The first dinosaurs

Several groups of reptiles existed before the dinosaurs appeared. One group was the thecodonts. These were the ancestors of the dinosaurs, and they probably also gave rise to the pterosaurs and the crocodiles. Thecodonts were large carnivores that had straighter legs than other reptiles. The first dinosaurs were also carnivores, and the earliest known dinosaur, Eoraptor, first appeared 228 million years ago. tiH*r*r* 1 r:

Long, stiff a very early dinosaur Eoraptor may have been the first dinosaur. It was discovered in 1992 in Argentina. Eoraptor had a crocodile-like skull with sharp, curved teeth.

Jaws were lined with sharp teeth

Long tail acted as a counterbalance to the front of the body

Long, stiff

New Dinosaur Largest

Long tail acted as a counterbalance to the front of the body

Staurikosaurus Speedy Staurikosaurus was one of the first carnivorous dinosaurs. It had long, tooth-lined jaws for catching its prey, which it chased on its long and slender back legs.

First dinosaurs facts

• The earliest -J dinosaurs have come from Triassic period rocks.

• Mammals were around at the same time as the dinosaurs.

• The earliest dinosaurs

Scaly skin typical of reptiles.

: all carnivores.

• The first herbivores appeared in the late Triassic period.

Scaly skin typical of reptiles.

Herrerasaurus A light and slender skeleton made Herrerasaurus an agile hunter. It was about 10 ft (3 m) long and ate other small reptiles.

, Long and narrow head

: all carnivores.

• The first herbivores appeared in the late Triassic period.

, Long and narrow head

Early carnivore Herrerasaurus lived about 230 million years ago. it had many features in common with later carnivorous dinosaurs, such as sharp teeth and claws, and strong back legs.

Two-legged runner Ornithosuchus is the ancestor of the large carnivorous dinosaurs of the Jurassic and Cretaceous periods. It was about 13 ft (4 m) long and walked on all fours, although it ran on its two back legs.

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