) and "sauros" (lizard), named for the huge openings (fenestrae) in its frill.
The species epithet (or specific name), belli, honors Dr. Robert Bell, the then-administrative head of the Geological Survey of Canada.
DiscoveryThe first fossils of Chasmosaurus were discovered in the Dinosaur Park Formation at Berrt Creek, Dinosaur Provincial Park, Alberta, Canada by Lawrence Lambe in 1898.
The holotype (NMC 491) is part of a neck frill.
In 2011, a chasmosaurine skull that William Cutler excavated from Alberta's Dinosaur Park Formation in 1919–1920 was referred to Chasmosaurus belli. Although almost complete, it was found in bits, which allowed the inside of a chasmosaurine skull to be examined in detail for the first time.