Iguanodontians

By | September 9, 2016

The iguanodontians were among the most common and widespread dinosaurs of the Late Jurassic and the Cretaceous. They varied from small, nondescript dinosaurs to giants with horselike faces and hugesails on their backs, but all had beaked mouths for eating plants. The iguanodontian group also includes the large duck-billed dinosaur family.

FAMILY FACT FILE

Key features
■ Toothless beaks for clipping plants
■ Hooflike claws
■ Mobile jaws able to chew plant
■ Stiff tails

When
Iguanodontians appeared 156 million years ago, in the Late Jurassic Period. They died out at the end of the Cretaceous Period, 65 million years ago.

Iguanodon (ig-GWAH-no-don)

iguanodon


When: 135–125 million years ago (Early Cretaceous)

Fossil location: Belgium, Germany, France, Spain, England

Habitat: Woodlands

Length: 30 ft (9 m)

Diet: Plants

Discovered in the 1820s, Iguanodon was the second prehistoric animal to be identified as a dinosaur. Its name means “iguana teeth” as its teeth looked like those of an iguana but were 20 times bigger. Iguanodon was as big as an elephant and walked mainly on all fours, feeding on low-growing plants. Its hind legs were larger and more powerful than its front legs, allowing it to stand and perhaps run on two feet.

HANDY

The three middle fingers of Iguanodon’s hands were joined to form a hoof. It could fold its little finger across its palm to grasp objects, and its thumb had a vicious spike, perhaps for self-defense.

Dryosaurus (DRY-oh-SORE-us)

dryosaurus


When: 155–145 million years ago (Late Jurassic)

Fossil location: USA

Habitat: Woodlands

Length: 10 ft (3 m)

Diet: Leaves and shoots

This small and lightly built herbivore had long and powerful legs—a sign that it was a fast runner. It had a stiff tail to help balance its body while running and may have flicked the tail sideways to make sharp turns to dodge obstacles or outwit pursuers.

Camptosaurus (CAMP-toe-SORE-us)

camptosaurus


When: 155–145 million years ago (Late Jurassic)

Fossil location: USA

Habitat: Open woodlands

Length: 16 ft (5 m)

Diet: Low-growing herbs and shrubs

Camptosaurus was one of the most common iguanodontians and looked like a small version of Iguanodon, with a similar long, horselike face tipped by a beak. Its hands, like those of Iguanodon, had hooflike middle fingers and a thumb spike.

Muttaburrasaurus (MOO-tah-BUH-ruh-SORE-us)

muttaburrasaurus


When: 100–98 million years ago (Early Cretaceous)

Fossil location: Australia

Habitat: Woodlands

Length: 23 ft (7 m)

Diet: Plants

The bone forming the top of Muttaburrasaurus’s snout bulged upward, giving this dinosaur an arched nose. It may have used its large nasal chambers to create honking sounds or to warm cold air as it breathed in. The size and shape of its snout differed between individuals and probably varied with sex and age.

Tenontosaurus (ten-NON-toe-SORE-us)

tenontosaurus


When: 115–108 million years ago (Early Cretaceous)

Fossil location: USA

Habitat: Woodlands

Length: 23 ft (7 m)

Diet: Plants

Some dinosaurs are famous for having served as lunch for others. Tenontosaurus was one such unfortunate creature. Remains of this herbivore are often found with teeth of the small but ferocious carnivore Deinonychus, which may have brought down the bigger dinosaur by hunting in packs. Bones of both have also been found together, suggesting that Deinonychus didn’t always survive the battles.

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