The Ocean Through Time

Life began in the ocean around 3.5 billion years ago and as evolution progressed, many species went extinct -- and some left behind fossils -- as others appeared. And even now, the ocean hasn't stopped changing as evolution continues and humans leave their mark.

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Did Whale Evolution Go Backwards?

Whales swim, but their ancestors walked. Whales are mammals (like us) whose ancestors lived on land. Life probably began in...