Darwin's Headache: Evolution's Clock Might Tick at Different Speeds

Darwin's Headache: Evolution's Clock Might Tick at Different Speeds

The oldest fossilised remains of complex animals appear suddenly in the fossil record, and as if from nowhere, in rocks that are 538 million years old.

A speeding clock could solve Darwin’s mystery of gaps in animal fossil records

Trilobites were among the first complex animals. Couperfield/ShutterstockThe oldest fossilised remains of complex animals appear suddenly in the fossil record, and as if from nowhere, in rocks that are 538 million years old. The very oldest of these are simple fossilised marks (called Treptichnus) made by something worm-like with a head and a tail. A host of other animals appear rapidly, ancestors of the diverse animal groups we know today: anci…