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Chasmosaurus, Late CretaceousDinosaur Park Formation, Alberta · named 1914
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Chasmosaurus

KAZ-moh-SORE-us

"opening lizard"

Lived
84 to 72 million years ago, Late Cretaceous
Diet
Herbivore
Length
about 5 m (16 ft)
Group
Ceratopsians, Ceratopsidae
Found in
Canada
Named by
Lambe 1914

Size comparison

To scale

Where its fossils were found

The evidence

Today

19 finds

80 million years ago

Map: C. R. Scotese, PALEOMAP

Habitat

Rivers crossed the low floodplains of Alberta, with forests and fern-covered ground. Regional neighbors included Centrosaurus, Corythosaurus and Gorgosaurus.

Field notes

About Chasmosaurus

What it was like

Chasmosaurus was a horned dinosaur that grew to about 5 meters (16 feet) long, with a long, bony frill extending back from its skull. Unlike some relatives, its frill had two large openings in it, which gave the genus its name and likely made the structure lighter without weakening it much. Chasmosaurus carried a pair of horns above its eyes and a shorter horn on its nose, and moved on four sturdy legs while cropping low plants with its beaked mouth.

Its world

Chasmosaurus lived in Alberta, Canada, from about 84 to 72 million years ago, sharing its floodplain habitat with fellow horned dinosaurs such as Centrosaurus and with hadrosaurs like Lambeosaurus and Corythosaurus. Predators including Gorgosaurus and Daspletosaurus hunted across the same ground, while smaller theropods such as Troodon and Dromaeosaurus likely targeted young or weakened animals.

How it was found

Lambe named Chasmosaurus in 1914, and its remains have since turned up in about 19 separate fossil finds, all from the Dinosaur Park and Oldman formations of Alberta. It is closely related to larger horned dinosaurs such as Triceratops and Torosaurus.

Field gallery

More views of Chasmosaurus

Scenes reconstructed from the available fossil evidence.

Chasmosaurus in its habitat, photo 1

1 of 7

Lived alongside

Found in the same rock formations

A rock formation can hold fossils laid down millions of years apart, so not every animal here met Chasmosaurus.

The evidence

The science behind Chasmosaurus

Which parts of the picture come from its own bones, and which come from its relatives.

From its own fossils

  • Skulls show a long, broad frill with large openings in the bone and horns over the eyes and nose.
  • An articulated juvenile skeleton preserves a short, narrow frill and skin impressions.
  • Adult skulls show variation in the outline and ornament of the frill.

Borrowed from relatives

  • Much of the body is known from its own bones.
  • The outer horn covering is reconstructed by comparison with other horned dinosaurs such as Triceratops.

Still unknown

  • Its frill color and the thickness of its outer covering.
  • Which species the known juvenile belongs to.
  • Whether adults cared for their young.

Often drawn wrong

  • The openings in the frill bone were covered by living tissue, rather than forming see-through holes.
  • A youngster had a shorter, narrower frill than an adult.

Discovery timeline

  1. 1914Named itLambe
  2. 2013How it fedMallon et al.
  3. 2016SkullsCampbell et al.
  4. 2016Growing upCurrie et al.
  5. 2018New findCampbell et al.

Key papers

The research behind what we know of Chasmosaurus

Close relatives

Other members of Ceratopsidae

Sources: Wikidata