Animal Origins Revealed by Rethinking Fossil Record

Animal origins have puzzled biologists ever since Darwin documented the process of natural selection. Find out how a new study of how fossils form helps scientists establish when animal life first arose on Earth.

As Canada Day approaches, I’m planning my usual trip to the family cottage. One of the activities I’ve enjoyed there since childhood has been fossil hunting on the Bruce Peninsula’s limestone beaches.

The rocks there are teeming with fossils, marine animals beautifully preserved in their sedimentary layers. Most of the fossils record the shapes of invertebrates with bivalve shells called brachiopods.

We keep some of the best samples we’ve collected on a shelf in the den as reminders of our summer home. Glancing at them now reminds me of something that’s always puzzled me about the fossil record.

Cambrian Explosion — Remarkable Burst of Biodiversity

Based on the animal remains preserved in Canada and around the globe, there was a remarkable burst of biodiversity around 539 million years ago. Scientists call it the Cambrian explosion, because a wide range of complex animal…