The cradle of Earth’s rich ocean life was a massive coral reef system 20 million years ago

Oleksandr Sushko/Unsplash Alexandre Siqueira, Edith Cowan University

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.

Coral reefs are major biodiversity hotspots. Ahmer Kalam/Unsplash

An enduring mystery

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 other organisms coexist in tightly packed ecosystems.

However, despite decades of research, the origins of this richness have remained an enduring mystery.

Our new study reveals that changes in environmental, biological and tectonic conditions about 20 million years ago promoted the dramatic expansion of coral reefs across a region stretching between Australia and Southeast Asia.

Today, this area is known as the Indo-Australian Archipelago. It’s recognised as a global hotspot of marine biodiversity, especially in an area called the Coral Triangle.

The expansion of reefs in this area coincided with the emergence of many familiar reef organisms, including plating corals and iconic fish groups like parrotfishes.

To uncover this, we combined evidence from geological records, fossils and genetic data. Together, these independent lines of evidence allowed us to pinpoint when and where modern reef biodiversity began to take shape, without relying on any single source alone.

Results suggest reef expansion itself played a crucial role in generating biodiversity. As reefs grew larger, they likely created new habitats and ecological opportunities, allowing species to evolve and diversify.

We have now named this ancient network of reefs the Great Indo-Australian Miocene Reef System. The large reefs in this system were mostly built by corals and crustose coralline algae, an essential group of algae for holding together reef structures. These reefs also provided very important habitat for fish groups that we see on coral reefs today, such as surgeonfishes and butterflyfishes.

Remnants of an epic reef

Surprisingly, the region where this expansion occurred is not where the largest reefs are found today. Instead, reefs off northwestern Australia – including Ashmore Reef, Scott Reef, and the Rowley Shoals – may be remnants of what was once one of the largest reef systems to have ever existed.

Previous geological work has shown this ancient west Australian barrier reef rivalled the extent of the present-day Great Barrier Reef. The new findings go further, suggesting individual reefs within this system may have been far larger than any modern reef.

In fact, the roots of modern marine fish and coral biodiversity may lie in this unexpected place off Australia’s west coast. Over millions of years, biodiversity spread and accumulated elsewhere, particularly across the Indo-Pacific Ocean.

However, there are still uncertainties. Reconstructing ecosystems from millions of years ago requires combining incomplete records. Some aspects of reef size and how these ecosystems connected remain difficult to resolve, as the geological record only contains the remnants of entire reef systems.

But the overall pattern is clear. A massive expansion of reefs about 20 million years ago coincided with the rise of modern marine diversity.

The message is also simple. To understand where biodiversity is today, we need to look deep into the past. The richest ecosystems on Earth may owe their origins to places that no longer appear exceptional – hidden chapters of Earth’s history that continue to shape life in our oceans.

Coral reefs support thousands of species in a small area. Francesco Ungaro/Unsplash

Alexandre Siqueira, ARC DECRA and Vice-Chancellor's Research Fellow, School of Science, Edith Cowan University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Read More........→May 05, 2026

Application lodged to build microreactor at US university

A rendering of the KRONOS plant at the University of Illinois Urbana-Champaign (Image: NANO Nuclear)

The US Nuclear Regulatory Commission announced it has received an application from the University of Illinois to construct the first research KRONOS micro modular reactor on the university's campus.

The Construction Permit Application (CPA) was submitted on 31 March by The Grainger College of Engineering at the University of Illinois Urbana-Champaign, NANO Nuclear Energy Inc's partner for the KRONOS MMR deployment at the University of Illinois (U of I).

"With this submission, NANO Nuclear becomes the first commercially-ready microreactor developer and the third commercially-ready Generation IV advanced reactor developer to submit a CPA, placing NANO Nuclear among a small group of advanced nuclear companies progressing toward commercial deployment," the company said.

It added: "The preparation of a CPA represents the culmination of years of engineering development, thousands of pages of technical documentation, coordinated input across reactor design, safety analysis, environmental review, and regulatory compliance disciplines, and establishment of a viable supply chain. In NANO Nuclear's partnership with the U of I, the CPA submission builds on an extensive body of work developed through continuous engagement with the NRC, including completion of the readiness assessment, a voluntary but highly rigorous process aimed at ensuring a complete and high-quality application. Importantly, this iterative process reflects a high level of alignment with regulatory expectations and provides strong confidence in the application's readiness for acceptance for docketing and formal NRC review."

"The NRC is reviewing the application to determine whether it is complete," the regulator said. "If accepted, the agency will begin a detailed technical evaluation of the reactor's safety and security and publish a notice of opportunity to request an adjudicatory hearing on the application before the NRC's Atomic Safety and Licensing Board."

It noted that if the construction permit is granted, the university would need to submit a separate operating licence application and receive NRC approval before the reactor could begin operation.

NANO Nuclear acquired the Micro Modular Reactor Energy System technology through its USD85 million acquisition of Ultra Safe Nuclear Corporation's nuclear technology, which was completed in January last year. At that time, NANO Nuclear renamed the technology as the KRONOS MMR. The MMR is a 45 MW thermal, 15 MW electrical high-temperature gas-cooled reactor, using TRISO fuel in prismatic graphite blocks and has a sealed transportable core.

NANO Nuclear signed a strategic collaboration agreement with the University of Illinois Urbana-Champaign in April 2025 to construct the first research KRONOS micro modular reactor on the university's campus. The agreement formally established the University of Illinois Urbana-Champaign as a partner in the licensing, siting, public engagement, and research operation of the KRONOS MMR, while also identifying the university campus as the permanent site for the reactor as a research and demonstration installation.

The university plans to re-power partially its coal-fired Abbott power station with the KRONOS MMR, providing a zero-carbon demonstration of district heat and power to campus buildings as part of its green campus initiative. The project team aims to demonstrate how microreactor systems integrate with existing fossil fuel infrastructure to accelerate the decarbonisation of existing power-generation facilities."Through every step of the process thus far, we at The Grainger College of Engineering have worked diligently alongside our partners at NANO Nuclear Energy to ensure our goals in constructing the first KRONOS MMR on the university's campus can become a reality," said Caleb Brooks, Professor and Donald Biggar Willett Faculty Scholar of Nuclear, Plasma and Radiological Engineering at The Grainger College of Engineering. "By submitting the Construction Permit Application to the NRC, we are taking the next step in signifying that the work will be done correctly and precisely. And we continue to look forward to the possibilities of what can become the most advanced nuclear research platform on any US campus." Application lodged to build microreactor at US university

Read More........→May 01, 2026