SYDNEY, May 4 (Xinhua) -- The waters between Australia and Southeast Asia were once a hotspot for new and mammoth coral reefs, laying the foundations for today's marine biodiversity, new research has revealed.

The study, led by Australia's Edith Cowan University (ECU), shows the largest expansion of coral reefs in the past 100 million years happened 20 to 10 million years ago in this region, now the world's most biologically-rich marine area, said an ECU statement released Monday.

"Coral reefs are among the most biodiverse ecosystems on Earth, supporting around a quarter of all marine species while covering less than one percent of the oceans," said Alexandre Siqueira with ECU's Center for Marine Ecosystems Research, the study's lead author.

The research, combining geological records, fossil and genetic data, showed changes in environmental, biological and tectonic conditions about 20 million years ago promoted the dramatic expansion of coral reefs across the region, now known as the Indo-Australian Archipelago.

"These independent lines of evidence allowed us to pinpoint when and where modern reef biodiversity began to take shape," Siqueira said, adding that coral reefs expanded dramatically at a key point in time, coinciding with the emergence of many modern coral and iconic fish lineages, including parrotfishes.

"As reefs grew larger, they likely created new habitats and ecological opportunities, allowing species to evolve and diversify," he said.

The findings, published in Science Advances, suggest that reefs off northwestern Australia may be remnants of what was once one of the largest reef systems to have ever existed. ■