Dinosaurs A to Z
Hadrosauridae

Edmontosaurus regalis ed-MON-toh-SOR-us

"Edmonton lizard"

Edmontosaurus silhouette
You 1.8 m (5.9 ft) tall
Edmontosaurus 12 m (39 ft) long
as long as 7 people standing fingertip to fingertip
silhouette · Ivan Iofrida (CC-BY) via PhyloPic
Length
12 m (39 ft) — About 12 m long, ~4 tonnes — one of the largest hadrosaurs.
Period
Late Cretaceous (73–66 Mya)
Place
North America · Alberta, Canada · Montana · Wyoming
Food
Herbivore — Pine needles, conifer twigs, leaves — chewed by a battery of hundreds of teeth.
Clade
Hadrosauridae Dinosauria Ornithischia Cerapoda Ornithopoda Iguanodontia Duck-billed dinosaurs with tooth batteries.

A duck-billed giant that walked alongside Tyrannosaurus right before the dinosaurs vanished.

Edmontosaurus reconstruction by Paleoart by Natee Puttapipat. Published by Stephanie K. Drumheller, Clint A. Boy
Reconstruction · Paleoart by Natee Puttapipat. Published by Stephanie K. Drumheller, Clint A. Boy (CC-BY)

Edmontosaurus was the cow of the Cretaceous — enormously abundant, found from Alaska to Texas in vast herds. It had no crest, a broad duck-bill snout, and the dental battery typical of hadrosaurs: hundreds of teeth fused into a grinding surface. Edmontosaurus lived alongside Tyrannosaurus and made up a major part of its diet.

More about Edmontosaurus

Discovery

Named by Lawrence Lambe · 1917 · the Horseshoe Canyon Formation (formerly the lower Edmonton Formation) along the Red Deer River of southern Alberta, Canada

Lambe coined the genus for two partial skeletons. The type species E. regalis is based on NMC 2288, discovered in 1912 by Levi Sternberg, and the second specimen (paratype NMC 2289) was found in 1916 by George F. Sternberg.

The name means "lizard from Edmonton." It comes from the Edmonton Formation (now the Horseshoe Canyon Formation), which was itself named after Edmonton, the capital city of Alberta.

Lawrence Lambe. The paleontologist who named the type species Edmontosaurus regalis in 1917, initially describing only the skulls before returning in 1920 to describe the skeleton of NMC 2289.

For the curious → Was the huge "Anatotitan" really just a big Edmontosaurus?
Traditionally E. regalis was regarded as the largest species. That changed with the hypothesis that the larger hadrosaurid Anatotitan copei is actually a synonym of E. annectens, put forward by Jack Horner and colleagues in 2004 and supported by studies from Campione and Evans in 2011. Under this view, E. annectens becomes the larger of the two species.
How big did Edmontosaurus actually get?
Size estimates have shifted over time. A 2022 study on the osteohistology and growth of E. annectens suggested earlier estimates may have underestimated or overestimated its size, proposing revised figures for a fully grown adult based on comparisons across specimens from the Ruth Mason Dinosaur Quarry and other sites.

What we know

  • One of the last and most abundant hadrosaurs.
  • Mummified specimens preserve skin impressions — bumpy scales, no feathers.
  • Lived alongside T. rex and Triceratops in the final two million years of the Cretaceous.
  • Found in massive bonebeds with hundreds of individuals — possibly migratory herds.

What we guess

  • Whether large fleshy combs grew from the top of the head in life (one specimen suggests yes).
  • Whether herds migrated seasonally between Alaska and the U.S. interior.
  • How fast it ran — most evidence supports moderate (~25 km/h) escape speed.