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Nature^79

ICHTHYOSAURS

These reptiles spent their lives in the sea,

surfacing to breathe. Ichthyosaurs, which

means fish lizards, gave birth to live young

and fed on fish, squid, and ammonites. The

largest was up to 15 m (49 ft) long.

PTEROSAURS

Pterosaurs belong to the same group

of reptiles as dinosaurs and are closely

related. The largest, Pteranodon, had

a wingspan of up to 9 m (30 ft).

1 ICHTHYOSAURUS

The dolphin-like Ichthyosaurus had a streamlined body, with flippers,

fins, and a long, narrow jaw with spiky teeth. It swam by beating its tail

from side to side, reaching speeds of up to 40 km/h (25 mph).

DINOSAUR STANCE

LIZARD STANCE

WERE PTEROSAURS THE ANCESTORS OF BIRDS?

Birds and pterosaurs evolved separately. Similarities

in skeletons show that birds evolved from saurischian

dinosaurs. But birds and pterosaurs have similar

features, including a streamlined shape, wings, hollow

bones, and a lightweight beak. A furry body suggests

that, like birds, pterosaurs were warm-blooded.

Unrelated living things sometimes develop similar

features to suit similar lifestyles.

WAS OCEAN LIFE VERY DIFFERENT

IN THE AGE OF THE DINOSAURS?

Life beneath the ocean looked much as it does today.

It teemed with animals such as sharks, starfish, corals,

whelks, jellyfish, and lobsters. However, swimming

alongside them were huge and now-extinct marine

reptiles, such as plesiosaurs and ichthyosaurs.

HOW WERE DINOSAURS DIFFERENT

FROM REPTILES TODAY?

Dinosaurs stood upright on straight legs. Their legs

were directly under them, so their bodies were always

raised off the ground. This allowed them to grow

bigger and let them move faster. Reptiles today have

a sprawling stance, with legs held out to the sides.

Their bodies are close to or resting on the ground.

This limits their size and their ability to move.

Large feet with four

claws supported the

dinosaur as it moved

on two legs

Powerful jaws

lined with saw-

edged teeth tore

chunks of flesh

out of prey

Long, heavy tail

helped Giganotosaurus

to balance as it ran

Wings of leathery skin,

reinforced with fine,

tough fibres

Sharp claws

on three fingers

gripped prey while

Giganotosaurus took

deep bites

Tail is stiffened with

rod-like bones

Long fourth finger

forms the edge of the wing

4 DIMORPHODON

This pterosaur grew up

to 1 m (3 ft 3 in) long,

from the tip of its

tooth-lined beak to

the end of its tail.

FIND OUT MORE. Birds 118–119 • Evolution 74–75 • Reptiles 116–117