Earth’s history is filled with incredible milestones, and the emergence of the first animals is one of the most captivating.

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 ...

The first creatures ... all the animals depending on that ice for hunting, resting, reproducing, and other key life activities lose the platform on which their existence depends. At the other end of ...