Kritosaurus
KRIT-oh-SORE-us
"separated lizard"
- Lived
- 84 to 66 million years ago, Late Cretaceous
- Diet
- Herbivore
- Length
- about 8 m (26 ft)
- Group
- Ornithopods, Hadrosauridae
- Found in
- United States
- Named by
- Brown 1910
Size comparison
To scale
Scale in metersOutline: typical ornithopod shape
Where its fossils were found
The evidence
Today
75 million years ago
Habitat
It lived on river plains in the southwestern United States. The Kirtland Formation also preserves Parasaurolophus and Daspletosaurus.
Field notes
About Kritosaurus
What it was like
Kritosaurus was a duck-billed plant eater about 8 meters (26 feet) long. It had a broad beak and rows of grinding teeth. The first skull was broken at the snout, and early drawings restored it with a flat face; later finds suggest it had a raised, arched nose, like a hooked nose.
Its world
It lived in the Late Cretaceous in what is now the southwestern United States, with finds from New Mexico and Texas. Its bones come from the Kirtland Formation and others nearby, where it shared the land with the crested Parasaurolophus and the tyrannosaur Daspletosaurus.
How it was found
Brown named Kritosaurus in 1910. Because the first skull was so incomplete, scientists have long argued over which later fossils belong to it, and some once placed Gryposaurus in the same genus.
Field gallery
More views of Kritosaurus
Scenes reconstructed from the available fossil evidence.
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 Kritosaurus.
The evidence
The science behind Kritosaurus
Which parts of the picture come from its own bones, and which come from its relatives.
From its own fossils
- The original skull preserves much of the back of the head and jaws, including rows of closely packed teeth.
- The shapes of the upper jaw, cheekbone and bones around the eye help distinguish Kritosaurus from other duck-billed dinosaurs.
- Paired projections at the back of the nasal bones rested over the skull roof.
Borrowed from relatives
- Edmontosaurus helps restore the missing broad muzzle and much of the body.
- The supporting hand pads and broad rear toes follow better-preserved duck-billed dinosaurs such as Edmontosaurus.
Still unknown
- The exact outline and height of its nasal ornament.
- Which of the many fossils once assigned to Kritosaurus truly belong to it.
- Its skin color and any soft decorations on its head.
Often drawn wrong
- Early flat-faced restorations filled in the broken snout of the first skull.
- The large nose arch of Gryposaurus should not be copied as the exact crest of Kritosaurus.
Discovery timeline
- 1910Named itBrown
- 2013Full descriptionPrieto-Márquez
- 2024SkullLongrich et al.
Key papers
The research behind what we know of Kritosaurus
Named it
Named Kritosaurus from an incomplete duck-billed dinosaur skull with a broken snout.
The Cretaceous Ojo Alamo beds of New Mexico with description of the new dinosaur genus <i>Kritosaurus</i>. Bulletin of the American Museum of Natural History 28: 267-274
No link available
Full description
Restudied the skeleton and identified jaw, cheek and skull-roof features that distinguish Kritosaurus from other duck-billed dinosaurs.
Skeletal morphology ofKritosaurus navajovius(Dinosauria: Hadrosauridae) from the Late Cretaceous of the North American south-west, with an evaluation of the phylogenetic systematics and biogeography of Kritosaurini. Journal of Systematic Palaeontology 12: 133-175
Read the paper : Skeletal morphology ofKritosaurus navajovius(Dinosauria: Hadrosauridae) from the Late Cretaceous of the North American south-west, with an evaluation of the phylogenetic systematics and biogeography of Kritosaurini (opens in a new tab)Skull
Identified a skull once assigned to Kritosaurus as a different genus, Coahuilasaurus, based on its distinctive snout and jaws.
Coahuilasaurus lipani, a New Kritosaurin Hadrosaurid from the Upper Campanian Cerro Del Pueblo Formation, Northern Mexico. Diversity 16: 531
Read the paper : Coahuilasaurus lipani, a New Kritosaurin Hadrosaurid from the Upper Campanian Cerro Del Pueblo Formation, Northern Mexico (opens in a new tab)
Close relatives
Other members of Hadrosauridae
Sources: Wikidata