Discover Millions of Fossilized Whale Bones in Deep Sea ‘Graveyard’

Researchers have uncovered the world’s deepest whale graveyard located at seven kilometers in the southern Indian Ocean. Among the discoveries are remains of a new extinct beaked whale species along with fossils aged over 5 million years.

In early 2023, Peng Zhou and a team from the Chinese Academy of Sciences performed 32 dives in a manned submersible across over 1,200 kilometers undersea, exploring an area known as the Diamantina Zone.

This expedition is part of the Global Hadar Exploration Program, a significant initiative by Chinese scientists to investigate the deepest regions of Earth’s oceans, spanning depths from 6,000 to 11,000 meters. At these extreme depths, there is complete darkness, and life survives by consuming organic material that sinks from the surface or through chemosynthesis, a process relying on chemical energy.

The first fossil whale was detected at 7,002 meters in a part of the Diamantina region called the Dordrecht Strait, more than 1,100 kilometers southwest of Perth, Australia.

“Thanks to the submersible’s advanced lighting systems, we could observe tens of meters ahead even in the pitch-black ocean,” remarked Zhou. He found the experience “a little scary, yet incredibly fascinating.”

The researchers concluded there could be up to 760 whale carcasses per square kilometer, consisting of ancient remains and recent deaths—thus dubbing the area a “whale graveyard” as well as a “deep-sea fossil megasite.”

Recently deceased specimens included a 5-meter-long Antarctic minke whale (Balaenoptera bonaerensis), which is now nourishing an ecosystem of invertebrates, such as bone-eating insects and spider stars—many of which are believed to be new species and exist in astounding densities of up to 2800 individuals per square meter.

“It felt incredibly special,” stated Chow. “What we witnessed was a deep-time archive showcasing evolution and vibrant deep-sea life, home to millions of whales, some of which date over 5 million years. We honored this significant location with the utmost respect.”

The research team identified 485 active whale fall sites and fossil locations during their exploration. They successfully collected 43 fossil specimens dating between 120,000 years and 5.26 million years old.

Many of these recent fossils are from beaked whales representing two known species: beaked whales (Mesoprodon Boudoini) and southern beaked whales (Mesoprodone Rayadi).

So far, the research team has formally documented one new species, Pterocetus diamantinae. Team members believe they also collected fragmented specimens that may include additional undiscovered species, as noted by Giovanni Vianucci from the University of Pisa, Italy.

Peng Xiaotong, another researcher from the Chinese Academy of Sciences, explained that several factors contribute to the exceptional preservation of these fossils. Most of the remains consist of beaked whale snouts, which possess high-density bone structures that minimize physical deterioration and are less appealing to scavengers.

Over the last 5 million years, merely 0.05 to 0.55 millimeters of sediment has accumulated in this region, leading many of these bones to be coated in ferromanganese oxide, effectively insulating them from environmental exposure.

“Hence, the combination of dense bone structure, slow sedimentation, and mineral coatings has preserved these bones for over five million years,” stated Penn.

The researchers hypothesize that several factors have led to the high concentration of whale carcasses in the Diamantina — including the whales’ migratory paths and the V-shaped geomorphology of the area that accumulates carcasses.

Culum Brown, a professor at Macquarie University in Sydney not involved in the study, called the discovery a “remarkable finding.” “The density of whale-fall remains is extraordinary,” he commented.