DIAMANTINA FRACTURE ZONE — Researchers conducted 32 deep-sea submersible dives in 2023 to survey the ocean floor. The findings, published in the journal Nature on June 10, identified what is currently the deepest and oldest known whale graveyard.

This graveyard extends along a 1,200-kilometer corridor at depths ranging from 13,800 to 23,000 feet. Recovered fossils date back 5.3 million years to the Early Pliocene, and a new whale species, Pterocetus diamantina, was identified among the remains. Researchers catalogued fossil remains from five beaked whale species and one baleen whale species, including the extinct beaked whale species Pterocetus benguelae.

Deep-sea researcher Xiaotong Peng described the scale of the discovery. "Discovering a necropolis of this scale was completely unexpected. The size of distribution, the depth and the age range were far beyond anything we had imagined." Peng said.

The largest active carcass documented is an Antarctic minke whale measuring 5 meters in length. Density extrapolation suggests that approximately 10 million whale carcasses exist across the surveyed area, with an estimated carbon content from soft tissue and lipids of 6.7 million tonnes. Marine organisms such as jellyfish, brittle stars, tubeworms, sea cucumbers, squat lobsters, and clams inhabit these carcass sites. Bacteria on the carcasses process bone lipids to produce hydrogen sulfide, which supports local food webs.

Study co-author Peng Zhou noted the thriving activity observed. "The vibrant ecosystems we saw offered a completely different perspective on this otherwise dark and cold ocean floor." Zhou said. Paleontologist Giovanni Bianucci said, "Studying the whale graveyards is important for understanding how life can adapt to such extreme conditions, not only due to the lack of light and oxygen but also to the incredibly high pressure."

Beaked whale jawbones have a high mineral density which aids their long-term preservation in deep ocean environments. A V-shaped geological formation in the region may also contribute to the concentration of drifting carcasses at the study site.