Kinds of dinosaurs

Duck-billed dinosaurs

A big dinosaur with a beak like a duck's? That's a hadrosaur, a duck-billed dinosaur. They ate plants, lived in herds, and some of them wore a crest on their heads like a hat.

Find out which duck bill is which, and why one of them had a thousand teeth.

An old painting of two duck-billed dinosaurs by a lake, one sitting up on its back legs and one drinking
Duck-billed dinosaurs as Charles R. Knight painted them in 1897. Today scientists think they spent most of their time on all fours.

The short answer

  • Duck-billed dinosaurs are called hadrosaurs. Edmontosaurus, Maiasaura and Corythosaurus are three of them.
  • The “duck bill” is a wide, flat beak with no teeth at the front. Behind it sat hundreds of grinding teeth.
  • Some had a crest on the head: a helmet, a hatchet or a long hollow tube.

Spot the difference

Which duck bill is which?

Duck bills all had the same kind of body. To tell them apart, look at the top of the head. (The pictures aren't to scale.)

  • Edmontosaurus, an outline

    Edmontosaurus

    Say it: ed-MON-toe-sore-us · “Edmonton lizard”

    Look for: No fancy crest. A long head with a wide, flat beak.

    The longest one on this page, about 13 meters (43 feet). It lived at the same time as T. rex.

  • Maiasaura, an outline

    Maiasaura

    Say it: my-ah-SORE-ah · “good mother lizard”

    Look for: A plain duck bill, about 9 meters (30 feet) long.

    Famous for its nests, found at a place in Montana called Egg Mountain.

  • Corythosaurus, an outline

    Corythosaurus

    Say it: koh-rith-OH-sore-us · “Corinthian helmet lizard”

    Look for: A tall, narrow crest shaped like a helmet.

    About 10 meters (33 feet) long.

  • Lambeosaurus, an outline

    Lambeosaurus

    Say it: lam-BEE-oh-SORE-us · “Lambe's lizard”

    Look for: A crest shaped like a hatchet.

    The crest was hollow, with air passages from its nose running through it.

  • Parasaurolophus, an outline

    Parasaurolophus

    Say it: pa-ra-saw-ROL-off-us

    Look for: A long, hollow tube sweeping back from its head.

    Scientists have worked out the sound it could make by blowing air through that tube: a deep, low bellow.

  • Hadrosaurus, an outline

    Hadrosaurus

    Say it: HAD-row-SORE-us · “big lizard”

    Look for: The one that gave the whole family its name.

    It was dug up in New Jersey in 1858. Ten years later it became the first dinosaur skeleton ever put on show.

The name

Why are they called duck-billed dinosaurs?

Because of the snout. It was wide and flat, like a duck's bill, with no teeth at the front. But that's where the duck ends. Hadrosaurs didn't paddle about on ponds. They were big land animals that ate tough plants.

Two legs or four?

Both. They probably spent most of their lives walking on all fours, but they could rise up on their back legs.

Safety in numbers

Duck bills lived in herds, young and old together. Fossil footprints of big ones and little ones have been found in the same place.

An older cousin with spiky thumbs

Before the duck bills came Iguanodon. It had a big spike on each thumb. The first scientists to rebuild it put the spike on its nose, like a rhino's horn!

Behind the beak

The dinosaur with a thousand teeth

A duck bill had no teeth at the front of its mouth, but look further back. Edmontosaurus had 1,000 grinding teeth, packed together in rows. It only used a few at a time. The rest waited underneath, ready to move up when a tooth wore out.

And they did wear out. Chewing pine needles, twigs and seeds all day is hard work. By the end of the dinosaurs' time, a duck bill could wear through a tooth in as little as 50 days.

Compare that with one of the long necks, which didn't chew at all:

Even though Brachiosaurus had only 50 teeth or less, it could eat 100 to 400 kilograms (220 to 881 pounds) of plants every day!
Katia, in Dinosaurs Are Back

What was for dinner?

Pine needles, twigs and seeds have been found in the stomachs of Edmontosaurus.

Who hunted them?

T. rex tooth marks have been found on Edmontosaurus bones. The other duck bills lived a little earlier, and had earlier cousins of T. rex to worry about.

T. rex facts, and T. rex in 3D

A T. rex's lunch, in fossil poo

A fossil poo from a T. rex, found in Canada, was full of bone from a young duck bill.

How scientists know who ate what

Skin and all

A dinosaur mummy

Most fossils are only bones. But two Edmontosaurus fossils found in Wyoming are so well kept that people call them mummies. You can see the pattern of the scales on the skin, the hard beak, and even the pads on the hands.

Another one, nicknamed Dakota, was found by a high school student in North Dakota in 1999.

An old black and white photograph of a fossil duck-billed dinosaur lying on its back, with its skin still stretched over the ribs
One of the Edmontosaurus mummies, at the American Museum of Natural History in New York. Photographed in 1912.

The good mother lizard

Maiasaura means “good mother lizard”. At Egg Mountain in Montana, scientists found its nests, its eggs and its young at different ages, all in one place.

Dinosaur eggs and nests

The first dinosaur on show

Hadrosaurus was dug up in Haddonfield, New Jersey, in 1858. In 1868 its skeleton was put on a stand in a museum in Philadelphia: the first dinosaur ever mounted and shown to the public.

Helmets, hatchets and tubes

What were the crests for?

Nobody knows for sure. The crests were hollow, with long air passages from the nose running through them. Experts think a crest may have helped a dinosaur to spot others of its own kind, to make loud sounds, or to keep cool or warm.

Other dinosaurs had crests too. Dilophosaurus, a meat-eater, had two.

Questions kids ask

Quick answers

What is a duck-billed dinosaur called?
A hadrosaur. Edmontosaurus, Maiasaura, Corythosaurus and Lambeosaurus were all hadrosaurs. The group is named after Hadrosaurus, the first one ever named.
Why are they called duck-billed dinosaurs?
Because of their wide, flat snouts, which look like a duck's bill. But they weren't much like ducks: they were big plant-eaters that lived on land.
How many teeth did a duck-billed dinosaur have?
Hundreds. Edmontosaurus had 1,000 grinding teeth! It only used a few at a time. The rest waited underneath, ready to take over when a tooth wore out.
What did duck-billed dinosaurs eat?
Tough plants. Pine needles, twigs and seeds have been found in the stomachs of Edmontosaurus.
Did duck-billed dinosaurs walk on two legs or four?
Both. They probably spent most of their time on all fours, but they could rise up on their back legs.
Which duck-billed dinosaurs had a crest?
Corythosaurus had a crest like a helmet, Lambeosaurus one like a hatchet, and Parasaurolophus a long hollow tube. Edmontosaurus had no fancy crest at all.
What is a dinosaur mummy?
A fossil that still shows the animal's skin. Two Edmontosaurus mummies found in Wyoming show the pattern of the scales, the beak and even the pads of the hands.
Did T. rex eat duck-billed dinosaurs?
Yes. T. rex tooth marks have been found on Edmontosaurus bones.

Keep sorting

More kinds of dinosaurs

Got a big question instead? The biggest, the fastest, the fliers and the long necks. Or meet ten dinosaurs, one page each, with a fun fact and a riddle.

Cover of Dinosaurs Are Back, an interactive 3D dinosaur book in augmented reality

Our own bookA picture book · ages 6 to 10

Dinosaurs Are Back

T. rex hunted duck bills. In this story it hunts Spike, a young Triceratops, for hours, and then it offers to help him. Ten dinosaurs step off the page with a phone or tablet.

Buy on Amazon · $14.99Look inside

Where these facts come from

Katia's facts are from the fact page near the end of Dinosaurs Are Back. Everything else was checked on these pages on October 1, 2026.

Picture credits