The Cambrian Explosion

What happened

In a geologically brief interval beginning about 539 million years ago, animals rapidly diversified into a wide range of body plans. Most of the major animal groups — the phyla we recognise today — first appear in the fossil record during this burst.

Why it matters

The Cambrian explosion established the fundamental architecture of animal life that still dominates the planet, likely triggered by rising oxygen, a warming climate, and new marine habitats.

Sources

• Natural History Museum. The Cambrian Period: How animals exploded onto the scene · Reputable source