were among the most successful organisms ever to populate Earth. These familiar marine arthropods first arose about 545 million years ago in the early Cambrian and thrived throughout the world's ...

Since soon after our planet formed, Earth's 4.6 billion-year-long history was dominated by single-celled life. Something ...

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 ...