New research published today in Science Advances reveals that the largest expansion of coral reefs in the past 100 million years happened about 20 to 10 million years ago, between Australia and Southeast Asia.

This vast reef system likely laid the foundations for the extraordinary diversity of marine life we see today.

Coral reefs are among the most diverse ecosystems on Earth. They support about a quarter of all marine species while covering less than 1% of the oceans. Yet scientists have long grappled with the question of how such immense diversity arose in the first place. Where did it begin, and what made it possible?

Our new study uncovers a turning point deep in Earth’s history – a time when reefs didn’t just grow, but expanded on a scale far beyond anything we see today. This expansion may have created the ecological space needed for modern coral reef life to flourish.

Biodiversity simply refers to the variety of life in a given place. On coral reefs, this diversity is staggering: thousands of species of fish, corals and........

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