These familiar marine arthropods first arose about 545 million years ago in the early Cambrian and thrived throughout the world's oceans until they were wiped out in the Permian extinctions about ...

dramatically. It was the time of the Cambrian Explosion, an eruption of life when Earth’s very first animals began appearing in the fossil record — the ancestors of all major animal groups ...

Lampreys and hagfish are these fishes' living descendants. The archaic sponge reef-dwellers of the Cambrian gave way to ... There is also evidence that the first primitive plants began to appear ...