Evolution of the Dinosaurs

Dinosaurs First Appear

What was the next stage in the evolution towards true dinosaurs?

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.


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