A 5.3-million-year-old deep-sea whale necropolis in the Diamantina Zone

Abstract Whale falls are biodiversity oases at seabeds1,2,3,4,5,6, yet their record from the oceans has remained sparse and fragmentary6,7. Here we report the discovery of a vast whale necropolis in the Diamantina Zone (4,616- to 7,001-m depth), extending about 1,200 km along the sea floor of the southeastern Indian Ocean. This area has a deep and extensive accumulation comprising five modern natural whale-fall communities and 476 fossil cetaceans recorded. We show that carcasses host specialized communities dominated by brittle stars, bone-boring worms and chemosynthesis-based bivalves and that the fossil record in this area comprises both extant and extinct deep-diving beaked whales. Isotopic dating shows that whale falls in this region have occurred since at least 5.3 million years ago. These findings reshape the understanding of the limits and biogeography of whale-fall ecosystems and establish some deep sea floors as a fossil archive for tracing cetacean evolution over geological time. Main The deep sea is home to myriad life forms that have adapted to extreme environmental conditions. One of the most fascinating phenomena of the deep sea are whale-fall communities, whereby a whale carcass that sinks to the ocean floor1,2,3 initiates a highly idiosyncratic ecosystem in association with a variety of physiologically diverse organisms, thus providing crucial insights into the interplay of life and death in the ocean’s depths4,5,6,7. Although whale falls are abundant, with more than 70 sites documented across diverse ocean basins and depths6, their distribution remains patchy and only sporadically documented7. The species composition and diversity of whale-fall communities are strongly influenced by water depth and related environmental factors, such as temperature and hydrodynamic regime6,8,9. In contrast to deep-sea sites, shallow-water shelf whale falls generally yield different sets of taxa, indicating that highly specialized and species-rich whale-fall communities develop primarily in the food-limited setting of the deep ocean7,10,11,12,13. So far, however, most whale falls are found between some tens of metres to around 4,000 m water depth6,7, with the deepest example reaching 4,204 m in the southwest Atlantic Ocean14. The biogeography, evolutionary novelty and connectivity of deep-sea whale-fall communities remain poorly understood, first and foremost because of the paucity of data from abyssal and hadal depths7. The Diamantina Fracture Zone lies to the south of the Broken Ridge and Perth Abyssal Plain in the Indian Ocean, stretching about 1,200 km parallel to the Southeast Indian Ridge (Fig. 1). It formed as the Australian and Antarctic continents separated between 60 million and 50 million years ago15. The rough sea floor topology is the result of block faulting16. The deepest regions of the Diamantina Zone cluster in its northwestern section, most notably at the Dordrecht Deep, which reaches a maximum depth of 7,079 m as measured by the conductivity–temperature–depth sensor aboard the human-occupied vehicle (HOV) Fendouzhe in 2023. The Diamantina Zone has not been previously documented to be associated with any whale falls. Whale-fall biota From 8 February to 17 March 2023, using the Fendouzhe submersible capable of reaching depths of up to 11,000 m on board the R/V Tansuoyihao, we discovered extensive whale falls and fossils in the Diamantina Zone (Fig. 1 and Supplementary Video 1). During dive FDZ159, we first encountered whale fossils at a depth of 7,002 m, near the deepest point of the Dordrecht Deep. These fossils were found partially buried in soft surface sediments and lightly coated with black Fe–Mn oxides. Following the initial discovery, we conducted 32 dives to the sea floor, aiming at mapping the spatial distribution and extent of the whale falls and fossils, as well as identifying any associated whale-fall ecosystems. By doing this, we documented and collected samples from 485 whale-fossil sites and active whale falls (Fig. 2, Extended Data Tables 1 and 2 and Supplementary Table 1) from 1,200 km along the sea floor, representing an ecological landmark in the Diamantina Zone. The five active whale falls are in the sulfophilic stage (Fig. 2). Bones are covered with dense, whitish microbial mats and bone-boring worms Osedax, indicating prolonged residence on the sea floor. At 6,789 m water depth, the Dordrecht Deep beaked-whale carcass WF1, consisting of three elongated vertebrae, has the deepest active whale-fall community. The largest carcass encountered, the 5-m-long skeleton WF3, was identified as the Antarctic minke whale Balaenoptera bonaerensis through the highly diagnostic earbone morphology17 and a nearly complete mitochondrial genome (GenBank: PX519993). Across the five whale falls in the sulfophilic stage, the associated fauna are taxonomically broad, comprising 35 recognized macrofaunal taxa (more than 0.5 mm in size) documented from in situ imagery and collected specimens (Extended Data Table 1 and Extended Data Figs. 1 and 2). The macrofauna are dominated by annelids, crustaceans and molluscs, with further cnidarians and nematodes. Bone-eating worms, gastropods, vesicomyid bivalves and brittle stars dominate the megafauna (more than several centimetres in size), reaching local densities up to 2,840 individuals per square metre (Supplementary Table 2). Most recovered taxa may be new to science. Molecular data were obtained for 21 species, but only the vesicomyid bivalve Abyssogena southwardae could be confidently assigned to species level through barcoding comparison with GenBank records; all remaining species were identified at genus or family rank, integrating morphological data. Three chemosymbiotic bivalves (Adipicola sp., Abyssogena southwardae and Thyasiridae sp.) hosting different sulfur-oxidizing microbial symbionts (Extended Data Fig. 2) and two bone-eating worms (Osedax sp. 1 and Osedax sp. 2) form the core of these communities18,19. The observations at water depths of 5,609 m and 5,634 m of sea daisies (Asteroidea: Xyloplax sp.) provide, to our knowledge, the deepest evidence of this genus, as well as the first record on whale falls, expanding the habitat of Xyloplax beyond wood falls and hydrothermal vents20. Three brittle-star species (Ophiambix sp., Ophioscolecidae gen. et sp. and Silax sp.) recovered from the whale skeletons differ notably from the dominant trench-floor ophiuroid genera Ophiosphalma and Ophiuroglypha. The absence of whale-fall species in the background sediments indicates that these brittle-star assemblages are highly specialized and confined to organic-rich whale substrates. In addition, some whale falls, for instance, at depths of 5,115 m, 6,470 m, 6,570 m and 6,772 m, are in the final reef stage (Extended Data Fig. 3). The exterior of these skeletons is primarily inhabited by common hard-substrate megafauna, such as the stalked sea anemone Galatheanthemum profundale, the pedunculate sponge Caulophacus sp. and the sea star Freyastera sp. The different faunal composition of the studied whale falls may be attributable to their sites, successional stages or carcass sizes. Fossil whale fauna The palaeontological analysis of 43 recovered fossils from the Diamantina Zone led to the identification of five beaked-whale species and one baleen-whale species. Most of the beaked-whale specimens, primarily consisting of isolated rostra, were attributed to two living ziphiid species: the Andrews’ beaked whale, Mesoplodon bowdoini (Fig. 3a,b), and the strap-toothed whale, Mesoplodon layardii (Fig. 3c,d), both of which are known to inhabit the present-day southeastern Indian Ocean21. Diagnostic traits of M. layardii preserved in 14 specimens include a narrow, elongated, transversely compressed rostrum and a strongly pachyosteosclerotic vomer forming a prominent posterior bulge, a secondary anterior bulge and a midrostral dorsal depression in between (Fig. 3c,d and Extended Data Fig. 4a–g). Further matching traits, such as the shape of the prominential notch and maxillary tubercle and the size and position of the infraorbital and premaxillary foramina, further support this identification22. The seven rostra assigned to M. bowdoini are robust, moderately elongated and laterally compressed and provided with a single anterior vomeral bulge and a ventrally deflected apex, consistent with previous descriptions22 (Fig. 3a,b and Extended Data Fig. 4e–h). Three exceptionally well-preserved skulls were identified as belonging to the extinct genera Pterocetus and Izikoziphius, which were first described from fossils trawled from the sea floor off South Africa23. As for Pterocetus, this extinct relative of the modern Mesoplodon spp. and bottlenose beaked whales is characterized by distinctive wing-like expansions of the preorbital processes23. One Pterocetus specimen from the Diamantina Zone is referred to P. benguelae (Fig. 3h); the other represents a new species, Pterocetus diamantinae sp. nov. (Supplementary Note, Fig. 3e–g, Extended Data Figs. 5a,b and 6 and Extended Data Table 3). The single Izikoziphius cranium closely resembles the type species I. rossi (Fig. 3i and Extended Data Fig. 5e,f). Izikoziphius is a close relative of the extant Cuvier’s beaked whale but is recognized as a separate genus owing to the observation of a unique fossa on the premaxilla, a dome-shaped maxillary crest and a proportionally longer rostrum23. Baleen-whale fossils include a fairly well-preserved tympanic bulla of the sei whale, Balaenoptera borealis (Extended Data Fig. 5g–j) and several dilapidated, largely indeterminate cranial and postcranial remains of mostly balaenopterid mysticetes (Extended Data Fig. 5k–l). Dating of whale fossils To determine the ages of the fossils, we analysed 33 fossil bone specimens for their strontium isotope composition (87Sr/86Sr) (Fig. 4 and Extended Data Table 4). This method relies on comparing the isotopic signature preserved in the biominerals to the known historical record of seawater isotopes. Although this method is typically performed on compact dental tissues, the hyperdense bones of ziphiid rostra probably preserves a pristine Sr-isotope ratio24. Eight samples exhibited Sr-isotope ratios identical to modern seawater, indicating complete geochemical exchange after death. The remaining 25 samples, however, yielded 87Sr/86Sr ratios ranging from 0.709173 to 0.709029. When calibrated against the seawater 87Sr/86Sr curve25, these values correspond to ages between 0.12 Ma and 5.26 Ma. The fossil species Pterocetus bengulae and Izikoziphius rossi were found to be the oldest, with Sr-isotope average ages of 5.26 Ma and 2.44 Ma, respectively, whereas the extant species M. bowdoini (1.14–0 Ma) and M. layardii (1.20–0 Ma) are geologically younger. The oldest date indicates that whale-fall events have occurred in the Diamantina Zone since at least the Early Pliocene. Genesis of the whale necropolis On the basis of submersible observations, the density of whale remains reaches up to 759.5 individuals per square kilometre. The concentration of whale falls and fossils in the Diamantina Zone raises fundamental questions about the origin of this whale necropolis. Active whale-fall ecosystems were found thriving around both baleen and beaked-whale carcasses. The former group also includes the skeleton of an Antarctic minke whale, a circumpolar migratory species that is known to travel northward into the waters off southern Australia26,27. This epipelagic filter-feeder relies on krill in the upper ocean layers, mostly at depths not greater than 150 m (ref. 28). Most cetacean fossils consist of robust beaked-whale rostra, which have probably endured the destructive biostratinomic processes at play on the sea floor thanks to their hyperostotic structure. Among the few exceptions are poorly diagnostic bone fragments of baleen-whale skulls and the well-mineralized tympanic bulla of a sei whale. Like the Antarctic minke whale, the sei whale migrates seasonally into the southeastern Indian Ocean29. Observations of the diving behaviour of sei whales indicate feeding on copepods to depths of 50 m (ref. 30). Thus, the occurrence of remains of B. bonaerensis and B. borealis at such hadal depths is not related to deep-diving habits and rather is due to the carcasses sinking to the sea floor of this shared migratory corridor. The vast majority of the cetacean remains belong to two deep-diving ziphiid species: the strap-toothed and Andrews’ beaked whales, both of which are known to inhabit the southeastern Indian Ocean21,31,32. Beaked whales are specialized predators of deep-water squid and fish, foraging along steep continental slopes, submarine canyons, abyssal plains and trenches33. The Diamantina Zone, with its extreme depths ranging between 4,200 m and 7,000 m, complex V-shaped topography and abundant squid and fish resources as observed during our dives, provides an ideal deep-water foraging ground for beaked whales. Natural mortality, combined with the inherent risks of deep diving, probably contributes to the accumulation of beaked-whale remains in the sea floor of this zone. These beaked whales possess extraordinary physiological adaptations for deep diving, routinely reaching depths more than 1,000 m and holding their breath for more than a hour33,34,35. The maximum dive depth for beaked whales is estimated to be more than 3,000 m on the basis of lung collapse and oxygen storage34,35,36,37,38. Thus, foraging at depths exceeding 3,000 m would be too physiologically taxing for beaked whales and may heighten the risk of fatal exhaustion or decompression sickness37,38,39. Ultimately, the V-shaped topography of the Diamantina Zone may further contribute to this accumulation by funnelling and concentrating onto the sea floor the sinking carcasses caused by natural and accidental mortality. Critically, the ultra-low regional sedimentation rate close to the Diamantina Zone (Broken Ridge, 0–5 Ma, 0.05–0.55 cm kyr−1)40 implies a prolonged exposure of the skeletal remains at the sea floor: one that would probably last more than several hundred thousand years at least. On slopes or uplifted sea floor zones, skeletal remains may remain exposed for extended periods: up to 5.3 million years, according to our dating data. The fossilized remains we observed are almost exclusively beaked-whale rostra, some of which have the highest bone density and mineral content among extant vertebrates41. This high compactness probably inhibits rapid degradation, with long-term preservation on the sea floor being further enhanced by the progressive accumulation of ferromanganese oxides both within the bone matrix and on the outer bone surface. The latter process isolates the skeletal elements from the surrounding environment while increasing their robustness. For buried bones, additionally, authigenic carbonate precipitation during the organic degradation may also facilitate fossil preservation. The confluence of beaked whales’ deep-diving ecology, extreme foraging physiology, topographic focusing, an ultra-low sedimentation rate and early fossilization may explain the formation of this whale necropolis. Implications The discovery of whale-fall communities in the Diamantina Zone at depths exceeding 6,700 m establishes one of the deepest known whale-fall ecosystems in the ocean, extending the known depth range of such habitats by more than 2,500 m. Isolation, imposed by extreme depth, apparently has facilitated the development of a distinct, specialized whale-fall community dominated by species that may be new to science, as indicated by our molecular data (Extended Data Table 1). This not only expands our understanding of metazoan species richness in the deep-sea ecosystems but, given that we are still in the early stages of discovery of deep-sea whale-fall fauna7, also indicates that these species probably exhibit ecological novelty and represent cases of adaptive radiation. For instance, these whale falls share key ecological and evolutionary links with deep-sea cold seeps and hydrothermal vents6,19, including those in hadal trenches42,43, as evidenced by shared taxa such as chemosymbiotic bivalves (Adipicola, Abyssogena and Thyasiridae), gastropods (Phymorhynchus) and squat lobsters (Munidopsis). The results support the hypothesis that deep-sea whale falls act as evolutionary hotspots and biogeographic stepping stones for sulfide-dependent fauna in the deep ocean2,7,44,45,46,47. In the total survey area of 0.64 km2 (from 32 dives), five active whale falls were observed. This yields a density of 7.81 whale falls per square kilometre. Aligned along a northwest–southeast axis for 1,200 km, these falls may form a previously unrecognized ‘whale-fall community supercorridor’. This extensive biogeographic feature could have an important role in the dispersal, connectivity and evolution of deep-sea chemosynthetic communities across the Southern Indian Ocean. As beaked whales are known primarily from rare strandings, their abundance, distribution and ecology remain poorly understood overall48. Our discovery of an accumulation of skeletal remains of the two extant beaked-whale species Mesoplodon bowdoini and M. layardii provides an unparalleled source of information on these largely enigmatic cetaceans. Moreover, the investigated whale fossils, preserved for more than 5 million years, serve as an archive providing a direct, continuous record for tracing evolutionary trajectories. Comparative anatomical analysis of these remains can elucidate feeding behaviours, locomotion and ecological roles of deep-diving cetaceans. Thus, the Diamantina Zone necropolis constitutes a deep-sea fossil megasite: one that offers a window into the evolutionary history, palaeoecology and population dynamics of beaked whales from the Pliocene to the present day. Similar whale necropolises probably exist in other core beaked-whale habitats, such as South Africa23, the Iberian Peninsula49 and off the Crozet and Kerguelen islands50, as indicated by the recovery of abundant fossils by trawling, indicating that comparable hidden archives may be widespread in the global deep oceans. Systematic palaeontology Pterocetus diamantinae Bianucci & Collareta, sp. nov LSID. urn:lsid:zoobank.org:act:406FD05A-360B-4DD5-B146-4E355504AFD2. Holotype. FDZ182-R1a (deposited at the Hadal Museum, IDSSE-CAS, Sanya, China), partial skull including the rostrum and anterior neurocranium. Locality and age. Diamantina Zone sea floor, age unknown. Etymology. Named after the type locality. Diagnosis. Pterocetus diamantinae is a congener of P. benguelae based on the observation of notably wide and deep antorbital notches, anterolaterally expanded preorbital processes and premaxillary foramina that are located distinctly anterior to the antorbital notches; it differs from P. benguelae by having higher, medially located, anteroposteriorly long maxillary crests that extend onto the rostrum base and smaller premaxillary foramina. See full descriptions in the Supplementary Note. Methods HOV observations We conducted this investigation during the TS29-3 cruise (7 February to 18 March 2023) aboard the R/V Tan Suo Yi Hao, using the full-ocean-depth HOV Fendouzhe. Thirty-two HOV surveys were conducted on the sea floor along the trench axis, spanning more than 1,200 km and distributing relatively evenly from the western to the central and southeastern regions. The estimated trench-floor area is about 14,400 km2, calculated in Global Mapper 26.1 by delineating the areal extent of the trench bottom. The HOV video survey had a field of view about 5 m in width, calibrated using 10-cm laser scale points. The surveyed area was estimated from the view width and the sea floor transect length recorded by the in situ footage. Each transect was 2.4–5.5 km long (4.3 km on average), with a cumulative length of 127.72 km for all 32 dives, yielding a total surveyed area of about 0.64 km2. The diving map (Fig. 1) was generated using Global Mapper 26.1, with basemap data from Global Multi-Resolution Topography (GMRT) Synthesis (http://www.gmrt.org) under a CC BY 4.0 license51. Collecting and processing of whale-fall fauna samples Whale-fall fossil samples were collected using the submersible’s two hydraulically powered manipulator arms, operated by the submersible’s pilots, and stored in geological baskets. The whale-fall bones in the sulfophilic stage were collected using the arms and kept in the biobox. Some associated free-living whale-fall fauna species, including gastropods, squat lobsters and brittle stars, were collected using the slurp sampler mounted on the submersible. On retrieval of the submersible, the whale bones and associated specimens were immediately sorted, fixed and registered in the ship’s laboratory. For taxonomic purposes, specimens were preserved using either a 10% formalin or a 75% ethanol solution. Specimens for molecular analysis were preserved directly in −80 °C freezers. Examination of the whale-fall fauna and bivalve chemosymbionts Morphological identification was based on published literatures of deep-sea macrobenthos faunas, especially that reported from whale falls, cold seeps and hydrothermal vents. For further molecular examination, whale faunal tissues (up to 0.5 cm3) were subjected to DNA extraction, library preparation and metagenomic sequencing at Novogene Co., Ltd. Metagenomic sequencing was conducted using DNBSEQ-T10 (MGI) at Novogene to generate 2 bp × 150 bp pair-ended reads of about 50 Gb. Raw sequencing reads were qualified and assembled into contigs routinely. Assembled contigs were searched against the MetaCOXI database using the BLASTN program to extract mitochondrial 16S ribosomal RNA (rRNA) and cytochrome c oxidase I sequences52. The 18S and 28S rRNA gene sequences were predicted using rRNA_HMM53. To detect potential chemosynthetic symbionts in three bivalves, microbiome analyses were conducted to obtain metagenome-assembled genomes (MAGs) of associated microbials from the investigated bivalve gill tissues. The assembled metagenomes were subjected to genome binning, duplicate removal and quality evaluation and finally were annotated using GTDB-tk (v2.4.0)54 against the GTDB database R220 (ref. 55). The dominate symbiont MAGs are listed in Extended Data Fig. 3d according to relative abundances of all microbial reads from each host bivalve species. Density assessments Density assessments for the macro- and megafauna in whale-fall communities were conducted by analysing high-definition video recorded by the HOV’s dual camera system. Scale was provided by two parallel laser pointers (10 cm apart) visible in the footage, allowing the sizing of individual animals and communities (Supplementary Table 2). Each whale fall, including both the bone region (dominated by Osedax) and the surrounding sediment region influenced by the carcass (dominated by jellyfish or tubeworms), was measured as an entire whale-fall community by species. For three smaller whale falls (WF1, WF2, WF4), faunal density was analysed for the whole whale fall by directly counting the total number of faunal individuals observed. For two larger whale falls, 16 (WF3) or 6 (WF5) quadrats, each 4 dm2, were randomly selected and counted. In the latter case, the average density and the maximum density (the highest count observed in a single quadrat) were analysed. Sr isotopic dating for whale fossils Twenty-five fossil bone specimens were analysed for Sr isotopes at Nanjing FocuMS Technology Co. Ltd., and eight specimens were analysed at the Radiogenic Isotope Facility, University of Queensland. Samples (about 0.1 g) were fully digested in nitric acid. At Nanjing FocuMS Technology Co. Ltd., Sr separation was performed by means of a two-step column chemistry (HCl elution on Bio-Rad AG50W-X8 resin and then Milli-Q water elution on Sr-specific resin); at the Radiogenic Isotope Facility, the Sr purification protocol used in ref. 56 was adopted. Sr-isotope ratios of final solutions were determined using Nu Plasma MC-ICP-MS at both laboratories. Raw data were corrected for exponential mass fractionation by normalizing to 86Sr/88Sr = 0.1194. Periodical measurements of the Sr standard (SRM 987) were used for instrumental drift correction. Accuracy was monitored using United States Geological Survey reference materials (BCR-2, BHVO-2, EN-1), and the results agreed with published values57,58. Best-fit ages were calculated from the mean isotopic ratios using the seawater 87Sr/86Sr curve of ref. 24. Phylogenetic analysis The phylogenetic relationships of Perucetus diamantinae sp. nov. with the other Ziphiidae were investigated with the software PAUP (v.4.0a169)59, using the same morphological data matrix and assumptions as ref. 60, with the addition of the following new character, which shows only the derived state (1) in Pterocetus benguelae and P. diamantinae: antorbital notch: narrow, V- or U-shaped (0); deep and broad, bordered posterolaterally by an anteroventrolaterally expanded antorbital process (1). Homoplastic characters were downweighted using the method of ref. 61. The result of this analysis is presented in the Extended Data Fig. 6. Reporting summary Further information on research design is available in the Nature Portfolio Reporting Summary linked to this article. Data availability The original in situ images for the whale fossils and whale falls, and microbial MAGs for the dominant bivalve symbionts, are available on Science Data Bank (https://doi.org/10.57760/sciencedb.28830)62. The original images of 35 investigated whale-fall species are available on MorphoBank (https://morphobank.org/permalink/?P6064)63. Sixty-seven DNA barcoding gene sequences and one mitochondrial genome were deposited in GenBank (PX673207–PX673224; PX684580–PX684631; PX519993). References Woodward, S. P. A Manual of the Mollusca; or, Rudimentary Treatise of Recent and Fossil Shells (Weale, 1854). Smith, C. R., Kukert, H., Wheatcroft, R. A., Jumars, P. A. & Deming, J. W. Vent fauna on whale remains. Nature 341, 27–28 (1989). Squires, R. L., Goedert, J. L. & Barnes, L. G. Whale carcasses. Nature 349, 574 (1991). Fujioka, K., Wada, H. & Okano, H. Torishima whale bone deep-sea animal community assemblage—new finding by Shinkai 6500. J. Geogr. 102, 507–517 (1993). Dell, R. 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M.D. discloses support for the research of this work from the National Key R&D Program of China (grant no. 2025YFE0214500). X.S. discloses support for the research of this work from the National Natural Science Foundation of China (grant no. 42276090). Author information Authors and Affiliations Contributions X.P. and X.S. conceived the research. T.X., P.Z., K.T., M.D, Y.H., S.L. and X.P. performed the geochemical measurements. X.S., Z.G., D.L., S.M. and X.P. contributed the fauna data analysis. G.B. and A.C. performed fossil analyses. X.P., X.S., G.B., A.C., M.D. and P.Z. interpreted data. X.P., P.Z., X.S., J.L., T.W., S.D., M.T., H.L., W.X. and H.Z. conducted the cruise and collected samples. All co-authors participated in the discussion. X.P., X.S., G.B., A.C., P.Z. and M.D. wrote the manuscript with input of all co-authors. Corresponding author Ethics declarations Competing interests The authors declare no competing interests. Peer review Peer review information Nature thanks Stephen Godfrey, Craig Smith and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available. Additional information Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations. Extended data figures and tables Extended Data Fig. 1 In situ images showing selected fifteen macrobenthos observed on the whale falls in the Diamantina Zone. a, FDZ174. b, FDZ173. c, FDZ174. d, FDZ177. e, FDZ177. f, FDZ174. Each species is annotated with arrows and numbers. Cnidaria: 1, Ctenophore jellyfish; 2, sea anemone Ostiactis sp. Polychaeta: 3, abundant tubeworms Phyllochaetopterus sp. on around sediments; 4, tubeworm Nicomache sp.; 5, bone-eating worm Osedax sp. 1; 6, Osedax sp. 2 with four pinnule-bearing palps (in detail); 7, scale worm Polynoidae sp.; 8, Phyllodocida Nereis sp. Mollusk: 9, gastropod Phymorhynchus sp. 1; 10, bivalve Adipicola sp. Echinodermata: 11, brittle star Ophiambix sp. Crustacea: 12, sea daisy Xyloplax sp. 13, squat lobster Munidopsis sp.; 14, amphipods Lysianassidae sp. and Stegocephalidae sp. (as white spots); 15, sea spider Nymphon sp. See full species list in Extended Data Table 1. Extended Data Fig. 2 Left shells of three chemosymbiotic bivalve species recovered from the investigated whale falls. a, Abyssogena southwardae, dive FDZ178. b, Adipicola sp., FDZ178. c, Thyasiridae sp. FDZ174. d, Metagenomic analysis showing the dominant symbionts inhabiting the gill tissues of the bivalve specimens shown in a, b and c. Red values indicate relative evolutionary divergence. *The Sulfurovum symbiont exhibits high intraspecific divergence and was therefore assembled into three low-quality MAGs (metagenome-assembled genomes). Their combined relative abundance reaches up to 71%, representing a typical symbiotic pattern. These MAGs are available from Science Data Bank (https://doi.org/10.57760/sciencedb.28830)62. Scale bar, 5 mm, all images at the same magnification. Extended Data Fig. 3 In situ images of whale falls in reef stage. a, Partially destroyed cranium and articulated mandible of a baleen whale. b, Articulated lumbar and caudal vertebrae of a beaked whale. c, Disarticulated skeleton of an indeterminate cetacean. d, Fragmentary vertebrae of an indeterminate cetacean. e, Fragmentary cranial bones of a baleen whale. The exterior of these skeletons is mainly inhabited by common hard-substrate megafauna, such as the stalked sea anemone Galatheanthemum profundale (yellow arrows) and the sea star Freyastera sp. (orange arrows). Scale bars, 20 cm. Extended Data Fig. 4 Fossil crania of Mesoplodon layardii and Mesoplodon bowdoini (Ziphiidae) from the Diamantina Zone. a-d, Mesoplodon layardii, FDZ184-R1a (a, b) and FDZ179-R1a (c, d). e-h, Mesoplodon bowdoini, FDZ180-R1a (e, f) and FDZ182-R4a (g, h). a, c, e, g, dorsal views. b, d, f, h, lateral views. Dotted lines indicate uncertain sutures. Oblique lines indicate major break surfaces. Scale bars, 20 cm. The superimposed silhouettes of M. layardii and M. bowdoini were redrawn here based on photographs of their extant conspecific skull specimens MM002133 and MM002655, respectively. Both extant skulls are held at the Museum of New Zealand Te Papa Tongarewa (https://collections.tepapa.govt.nz). Extended Data Fig. 5 Fossil cetaceans from the Diamantina Zone. a-f, Crania of Ziphiidae. a,b, Pterocetus diamantinae sp. nov., FDZ182-R1a, holotype. (c,d) Pterocetus benguelae, FDZ186-R3a. e, f, Izikoziphius rossi, FDZ163-R7a. g-l. Cranial remains of Mysticeti. g-j, Right tympanic bulla of Balaenoptera borealis, FDZ185-R5a. k, l, Right zygomatic process of squamosal of Balaenopteridae indet, FDZ164-R1a. a, j, Ventral views. b, g, l, Dorsal views. c, f, Anterior views. d, e, i, k, Lateral views. h, Medial view. Dotted lines indicate uncertain sutures. Oblique lines indicate major break surfaces. Scale bars, 10 cm. Extended Data Fig. 6 Strict consensus tree of 270 most parsimonious trees describing the phylogenetic relationships of Pterucetus diamantinae sp. nov. among Ziphiidae. The tree has a length of 233, a Goloboff fit of −44.04, an ensemble consistency index (CI) of 0.40, and an ensemble retention index (RI) of 0.80. Supplementary information Supplementary Information (download DOCX ) Supplementary Note. Supplementary Tables (download XLSX ) Supplementary Table 1. Collecting information of all investigated whale fossils and whale falls. A total of 485 whale-fall sites or fossil assemblages were documented using an HOV high-definition camera system from the sea floor of the Diamantina Zone. The original dataset is available on Science Data Bank (https://doi.org/10.57760/sciencedb.28830)62. Supplementary Table 2. Statistics on the inhabiting density of the faunal species associated with the investigated active whale falls. The table presents the faunal density calculated for countable taxa that could be identified from in situ HOV footage and photographs. Supplementary Video 1 (download MOV ) Whale-fall and whale-fossil underwater video clips. Underwater video footage showing visual documentation of the modern whale-fall communities and fossil assemblages recorded from the sea floor of the Diamantina Zone. 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To view a copy of this licence, visit http://creativecommons.org/licenses/by-nc-nd/4.0/. About this article Cite this article Peng, X., Zhou, P., Song, X. et al. A 5.3-million-year-old deep-sea whale necropolis in the Diamantina Zone. Nature (2026). https://doi.org/10.1038/s41586-026-10546-z Received: Accepted: Published: Version of record: DOI: https://doi.org/10.1038/s41586-026-10546-z