Evolution of the Dinosaurs

Dinosaur Ancestors

What are vertebrates?

The first vertebrates, or animals with backbones, evolved during the late Cambrian to early Ordovician periods as jawless freshwater fish that looked much like today’s hagfish and lampreys. By the Devonian period (the “age of fishes”), jawed and armored fishes dominated the oceans. Around 380 million years ago, a line of fish with bony skeletons developed air-breathing lungs and “limbs” strong enough to support them. These were the precursors to the amphibians, creatures that made their first move toward land probably in response to the spread of plants to land around the early Silurian period.


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