Skeletons made their debut among the first vertebrate ancestors of modern fish, reptiles, birds and mammals.
And specialised survival skills such as swimming or burrowing were developed by the exotic new organisms.
Specimens recovered just 500 miles from the North Pole have shown how a raft of different creatures emerged along with embryonic forms of a modern ecosystem hundreds of millions of years ago during the Cambrian period.
The boom was the result of a critical mix of biological, geological and geochemical processes coming together, setting off a rampant chain reaction dubbed by scientists as the Cambrian Explosion.
The four-year study of Arctic fossils by Oxford and Durham universities says the "cascade of events" commenced 520 million years ago, beginning with a rise in sea levels, that gave a significant boost to the evolutionary machine.
The study has been published in the journal Science.
Edited by Sunita Patel-Carstairs
