Fossil skulls of three beaked whales recovered from the seabed. The image shows two extinct species of beaked whale, Pterocetus diamantinae (new species to science, at the top) and Izikoziphius rossi (the second skull), as well as the Andrews' beaked whale Mesoplodon bowdoini (two skulls at the bottom), a still extant species. Global TREnD/IDSSE/Disclosure A vast whale cemetery hidden deep in the Indian Ocean has revealed a story spanning millions of years. Researchers from the Chinese Academy of Sciences discovered an underwater necropolis with fossils and carcasses distributed over about 1,200 kilometers in the Diamond Zone, a region between Australia and Antarctica. The study, published in the scientific journal "Nature", identified 485 sites containing cetacean remains and five still active whale falls — the name given to the carcasses that sink to the ocean floor and start to support entire communities of organisms. The discovery may represent the deepest and most extensive known accumulation of whale fossils and carcasses ever recorded, as well as offering an unprecedented window into the evolution of these marine mammals over the past 5.3 million years. What is a "whale fall" When a whale dies and sinks, its carcass carries a huge amount of organic matter to the bottom of the sea. In environments extremely poor in food, these remains function as true biological oases. Now on g1 The researchers found five active communities associated with carcasses located between 4,625 and 6,789 meters deep. Some of them were dominated by bone-boring worms, snake stars, molluscs and bacteria capable of obtaining energy through chemical processes, without depending on sunlight. In total, 35 groups of macrofauna were documented. According to the authors, most of the species found may be new to science. Furthermore, scientists recorded organisms at depths much greater than those previously known for this type of ecosystem. The whale falls in Zona Diamantina extend the known limit of these habitats by more than 2,500 meters. Recovery of fossilized whale bones using the manipulator arm of the Chinese submersible Fendouzhe on the seabed of the Diamantina Zone. Global TREnD/IDSSE/Disclosure Fossils up to 5.3 million years old To determine the age of the remains found, the team analyzed the isotopic composition of 33 fossils. The results indicated ages between approximately 120 thousand years and 5.26 million years. The oldest fossil belongs to an extinct beaked whale of the genus Pterocetus. According to the researchers, this shows that whale falls have occurred in the region since at least the beginning of the Pliocene, a time when the global climate was significantly warmer than today. The team also identified fossils of modern species of beaked whales that still inhabit the Indian Ocean, suggesting impressive ecological continuity over millions of years. Map of the "whale cemetery" located under study Disclosure/Nature New species of extinct whale Among the finds is a new species called Pterocetus diamantinae. The fossil consists of part of the skull of an extinct beaked whale found at a depth of almost 6,900 meters. Anatomical analysis showed sufficiently distinct characteristics to classify it as a previously unknown species. The discovery expands knowledge about the evolution of beaked whales, one of the most enigmatic groups of cetaceans. Why did so many whales die there? The extraordinary concentration of whale remains led researchers to investigate the origin of the necropolis. The main hypothesis involves the combination of several factors. The region is located on a route frequented by migratory whales and is home to favorable conditions for feeding beaked whales, which perform some of the deepest dives in the animal kingdom. Additionally, the valley-shaped topography can act as a natural trap for sunken carcasses. Another important factor is the region's extremely low sedimentation rate, which allows bones to remain exposed and preserved for hundreds of thousands or even millions of years. According to the authors, the combination of these elements can explain the formation of the enormous fossil deposit. Impact of the discovery Scientists claim that the necropolis transforms the understanding of deep-sea ecosystems. Whale falls can act as connection points between extreme habitats such as hydrothermal vents and cold seafloor exudations, helping specialized organisms disperse over long distances. Furthermore, the site constitutes a rare natural archive of the evolutionary history of beaked whales. Because these animals are rarely observed alive and often known only from occasional strandings, preserved fossils offer a unique opportunity to reconstruct their evolution, distribution, and ecology over millions of years. How was the study carried out? The researchers carried out 32 dives with the manned submarine Fendouzhe between February and March 2023, covering around 1,200 kilometers of the Diamantina Zone. 485 sites containing fossils or carcasses were recorded and samples were collected for biological, anatomical and geochemical analyses. The age of the fossils was estimated by strontium isotope dating on 33 specimens. Among the strengths are the unprecedented access to depths of up to 7,000 meters and the combination of paleontology, ecology and genetics. As a caveat, only a small fraction of the total area was directly observed, and the hypotheses to explain the concentration of whales in the region remain inferential, without direct proof.