Читать книгу The Handy Dinosaur Answer Book - Patricia Barnes-Svarney - Страница 73

As time went on, another phase of dinosaur evolution took place. The animals’ skeletal structure changed, especially the hips, which gave many of the dinosaurs the ability to run on two legs. Euparkeria was a small lizard-like reptile that lived on land and walked on all fours, but it could run on two legs when in a hurry. Further along in time was Ornithosuchus, or “bird crocodile,” which was a two-legged predator. Its front limbs were too small to use for walking on all fours, and its thighs were nearly vertical. From this evidence, it appears that Ornithosuchus walked only on its hind legs.

How were the dinosaurs unique among the reptiles?

Dinosaurs, unlike other reptiles, had their legs tucked in underneath their bodies. This gave them the ability to run and walk very efficiently, eventually leading to some species becoming totally bipedal (two-footed). They also had a keener sense of smell, sight, and hearing, unlike the amphibians and primitive reptiles.