Edmontosaurus
Meet the big duck-billed dinosaur that lived with T. rex! Discover how big it was, why it had hundreds of teeth, and what amazing dinosaur mummies have taught us.
What was Edmontosaurus?
Edmontosaurus was a giant duck-billed dinosaur that ate plants. It lived in North America about 73 to 66 million years ago, grew up to 39 feet (12 m) long, and shared its world with T. rex and Triceratops.
Meet Edmontosaurus
Edmontosaurus (say ed-MON-toe-SORE-us) was one of the biggest duck-billed dinosaurs, also called hadrosaurs. Its name means "Edmonton lizard" because the first skeletons were found in rocks near Edmonton, in Alberta, Canada. Scientist Lawrence Lambe gave it its name in 1917.
It had a long, flat head with a wide beak shaped like a duck's bill, strong back legs, shorter front legs, and a long, stiff tail. Most of the time it walked slowly on all four legs while it munched on plants. When it needed to hurry, it could stand up and run on its two back legs.
Edmontosaurus was a gentle herbivore. It had no horns, spikes or sharp claws. Its best ways to stay safe were its huge size, its speed, and living in big groups called herds.
Edmontosaurus Quick Facts
| Pronounced | ed-MON-toe-SORE-us |
|---|---|
| Name means | Edmonton lizard |
| Type | Hadrosaur (duck-billed dinosaur) |
| Diet | Herbivore (plants) |
| Length | Up to about 39 ft (12 m) |
| Weight | About 6 tons (5.6 tonnes) |
| When | 73–66 million years ago, Late Cretaceous |
| Where | Western North America, Colorado to Alaska |
| Named by | Lawrence Lambe, 1917 |
Fun Facts About Edmontosaurus
How Big Was Edmontosaurus?
A grown-up Edmontosaurus was usually about 36 to 39 feet (11 to 12 metres) long. That is about as long as a school bus! It weighed around 6 tons, about the same as an African elephant. A few giant ones may have been even bigger.
Baby Edmontosaurus hatched from eggs and grew very fast. Scientists think they reached adult size in only about 9 to 10 years. Growing big quickly helped them stay safe from hungry predators.
📏 Try this: Take 39 big steps across a park or playground. That is roughly how long an Edmontosaurus was from beak to tail!
What Did Edmontosaurus Eat? (Hundreds of Teeth!)
Edmontosaurus was a plant eater. Fossils found inside the belly area of one skeleton included conifer needles, twigs and seeds, so it probably ate tough plants like pine and other trees, plus bushes and low plants. It could reach food from the ground up to about 13 feet (4 m) high.
The front of its mouth was a toothless beak, great for snipping off leaves. But at the back of its jaws were hundreds of teeth stacked tightly together in rows called dental batteries. They worked like a rough grater that ground plants into mush. When a tooth wore down, a new one was already growing underneath to replace it.
🦷 Love toothy dinosaurs? Meet Nigersaurus, a long-necked dinosaur with about 500 teeth, on our What Dinosaur Has 500 Teeth? page.
Edmontosaurus Mummies: Skin, Crests and Hooves
Most dinosaurs are known only from bones. Edmontosaurus is special because scientists have found several dinosaur "mummies". These are fossils where the shape of the skin was saved in the rock too, so we know much more about what Edmontosaurus really looked like.
- 1908: fossil hunters in Wyoming found the first Edmontosaurus mummy. It is still on show at the American Museum of Natural History in New York.
- 1999: a teenager found a mummy nicknamed "Dakota" in North Dakota. Its skin was covered in small, bumpy scales.
- Canada: one mummy had a soft, fleshy crest on top of its head, a little like a rooster's comb!
- 2025: scientists led by Paul Sereno studied two mummies from Wyoming. They showed a fleshy crest running down the neck and back, a row of spikes along the tail, tiny pebbly scales, and hooves on its feet. They are the first hooves ever found on a dinosaur!
🐴 Fun fact: Edmontosaurus had hooves a bit like a horse! They helped it walk on soft, muddy ground.
Did Edmontosaurus Live With T. rex?
Yes! Edmontosaurus lived in the same places and at the same time as Tyrannosaurus rex. It was one of the most common plant eaters around, so it was probably one of T. rex's favourite meals.
But Edmontosaurus did not always get caught. Scientists found an Edmontosaurus skeleton with a T. rex bite on the top of its tail. The broken bone had healed, which means the Edmontosaurus got away and lived for a long time after the attack!
Edmontosaurus also lived beside Triceratops, Ankylosaurus and Pachycephalosaurus. See more of its neighbours on our Names of Dinosaurs and Types of Dinosaurs pages.
Where Did Edmontosaurus Live?
Edmontosaurus lived in western North America. Its fossils have been found in Alberta and Saskatchewan in Canada, and in Montana, Wyoming, North Dakota, South Dakota and Colorado in the United States.
Back then, much of this land was warm and wet, with rivers, swamps and forests near the coast of a big inland sea. Edmontosaurus liked these coastal plains.
Some Edmontosaurus lived as far north as Alaska, inside the Arctic! There, winters were cold and dark for months. Scientists have found many bones in one place, called bonebeds, which show that Edmontosaurus lived in herds and may have travelled together.
Western North America
From Colorado all the way up to the north slope of Alaska
What Happened to Edmontosaurus?
Edmontosaurus was one of the very last dinosaurs. It was still alive about 66 million years ago when a giant asteroid crashed into Earth. The disaster changed the weather all over the world, and Edmontosaurus, T. rex and all the other big dinosaurs died out.
Learn the whole story on our When Did Dinosaurs Go Extinct? page, and find out which dinosaurs are still around today on Are Birds Dinosaurs?
Edmontosaurus Activities for Kids
- Duck bill game:make a "duck bill" with two hands and pretend to snip leaves like Edmontosaurus.
- Two legs or four?Walk slowly on hands and feet like a grazing Edmontosaurus, then stand up and run on two legs when the "T. rex" is coming!
- Count the teeth: ask your child to count their own teeth (kids have about 20) and compare them with the hundreds in an Edmontosaurus jaw.
- Color a dinosaur: print a free page from our Dinosaur Coloring Pages and give it a duck bill and a crest down its back.
Frequently Asked Questions
What kind of dinosaur is Edmontosaurus?
Edmontosaurus was a hadrosaur, which is a duck-billed dinosaur. It was a big plant eater with a wide, flat beak and hundreds of grinding teeth in the back of its mouth.
How do you say Edmontosaurus?
Say it ed-MON-toe-SORE-us. The name means "Edmonton lizard" because its first fossils were found near Edmonton in Alberta, Canada.
How big was Edmontosaurus?
The biggest Edmontosaurus grew up to about 39 feet (12 metres) long, about as long as a school bus, and weighed around 6 tons, about as much as an African elephant.
When did Edmontosaurus live?
Edmontosaurus lived about 73 to 66 million years ago, at the very end of the Cretaceous period. It was one of the last dinosaurs alive before the asteroid hit.
Did Edmontosaurus live with T. rex?
Yes! Edmontosaurus lived at the same time and in the same places as Tyrannosaurus rex and Triceratops. Scientists have even found an Edmontosaurus tail bone with a healed T. rex bite, which means that Edmontosaurus escaped.
How many teeth did Edmontosaurus have?
Edmontosaurus had hundreds of teeth packed into tight stacks called dental batteries. Only a few were used at a time, and new teeth kept growing in to replace worn ones.
Did Edmontosaurus have a crest?
It had no bony crest on its skull like Parasaurolophus. But fossil mummies show it had a fleshy crest running along its neck and back, and one mummy from Canada had a soft, fleshy crest on its head, a bit like a rooster's comb.
Where have Edmontosaurus fossils been found?
Edmontosaurus fossils come from western North America: Alberta and Saskatchewan in Canada, and Montana, Wyoming, North Dakota, South Dakota and Colorado in the United States. Some even lived as far north as Alaska.
Sources: Wikipedia's Edmontosaurus article and the studies it cites; Sereno et al., Science (October 2025); Carpenter (1998) on the healed T. rex bite.
Image credits, via Wikimedia Commons: top image, Edmontosaurus reconstruction by Die Infografen (CC BY-SA 4.0); Edmontosaurus annectens life restoration by Connor Ashbridge (CC BY 4.0); adult and young skeletons by MCDinosaurhunter (CC BY-SA 3.0); healed T. rex bite by Kenneth Carpenter (CC BY-SA 4.0).
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