A massive coral reef network that existed millions of years ago may hold the key to understanding how modern marine biodiversity evolved, according to new research published in Science Advances. Scientists say this ancient system, formed between 20 and 10 million years ago, laid the foundation for the rich ocean life seen today.
The study identifies a vast reef expansion between Australia and Southeast Asia, a region now known for its exceptional marine biodiversity. Researchers believe this large-scale growth of reefs created the ecological conditions necessary for thousands of marine species to emerge and thrive.
Coral reefs today cover less than one per cent of the ocean floor but support nearly a quarter of all marine species. Despite their importance, scientists have long struggled to explain how such extraordinary biodiversity originated. The new findings point to a critical turning point in Earth’s history when reefs expanded at an unprecedented scale.
Massive Reef Expansion Created Space For Marine Evolution
The research highlights how environmental, biological and tectonic changes during the Miocene period triggered the rapid spread of coral reefs across what is now called the Indo-Australian Archipelago. This region includes the Coral Triangle, widely recognised as the global centre of marine life diversity.
Scientists combined geological records, fossil evidence and genetic data to trace the origins of reef biodiversity. Their findings suggest that as reefs expanded, they created new habitats and ecological niches, allowing species to evolve and diversify rapidly.
During this period, many modern marine organisms began to appear, including plating corals and well-known fish groups such as parrotfishes. The researchers have named this ancient network the Great Indo-Australian Miocene Reef System, which they believe played a crucial role in shaping today’s ocean ecosystems.
Remnants Of Giant Reef System Still Exist Today
Although the ancient reef system was once enormous, its remnants are now scattered. Areas off northwestern Australia, including reefs such as Ashmore Reef, Scott Reef and Rowley Shoals, are believed to be surviving fragments of this prehistoric structure.
Previous studies have suggested that this ancient reef rivalled the size of the modern Great Barrier Reef. The new research goes further, indicating that some individual reefs within the system may have been even larger than any reefs that exist today.
Over millions of years, marine biodiversity gradually spread across the Indo-Pacific, building on the foundation created by this early reef expansion. However, scientists note that reconstructing such ancient ecosystems remains challenging due to incomplete geological records.
Despite these uncertainties, the study presents strong evidence that the explosion of coral reef growth millions of years ago played a defining role in shaping life in today’s oceans. Researchers emphasise that understanding Earth’s past is essential to explaining present-day biodiversity and protecting fragile marine ecosystems for the future.