Edmontosaurus
A large duck-billed dinosaur from the end of the Cretaceous.
Edmontosaurus (ed-MON-tə-SOR-əs) is a genus of hadrosaurid (duck-billed) dinosaur whose fossils have been found in western North America. It lived during the late Campanian and Maastrichtian ages of the Cretaceous period, approximately 73 to 66 million years ago, and was one of the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event. The genus includes two known species: *Edmontosaurus regalis* and *Edmontosaurus annectens*. Often historically referred to as *Anatosaurus* or *Anatotitan*, these animals were among the largest hadrosaurids. *E. annectens* could reach substantial lengths and weights, with exceptionally large specimens measuring even more. Numerous well-preserved skeletons have been recovered, many retaining extensive skin impressions and possible gut contents. Unlike crested hadrosaurids, *Edmontosaurus* belonged to the saurolophine group, possessing only small, solid crests or fleshy combs. The first fossils named *Edmontosaurus* were found in southern Alberta’s Horseshoe Canyon Formation, and the type species *E. regalis* was named by Lawrence Lambe in 1917. However, the older species *E. annectens* was originally named *Claosaurus annectens* by Othniel Charles Marsh in 1892, based on partial skeletons from Wyoming. This species later spent years classified under *Trachodon* and *Anatosaurus* before being reassigned. *Edmontosaurus* ranged widely from Colorado to Alaska, favoring coastal plains. It was a herbivore capable of moving on two or four legs, and bone beds suggest it lived in groups and may have migrated. The wealth of fossils has allowed detailed study of its brain, feeding habits, and injuries, including evidence of tyrannosaur attacks. In 2025, researchers detected ancient hydroxyproline—a collagen building block—in an *Edmontosaurus* fossil, providing the first clear detection of original dinosaur organic material and refuting claims that such matter must be contamination.
- scientific_name
- Edmontosaurus
- meaning
- lizard from Edmonton
- time_period
- Late Cretaceous (Campanian to Maastrichtian)
- length
- up to 15 meters (49 ft) in exceptionally large specimens
- mass
- up to 15.9 metric tons (17.5 short tons) in exceptionally large specimens
- diet
- herbivore
- locomotion
- bipedal and quadrupedal
Lore & Background
Edmontosaurus, meaning "lizard from Edmonton," is a genus of hadrosaurid, or duck-billed, dinosaur that includes two known species: *Edmontosaurus regalis* and *Edmontosaurus annectens*. It ranks among the largest hadrosaurids, with *E. annectens* reaching substantial lengths and weights, and exceptionally large specimens being even more massive. The animal is classified as a saurolophine hadrosaurid, meaning it lacked large, hollow crests, instead possessing smaller, solid crests or fleshy combs. Its fossils have been found across western North America, from Colorado to the northern slopes of Alaska, indicating a wide distribution that likely favored coastal plains and coastlines. *Edmontosaurus* was a herbivore capable of moving on both two legs and four. Evidence from multiple bone beds suggests it lived in groups and may have been migratory. Numerous well-preserved specimens have been recovered, including extensive skin impressions, possible gut contents, and bones that have allowed detailed study of its brain, feeding mechanics, and injuries, including evidence of tyrannosaur attacks. In 2025, a fossil of this dinosaur yielded the first clear detection of original dinosaur organic material, specifically ancient hydroxyproline, a building block of collagen, challenging the idea that such organic matter must be contamination. The first fossils named *Edmontosaurus* were discovered in southern Alberta, Canada, in the Horseshoe Canyon Formation.
Reader's Guide
Edmontosaurus is significant for its abundance and preservation quality, including extensive skin impressions and possible gut contents. It is one of the best-studied hadrosaurids, with fossils found from Colorado to Alaska, suggesting a wide distribution and preference for coastal plains. Bone beds indicate it lived in groups and may have been migratory. reported the first clear detection of original dinosaur organic material—hydroxyproline, a collagen building block—in an Edmontosaurus fossil, refuting the idea that such organic matter must be contamination. This discovery has major implications for the study of dinosaur biochemistry and preservation.
Did You Know?
- Edmontosaurus was one of the last non-avian dinosaurs, living alongside Triceratops, Tyrannosaurus, Ankylosaurus, and Pachycephalosaurus.
- Edmontosaurus fossils have been found from Colorado to the northern slopes of Alaska.
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