The three sites at the heart of the study — Haqel, Hjoula and Nammoura — are Konservat-Lagerstätten, a technical term for fossil deposits of exceptional preservation. They sit within Cenomanian limestones, rocks deposited roughly 100 million years ago during the middle portion of the Late Cretaceous, when Lebanon lay beneath a warm shallow sea on the northern rim of the Gondwana super-continent. Cenomanian limestones cover about 40 percent of Lebanon’s territory, but only a handful of levels within them contain the spectacular fish faunas. Despite centuries of study, the stratigraphic assignment of the fossil-bearing level has remained controversial, with different researchers proposing ages ranging from the early Cenomanian to the Turonian, depending on which index fossils they trusted.

To resolve the dispute, the research team measured detailed stratigraphic sections at each of the three quarries and processed the limestones for their microscopic fossil content. One hundred petrographic thin sections were manufactured and examined, revealing a rich inventory of benthic and planktonic foraminifera — single-celled organisms whose shells are among the most reliable timekeepers in the Cretaceous rock record. The benthic assemblages included families such as Orbitolinidae, Nezzazatidae, Cuneolinidae and Gavelinellidae, while the planktonic component was dominated by hedbergellids, with rarer rotaliporids and heterohelicids. Abundant calcispheres, most likely resting stages of planktonic algae, riddled nearly every sample, alongside rare dasycladalean algae, bryozoans, ostracods, echinoderm fragments and bone debris.

The microfossils delivered a clear verdict. The presence of the larger benthic foraminifer Conicorbitolina conica together with the planktonic species Favusella washitensis within the Haqel and Hjoula Lagerstätten points to a middle Cenomanian age. Orbitolina, irrespective of the species involved, is particularly important because it provides a reliable constraint indicating an age no younger than the middle Cenomanian. But here the story takes a twist that has left palaeontologists genuinely puzzled: the macrofossil assemblages — echinoids and ammonites found above and below the fish beds — stubbornly refuse to agree. Well-preserved ammonites described in recent work from Hjoula, including Eucalycoceras rowei and Eucalycoceras pentagonum, characterise the lower Late Cenomanian Calycoceras guerangeri Zone, suggesting the fish layers are slightly younger than the foraminifera imply. The discrepancy between ammonite and foraminiferal dating remains an open question, one the authors suggest may only be settled by future fieldwork that pins new ammonite finds to precise positions within the measured sections — a difficult task in a region so fractured by tectonics that Saint-Marc warned decades ago it would demand an extremely close study.

The team also tested whether geochemistry could break the deadlock. Carbon and oxygen isotope ratios were measured on carbonate powders from all three outcrops, reacted with phosphoric acid and analysed on a Delta V Plus mass spectrometer in Germany with a reproducibility of ±0.04 per mil. The result: a fairly homogeneous distribution with no significant shifts across facies, meaning the isotope data could not be used as a stratigraphic tool. Elemental mapping with a field-emission scanning electron microscope did, however, reveal a sharp transition in a Haqel sample from a layer rich in magnesium to one deprived of the element — a subtle chemical fingerprint of changing water conditions that may reward future investigation.

The palaeoenvironmental reconstruction is where the study turns genuinely viral in its implications. The microfacies tell of small, quiet basins: thin-bedded muddy wackestones packed with calcispheres and small planktonic foraminifera, with mud-dwelling foraminifers such as Istriloculina indicating a low-energy decantation environment. Crucially, the rich benthic foraminiferal assemblage typical of the Cenomanian shelf is almost entirely absent from the sections — it appears only in very rare thin laminae, probably transported from shallower settings by small distal turbidites or tempestites, underwater avalanches dragging shelf material down into the basins. The planktonic assemblage is dominated by small hedbergellids and Favusella washitensis, species characteristic of warm, shallow epicontinental and marginal seas, while the rarer keeled genera Thalmanninella and Praeglobotruncana, generally deeper-dwelling forms, indicate only moderate water depth. The dominance of epicontinental species suggests the basins lay in waters no deeper than about 100 metres.

Then there is the fish fauna itself — and this is where the Lebanese sites leave every other Mesozoic locality in the dust. The updated inventory compiled from fieldwork and literature counts 93 species at Haqel, 72 at Hjoula and 40 at Nammoura, and taken together the three assemblages comprise 141 ray-finned fish species. That is nearly double the 74 species of the famous Late Jurassic Solnhofen Archipelago in Germany, and equal to the 74 species of Monte San Giorgio on the Italian-Swiss border — despite both of those celebrated localities spanning longer time periods and wider geographic ranges. The Lebanese Cenomanian assemblages therefore represent the richest ray-finned fish fauna ever reported from the Mesozoic and one of the richest of the entire Phanerozoic. Only the Eocene deposits of Monte Bolca in Italy, with roughly 250 described species, surpass them. New taxa are still being excavated at a rate of one to five per year, and the past two decades alone have seen described species increase by 20 percent at Haqel, 24 percent at Hjoula and 33 percent at Nammoura.

Many of the new discoveries belong to pycnodonts, a group of deep-bodied, crushing-toothed fish ecologically analogous to modern triggerfish — and the Lebanese pycnodonts are spectacularly strange. Two-thirds of the pycnodont genera from Haqel and Hjoula belong to families with morphologies unique in the entire long history of the clade, restricted to this single window of Cenomanian time and space. Gladiopycnodontids sported dorsal spines, cephalic and nuchal horns and an enlarged pectoral girdle; gebrayelichthyids had an extremely deep and short silhouette; coccodontids carried armoured trunks and rostrums reminiscent of pipefish. The authors suggest the gladiopycnodontids and gebrayelichthyids were suction feeders on small planktonic crustaceans, while other pycnodonts crushed shelly invertebrates near the bottom. The reconstructed food web also includes schooling planktivores such as Armigatus and Scombroclupea, often preserved in monospecific mass-mortality layers; demersal beryciforms and myctophiforms feeding on invertebrates and small fish; and apex piscivores among the aulopiformes and the ichthyodectiform Eubiodectes. Intriguingly, several clades now abundant in deep waters, such as beryciformes and aulopiformes, first diversified in shallow Cretaceous seas before migrating downward, probably driven out by new competitors.

So what killed and concentrated all this life? For decades the standard explanation blamed toxic algal blooms — the abundant calcisphaerulids in the sediments were taken as evidence of plankton blooms that poisoned the water. But the authors point out a paradox: calcisphaerulid-rich sediments are common worldwide, contemporary with the Lebanese deposits or not, and they are almost never associated with such rich fossil faunas. The blooms alone cannot explain the sites. Instead, the team proposes that the topography was the decisive factor. Hückel described the fish beds as accumulating in deep holes in the seafloor — roughly 600 metres across and 150 metres deep at Haqel — and the new study interprets these structures as submerged sinkholes, small cup-shaped depressions of probable tectonic origin in an actively deforming region. The model is strikingly supported by modern analogues: off the Florida coast, researchers recorded an aggregation of spawning barbfish, Polymixia lowei, inside a sinkhole — a fish phylogenetically related to genera found at Hjoula and Haqel — while shallower sinkholes off Brazil are documented biodiversity and productivity hotspots. In the Lebanese scenario, the water column above each sinkhole offered favourable living conditions, but the bottom was anoxic and azoic. When fish and other animals perished, perhaps from algal blooms or simply died and sank, their carcasses settled onto a seafloor with no scavengers and no currents to dismember them, and were buried in fine mud with smooth, undisturbed deposition.

The sites still guard their secrets. Haqel and Hjoula, separated by only 3.7 kilometres, share roughly 44 percent of their species, while Nammoura overlaps by only about 20 percent with the other two — figures that have remained remarkably stable even as the species counts have grown. Whether the differences between the faunas reflect real environmental distinctions or collection bias remains undecided, and the exact contemporaneity of the Lagerstätten is still unresolved. But the new synthesis makes one thing clear: the Lebanese Cenomanian sites owe their unmatched richness to a rare conspiracy of circumstances — shallow warm seas teeming with diversifying fish, small tectonic traps on the seafloor, anoxic bottoms that froze out scavengers, and fine carbonate mud that entombed everything from plankton to pterosaurs. It is a combination that has occurred perhaps nowhere else in the Mesozoic rock record, and it is why slabs of Lebanese limestone, split open for sixteen centuries, still stop scientists — and everyone else — in their tracks.

Subject of Research: Biostratigraphy and palaeoenvironments of the Upper Cretaceous fossil fish Konservat-Lagerstätten of Lebanon

Article Title: Biostratigraphy and palaeoenvironments of the Upper Cretaceous fossil fish Konservat – Lagerstätten of Lebanon

Article References: Maksoud, S., El Hossny, T., Cavin, L., Abi Saad, P., Azar, D., Piuz, A., & Samankassou, E. (2026). Biostratigraphy and palaeoenvironments of the Upper Cretaceous fossil fish Konservat-Lagerstätten of Lebanon. Swiss Journal of Palaeontology, 145, 433-474. https://doi.org/10.3897/sjp.145.181847

Image Credits: AI Generated

DOI: 10.3897/sjp.145.181847

Keywords: Lebanon, Haqel, Hjoula, Nammoura, Cenomanian, Konservat-Lagerstätten, fossil fish, foraminifera, biostratigraphy, palaeoenvironment, sinkholes, pycnodonts

Bothriolepis is, by any measure, a superstar of Devonian paleontology. With 97 recognized species, it is the most speciose genus among the antiarchs, a highly specialized group of placoderms, the jawed stem gnathostomes that dominated the waters of the Silurian and Devonian worlds. Antiarchs are instantly recognizable by their heavy bony armor and paired pectoral appendages that resemble jointed arms encased in plates. Sixty-five genera of antiarchs have been reported so far, and Bothriolepis stands out not only for its diversity but also for its cosmopolitan distribution, with fossils recovered from every major Devonian landmass. Yet despite this fame, many of its species remain known from frustratingly incomplete material.

B. yunnanensis is a case in point. Liu described the species in 1962 based on an anterior median dorsal plate and an incomplete posterior median dorsal plate collected from a small hillside about one kilometer north of Zhanyi Old Town, now the Taojiashan area of the Zhanyi urban district. These plates come from the Middle Devonian Shangshuanghe Formation, which is characterized by yellow to green fine-grained sandstones yielding abundant disarticulated fish plates. Although the species has been frequently cited in stratigraphic studies over the decades, no additional material had ever been described, leaving its morphology and phylogenetic position poorly understood. The new study designates the anterior median dorsal plate as the lectotype and the posterior median dorsal plate as the paralectotype, formally anchoring the species to a single anatomical reference point.

Everything changed with continuous fieldwork that began in 2020. The research team collected numerous new specimens from the type locality and from two sites in the Zhujiangyuan area, designated Zhujiangyuan Locality 1 and Zhujiangyuan Locality 4. The haul includes an articulated head shield, a head shield articulating with the trunk armor, pectoral appendages, and many disarticulated plates. All specimens are housed in the Institute of Vertebrate Paleontology and Paleoanthropology of the Chinese Academy of Sciences in Beijing. The fish-bearing layer at Zhujiangyuan Locality 1 belongs to the Shangshuanghe Formation of Eifelian age, while the layers at Zhujiangyuan Locality 4 belong to the Xichong Formation of Givetian age. This new fossil horizon extends the temporal range of B. yunnanensis from the Eifelian to the entire Middle Devonian, a significant expansion for a species previously known from a single horizon.

The Devonian strata of the Qujing area are exceptionally well exposed and subdivided into a clear succession of formations, from the Lower Devonian Xishancun, Xitun, Guijiatun, and Xujiachong formations, through the Lower to Middle Devonian Chuandong Formation, the Middle Devonian Shangshuanghe and Xichong formations, and up to the Upper Devonian Zaige Formation. In the Zhujiangyuan area, the Guijiatun, Xujiachong, and Chuandong formations are absent, and the Middle Devonian units sit directly between the underlying Lower Devonian Xitun Formation and the overlying Upper Devonian Zaige Formation. At Taojiashan, the limited fish-bearing Middle Devonian is strictly controlled by faults, but lithological characteristics and available biostratigraphic evidence assign the lectotype horizon to the Shangshuanghe Formation.

The technical heart of the study lies in the detailed description of the newly recovered material, including high-resolution computed tomography of a well-preserved head shield. The head shield of B. yunnanensis is wider than long, with a breadth to length ratio of 1.35 in the largest specimen, which measures 77 millimeters across. The orbital fenestra, the window for the eyes, is short and wide with a breadth to length ratio of 2.1, and its anterior margin is concave while the posterior margin is straight. The premedian plate is trapezoidal, the lateral plate is the largest plate of the head shield, and the postpineal plate is wider than long, shaped as a posteriorly pointing rounded triangle. The nuchal plate is roughly heptagonal, and its anterolateral margin is obviously shorter than its posterolateral margins, a subtle but diagnostic feature.

The CT scan of specimen IVPP V34361, performed on a GE v|tome|x micro-tomography scanner at 240 kV and 110 mA with a resolution of 59.963 micrometers, produced 3,979 slices that were segmented and reconstructed in three dimensions. The visceral surface of the head shield revealed a trifid preorbital recess with three well-developed extensions, a developed postorbital process, a well-developed paramarginal crista in the otico-occipital depression, and a low and broad transverse nuchal crista. Crucially, the large unpaired insertion fossa for levator muscles lies immediately behind the transverse nuchal crista, and there is no median occipital crista. This absence of the median occipital crista is one of the key characters that unites B. yunnanensis with a distinctive clade of Bothriolepis species.

The trunk armor tells an equally detailed story. The anterior median dorsal plate is hexagonal with anterior and posterior margins nearly equal in width, and its breadth to length ratios range from 0.82 to 0.91 across the studied specimens. The ratio between the breadth of the anterior margin and the maximum breadth of the plate ranges from 0.43 to 0.53, well below the 0.55 threshold that separates B. yunnanensis from its closest Chinese relatives. The levator fossa is a broad and short inverted triangle occupying one-third of the plate length, and the anterior ventral pit lies posterior to the confluence of the postlevator thickening and postlevator cristae. The posterior median dorsal plate is pentagonal with an arc-shaped posterior margin lacking a posterior corner, and the ventral median groove on its ventral side is absent. The pectoral appendage is remarkably slender, with a proximal segment reaching 87.2 millimeters in length but only 19.4 millimeters in breadth in the largest specimen, an elongation ratio of 4.49, and short, blunt, closely arranged lateral spines run along its margin.

With this comprehensive morphological dataset in hand, the team conducted a parsimony phylogenetic analysis based on the data matrices of previous studies, adding B. yunnanensis as a new taxon and one additional character. The analysis yielded 12 most parsimonious trees, each with a length of 385 steps, a consistency index of 0.213, and a retention index of 0.498. The results place B. niushoushanensis at the most basal position within the genus, while B. yunnanensis, B. zhujiangyuanensis, B. sinensis, and B. kwangtungensis from China form a clade with some Bothriolepis species from Laurussia and Kazakhstania. This clade is supported by three synapomorphies: the absence of the median occipital crista, a slender proximal segment of the pectoral appendage, and a long posterior pit line. The trifid shape of the preorbital recess appears very low in the phylogeny, consistent with recent computerized analyses but contradicting older interpretations.

The paleogeographic implications are perhaps the most thrilling part of the story. During the Devonian, the South China and Kazakhstania blocks were separate terranes, and the presence of shared Bothriolepis clades between China, Kazakhstania, and Laurussia suggests faunal connections among these regions. The new analysis further corroborates the paleogeographic proximity between the South China and Kazakhstania blocks, reinforcing a picture of Devonian seas and coastlines that were far more connected than their modern geography might suggest. Meanwhile, B. tungseni from China emerges as the sister taxon of B. dorakarasugensis from Siberia, adding another thread to this transcontinental web. For a species that sat in taxonomic limbo for more than sixty years, B. yunnanensis has now become a bridge between continents, a reminder that even the most fragmentary fossils can hold the keys to understanding how life spread across an ancient planet.

Subject of Research: Paleontology

Article Title: Morphology and phylogeny of Bothriolepis yunnanensis ( Placodermi , Antiarcha ) from the Middle Devonian of China

Article References: Yan, Y., Zhao, W., Luo, Y., Yu, H., & Zhu, M. (2026). Morphology and phylogeny of Bothriolepis yunnanensis (Placodermi, Antiarcha) from the Middle Devonian of China. Swiss Journal of Palaeontology, 145, 535-551. https://doi.org/10.3897/sjp.145.179243

Image Credits: AI Generated

DOI: 10.3897/sjp.145.179243

Keywords: Bothriolepis, placoderm, Devonian, antiarch, paleontology, China, fossil fish, phylogeny, Morphology, yunnanensis, Placodermi, Antiarcha

Protosphyraena belongs to the Pachycormiformes, an extinct order of Mesozoic ray-finned fishes that achieved extraordinary ecological diversity during the Jurassic and Cretaceous. The group ranged from gigantic suspension feeders to fast-swimming pelagic hunters, and Protosphyraena represents the most derived macropredatory form among them. Its most distinctive features are an elongate, sword-like rostrum and pectoral fins armed with a serrated leading edge, adaptations that made it one of the most recognisable predators of the Cretaceous seas. The genus is best known from the Upper Cretaceous of North America and England, but its Early Cretaceous origins have remained frustratingly obscure, largely because most specimens consist of isolated teeth, fin fragments and rostra.

The problem at the heart of the new study is a taxonomic tangle that has persisted for nearly twenty years. In 2007, palaeontologist Benjamin Kear described a partial skull from the Albian Toolebuc Formation of Australia as Australopachycormus hurleyi, an endemic pachycormiform genus. Several subsequent authors questioned this endemism and suggested that Australopachycormus was simply a species of Protosphyraena, but direct comparison proved impossible. The Northern Hemisphere Albian record consisted only of isolated pectoral fins and teeth, while diagnostic cranial material existed solely in Australia. With no anatomical overlap between coeval specimens from the two hemispheres, the debate remained frozen.

That changed in autumn 2025, when researchers discovered the anterior parts of jaws weathering out of grey clayey marls of the Khadzhalmakhi Formation near the Chindircero ski resort in Dagestan. Subsequent excavations recovered the remainder of the skull, a specimen catalogued as SGM-2169-1 and measuring approximately 37 centimetres in preserved length. The specimen was donated to the Vernadsky State Geological Museum in Moscow and prepared by sandblasting. Two fragments of pectoral fins, collected in the 2010s from a nearby locality, complete the Dagestan material. The fish layer from which the skull was extracted corresponds to the uppermost Albian, the Stoliczkaia dispar ammonite biozone and nannofossil subzone NC10A, making it one nannofossil subzone younger than the Australian specimens.

The anatomical detail preserved in the new skull is what makes the comparison possible. The premaxilla bears seven alveoli with six large blade-like teeth in functional position, tightly packed, plus at least four smaller teeth further back. The maxilla carries a single row of very small teeth that become so reduced posteriorly that they are visible only from the internal side of the bone. The dentary is elongate and slender, with a height-to-length ratio of approximately 0.125, and its teeth are small, conical and oriented perpendicular to the oral margin, with no additional lateral marginal teeth. The parasphenoid is covered with small shagreen-like denticles, and the posterior neurocranium preserves paired opisthotics, prootics, exoccipitals and a large wedge-shaped basioccipital, with foramina for the facial, glossopharyngeal and vagus nerves.

When the researchers compared these features with the type species Protosphyraena ferox from the Cenomanian-Turonian of England and with the Australian P. hurleyi, the similarities were overwhelming. The Dagestan skull shares with both taxa an elongated skull with a high dentary length-to-height ratio, moderately small perpendicular dentary teeth, the absence of additional lateral dentary denticles, and six large premaxillary teeth in functional position. The specimen is also very close in size to one of the Australian P. hurleyi specimens, QMF49220, for which individual bone measurements exist: the premaxilla measures 8.76 centimetres in the Australian specimen and 9.2 centimetres in the Dagestan skull, while the maximum depth of the maxilla is 2.06 versus 2.3 centimetres.

The only autapomorphy originally proposed for Australopachycormus, rostrodermethmoid teeth directed obliquely backwards, has been shown to be inconsistent, since the same condition occurs in several Protosphyraena species, including the type species P. ferox. Other characters proposed by Kear, such as a single row of dentary teeth, are also observed in P. ferox. The researchers found small partially resorbed alveoli in the posterior coronoid of a type-series specimen of P. ferox, suggesting that the difference in coronoid dentition between the two taxa may simply reflect ontogeny, especially given that known P. ferox specimens are nearly twice as large as those of P. hurleyi. At present, the only clear differences between P. ferox and P. hurleyi appear to be geographic and stratigraphic occurrence, leading the authors to suggest that the two species may be potential synonyms, probably representing an anagenetic lineage.

Additional evidence came from previously undescribed material in the Albian Gault Formation of England, studied in the collections of the Sedgwick Museum in Cambridge and the Natural History Museum in London. Among the Gault specimens, one premaxilla is highly similar to those of P. ferox, P. hurleyi and the Dagestan skull, and the only known rostrum from the formation closely resembles that of P. ferox, although it appears more slender with less pronounced ornamentation, potentially indicating the condition present in the Australian P. hurleyi. The Gault material also reveals that several pachycormiform taxa coexisted in the late Albian of Western Europe: two distinct hypural plate morphotypes, pectoral fins with different serration patterns, and two fragmentary fins lacking serration and leading-edge ornamentation that may belong to a more basal protosphyraenid or a derived asthenocormine such as Rhinconichthys.

The biogeographic implications are profound. The endemism hypothesis had spawned a claim that Australia was the source region for longirostrine protosphyraenids, with the first billed pachycormiforms evolving there and subsequently spreading across the Tethys Ocean to populate the Northern Hemisphere. But this is difficult to reconcile with the known evolutionary history of the group, since the putative Late Jurassic ancestor of Protosphyraena, Orthocormus, is known exclusively from Europe. The new findings contradict the assumed endemism of Australian protosphyraenines and the hypothesised provincialism of large marine vertebrates between the hemispheres during the Albian. This is not unexpected, the authors note, given that during the Albian both the Caucasus and the Australian Eromanga Sea were connected with the Tethys Ocean, providing dispersal corridors for wide-ranging pelagic predators.

The study also highlights how much remains to be learned about this tangled genus. Differences in pectoral fin serration patterns among Australian specimens suggest that several Protosphyraena species may have coexisted in the Albian of Australia, mirroring the diversity of fin morphotypes in the English Chalk. Historically, most isolated protosphyraenine remains from the English Chalk have been attributed to P. ferox by default, a practice the authors say clearly requires revision. The researchers point to undescribed material in the Kronosaurus Korner Museum in Richmond, Queensland, as potentially helping to unravel the knot of fragmented and non-overlapping specimens. For now, the Dagestan skull stands as the first articulated Protosphyraena skull from the Albian of the Northern Hemisphere, and as decisive evidence that the endemism of Australia’s swordfish-like pachycormiforms never was.

Subject of Research: Early Cretaceous palaeobiogeography and taxonomy of the pachycormiform fish Protosphyraena

Article Title: Endemism that never was? Australian swordfish-like pachycormiform in the Northern Hemisphere

Article References: Kanarkina, A., Zverkov, N. G., Khapisov, O. K., & Bolshiyanova, J. A. (2026). Endemism that never was? Australian swordfish-like pachycormiform in the Northern Hemisphere. Fossil Record, 29(1), 249-268. https://doi.org/10.3897/fr.29.191551

Image Credits: AI Generated

DOI: 10.3897/fr.29.191551

Keywords: Protosphyraena, Pachycormiformes, Albian, Cretaceous, palaeobiogeography, endemism, Dagestan, Australia, Tethys Ocean, fossil fish, never, Australian

The significance of this new collection lies not only in the number of species recovered but also in the sheer abundance of specimens available for study. Nearly 2,400 otoliths were catalogued across the six localities, and this volume of material allows paleontologists to assess relative abundance rather than simply presence or absence. The dominance of a single species, Diaphus hataii, which accounts for well over 1,700 of the counted specimens, illustrates how strongly lanternfish otoliths can dominate pelagic and neritic sediments. Such numerical dominance mirrors the ecological role of lanternfishes in modern oceans, where they form one of the most biomass-rich vertebrate groups on the planet and undertake nightly vertical migrations toward the surface to feed on plankton before returning to mesopelagic depths by day.

Otoliths themselves deserve some explanation, since they are the structures on which this entire study rests. These aragonitic concretions form in the inner ears of teleost fishes, where they serve in balance and hearing. Each fish family, and indeed many genera and species, produces otoliths with characteristic shapes, margins, and sculpturing, which means that isolated otoliths recovered from sediment can often be identified even when no skeletal material is preserved. Because otoliths are composed of calcium carbonate in the form of aragonite, they dissolve readily in acidic conditions but survive well in many marine sediments, particularly fine-grained muds deposited below depths where bottom waters remained oxygenated. This combination of taxonomic distinctiveness and preservational durability makes otoliths among the most valuable microfossils available for reconstructing ancient fish faunas, often far outperforming bones and teeth in both abundance and identifiability.

The geographic setting of the Japanese localities adds an important dimension to the findings. During the late early Miocene, the Japanese Islands were largely submerged, with broad seaways connecting the Northwest Pacific to marginal basins. Warm-water influence across western and central Honshu, noted at all six sampling sites, reflects the paleogeographic position of Japan at the margin of the subtropical to warm-temperate Northwest Pacific. The Toyama localities border what is now the Sea of Japan, a basin whose early Miocene connection to the open Pacific was different from today, and the faunal composition recovered there can therefore inform debates about when and how the Sea of Japan attained its modern circulation pattern. The presence of warm-water myctophid assemblages in these deposits is consistent with the broader picture of a Miocene climatic optimum, a globally warm interval during which tropical and subtropical marine faunas extended poleward well beyond their present ranges.

The correlation of the sampled intervals with planktonic foraminifer zone N8 and diatom zones 2B through 4A of the northern Pacific scheme demonstrates the fine temporal control available for these sections. Planktonic microfossils such as foraminifers and diatoms evolve rapidly and are widely distributed, making them the backbone of Cenozoic marine biostratigraphy. By tying the otolith assemblages to these independently established zones, the study anchors each fish fauna to a narrow window of geological time, roughly spanning the late Burdigalian and early Langhian stages. This temporal precision is what transforms a regional faunal list into a tool for correlation: if the same otolith species appear in sediments of equivalent age in New Zealand or Europe, the shared assemblage can be used to test or refine age assignments in those distant regions.

The biogeographic connections reported in the study are particularly striking. At least nine of the Japanese species are also known from coeval deposits outside Japan, most notably in New Zealand and Europe. Such a distribution implies that many lanternfish species achieved near-cosmopolitan ranges in warm and temperate oceanic waters by the early Miocene. Modern lanternfishes are indeed famous for their broad distributions, with some circumglobal species spanning entire ocean basins, aided by a pelagic lifestyle in which eggs, larvae, and adults drift with surface and subsurface currents. The fossil record now shows that this capacity for wide dispersal was already well established more than sixteen million years ago. For paleobiogeographers, this means that myctophid otoliths can serve as tracers of oceanic connectivity, revealing which marine basins were in communication and which barriers, if any, limited faunal exchange.

The taxonomic composition of the assemblage also carries ecological information. The collection includes representatives of the Myctophinae, Lampanyctinae, Diaphinae, and Gymnoscopelinae, the principal lineages within the family. The genus Diaphus dominates numerically, a pattern consistent with the modern ocean where Diaphus is among the most speciose and abundant lanternfish genera. Stenobrachius ohashii, one of the new species, is remarkably abundant at the Tsuyama locality, with more than two hundred specimens recovered, suggesting locally favorable conditions for this lineage in the neritic waters of the Katsuta Group basin. The mixture of oceanic and neritic-influenced assemblages across the localities reflects the range of depositional settings sampled, from continental slope mudstones at Niimi to shallower nearshore deposits elsewhere, and demonstrates how otolith assemblages can record gradients in water depth and proximity to the open ocean.

From a methodological standpoint, the study exemplifies the value of detailed stratigraphic measurement combined with systematic sampling. The Tsuyama section, for example, was measured across twenty-three levels, allowing the researchers to document faunal change through time within a single basin. Such fine-scale sampling is essential if otolith assemblages are ever to be used for biostratigraphic zonation in their own right, since first and last appearances of species must be documented with confidence before they can serve as index fossils. The authors explicitly frame their work as a foundation for future supraregional biostratigraphy, and the comparison of stratigraphic ranges of the observed species with data from other world regions is a first step toward building a global framework for Miocene lanternfish evolution.

The recognition of eight new species in a single regional collection also speaks to how incompletely the fossil record of mesopelagic fishes has been explored. Deep-water fishes are rarely preserved as complete skeletons, and their fossil history has traditionally been far less studied than that of shallow-water groups. Yet the abundance of lanternfish otoliths in pelagic sediments since at least the Miocene means that a rich record exists, waiting to be sampled and described. Each new regional monograph, such as this one on the Miocene of Japan, adds species that may later be recognized elsewhere, gradually knitting together a worldwide picture of mesopelagic fish evolution. The earlier review of Pliocene and Pleistocene myctophid otoliths from Japan by the same research collaboration established a younger baseline, and the present study now extends that record back into the early Miocene, opening the possibility of tracing lineages across many millions of years.

For paleoceanographers, the assemblages offer a proxy for water temperature and productivity. Lanternfishes are most diverse in warm, productive waters, and the composition of their fossil assemblages can indicate the position of oceanographic fronts and the strength of current systems. The warm-water character of the Honshu assemblages fits within the broader context of the early Miocene, when the closing of the Tethys seaway was reshaping global ocean circulation and when the Northwest Pacific supported rich neritic faunas across the flooded Japanese archipelago. Continued study of these otoliths, integrated with diatom and foraminiferal data from the same sections, promises to refine reconstructions of the paleoenvironment of the Northwest Pacific during a key interval of global climatic and tectonic change.

Subject of Research: Miocene lanternfish otoliths from Japan

Article Title: Lanternfish otoliths ( Myctophidae , Teleostei ) from the Miocene of Japan

Article References: Schwarzhans, W., Ohe, F., Tsuchiya, Y., & Ujihara, A. (2022). Lanternfish otoliths (Myctophidae, Teleostei) from the Miocene of Japan. Zitteliana, 96, 103-134. https://doi.org/10.3897/zitteliana.96.83571

Image Credits: AI Generated

DOI: 10.3897/zitteliana.96.83571

Keywords: lanternfish, otoliths, Myctophidae, Miocene, Japan, paleobiogeography, biostratigraphy, new species, mesopelagic, fossil fish, Teleostei, scientific research

The Réalmont Basin is a small, fault-bounded sedimentary depression in the Tarn department, measuring just seven kilometres from north to south and 2.5 kilometres from east to west. Like dozens of similar basins scattered across the remnants of the Variscan orogeny, it formed within the interior zones of the ancient mountain chain that assembled during the late Palaeozoic. Sediments accumulated in alluvial fans, floodplains, and shallow lakes, preserving a snapshot of continental ecosystems at the Carboniferous-Permian transition. Until now, the only hints of fossil life from this basin were mentions of plant fragments and unidentified fish scales recorded in unpublished reports from the 1970s, which later publications repeated without further detail.

That changed when prospections in 2025 and 2026 at the Cantemerle locality, where the Cantemerle Formation outcrops along a roadside, brought to light a rich collection of vertebrate remains now housed at the Muséum d’Histoire Naturelle de Toulouse. The fossils come from finely laminated black shales interbedded with sandstones, interpreted as deposits of a lacustrine environment periodically interrupted by coarse alluvial debris flows. The articulated fish skeletons are concentrated at the base of one of these shale layers, suggesting rapid burial events that entangled whole bodies before decay could scatter the bones.

Among the most striking finds is a partially preserved fin spine belonging to a hybodontiform shark of the so-called Lissodus morphotype. The spine, measuring an estimated 35 to 45 millimetres in total length, displays smooth longitudinal costae, a strong anterior keel, and a single median row of hooked denticles along its posterior face. These features are characteristic of Palaeozoic hybodontiforms traditionally assigned to the genus Lissodus, though the authors caution that a comprehensive revision of Palaeozoic material has never been undertaken. The Réalmont spine shows a unique combination of seven proximal costae and approximately twelve denticles per centimetre, differing from all comparable Palaeozoic species, and is therefore conservatively assigned to Hybodontiformes indeterminate pending additional remains.

Equally significant is a suite of acanthodid remains, including cranial fragments, scapulocoracoids, fin spines, gill rakers, branchiostegal rays, and several partial postcranial skeletons. Acanthodians, often called spiny sharks, were toothless zooplanktivores that persisted into the early Permian in European freshwater basins. The Réalmont specimens share the combination of a bent, toothless mandibular splint, an inverted Y-shaped scapulocoracoid, smooth sabre-shaped fin spines with a longitudinal groove, and small rhombic scales that define the European Stephano-Permian acanthodids Acanthodes and Westrichus. However, the absence of complete specimens and the plesiomorphic nature of most preserved characters prevent a specific identification, and the material is assigned to Acanthodidae indeterminate.

The centrepiece of the discovery, however, is an abundance of material belonging to the ray-finned fish Progyrolepis cf. heyleri. This predatory actinopterygian, which could reach 70 to 80 centimetres in length, is represented by a fragment of maxilla bearing the diagnostic vermicularly curved ridges of the genus, isolated conical teeth with ornamented ganoine collars, five postcranial skeletons showing signs of skeletal immaturity, and hundreds of isolated scales. The scales display a distinctive ornamentation of diagonally oriented ridges that divide each scale into anteroventral and posterodorsal halves, a pattern shared with the macrodont predatory fish of the late Variscan basins. The postcranial skeletons preserve details of the anal, dorsal, and caudal fins, including basal fulcral scales and grooved lepidotrichia segments, matching the anatomy described for Progyrolepis heyleri from the Bourbon-l’Archambault and Brive basins in central France.

Perhaps the most evocative specimens are four black, shiny coprolites, fossilised faeces, recovered from the same layers. Micro X-ray fluorescence analysis conducted at the Museum für Naturkunde Berlin revealed that the coprolitic matrix is composed primarily of calcium and phosphorus, consistent with calcium phosphate minerals, in sharp contrast to the aluminium, silicon, and iron of the surrounding sediment. Embedded within the matrix of one coprolite are three quadrangular scales whose ornamentation is identical to the mid-body flank scales of Progyrolepis cf. heyleri. The absence of a spiralled structure, which would be expected from a chondrichthyan producer, combined with the crushing dentition of the Lissodus-type shark, points to Progyrolepis itself as the most plausible producer. If correct, this would suggest that the Réalmont predator was not only hunting other fish but consuming members of its own kind, an early hint of cannibalism in a Palaeozoic freshwater ecosystem.

The faunal assemblage also carries important biostratigraphic weight. Progyrolepis heyleri is known only from the early Autunian of the French Massif Central, in deposits lying just above the Autunian-Stephanian C boundary. In the Buxières Formation of the Bourbon-l’Archambault Basin, the vertebrate-bearing level has been radiochronologically dated to 298.592 plus or minus 0.075 million years ago, an early Asselian age close to the Carboniferous-Permian boundary. The presence of the same fish in the Cantemerle Formation confirms the early Autunian age previously proposed on the basis of the macroflora, anchoring the Réalmont Basin firmly in the earliest Permian.

Beyond dating, the discovery reshapes our understanding of Progyrolepis itself. A critical review of the genus’s fossil record reveals that several historical attributions are invalid. The species Progyrolepis tricessimalaris from the early Permian of Texas differs fundamentally from the genus in its cranial anatomy and must be excluded. Fragmentary remains from New Mexico and Colorado lack the diagnostic characters of Progyrolepis and should be treated as indeterminate actinopterygians. Even the long-cited occurrence of Progyrolepis speciosus in the Puertollano Basin of Spain, never described or illustrated, requires verification. When these questionable records are removed, Progyrolepis emerges as a genus restricted to the Stephanian B through early Autunian of the Bohemian Massif and the French Massif Central, with P. speciosus in Bohemia and P. heyleri in France.

This restricted but still substantial distribution challenges a broader pattern. Most families of late-Variscan actinopterygians, including the amblypterids, igornichthyids, and elonichthyids, exhibit strong species-level endemism, with individual species confined to single basins or small clusters of neighbouring basins. The pronounced endemism of these small-bodied fish has been linked to their size, which implies high rates of evolution and rapid local differentiation. Progyrolepis, by contrast, spans both the French and Bohemian massifs, suggesting that its larger body size and correspondingly lower evolutionary rate allowed it to maintain wider geographic ranges even as the landscape dynamics of the Variscan range provincialised its species into separate French and Bohemian populations.

The affinities of Progyrolepis have also been clarified. Previous classifications placed it among the Palaeoniscidae, a wastebasket group, or within the Pygopteridae and Acrolepidae, but the new material and a review of skull anatomy show that these placements are untenable. Recent cladistic analyses of late Variscan actinopterygians place Progyrolepis in a clade of macrodont taxa alongside Briveichthys chantepieorum and the Elonichthyidae, sharing characters such as a large flat maxilla, two rows of marginal teeth, numerous branchiostegal rays, and identical scale ornamentation. The authors refrain from formally assigning Progyrolepis to the Elonichthyidae, noting differences in the lacrimal bone, the absence of a presupracleithrum, and the shape of the maxilla, but the possibility of a close evolutionary link between all Variscan macrodont forms is now firmly on the table.

Finally, the palaeobiogeographic implications of the Réalmont assemblage are profound. The ichthyofauna of the Cantemerle locality is identical to that of the Buxières-les-Mines locality in the Bourbon-l’Archambault Basin, demonstrating an active aquatic connection between the northern and southern basins of the French Massif Central during the early Autunian. At a larger scale, the similarity between the Réalmont fauna and that of the Bohemian basins, where Lissodus and Progyrolepis speciosus co-occur in the Stephanian C, indicates a direct dispersal corridor between the French Massif Central and the Bohemian Massif. Because none of these basins were connected by marine routes at this time, the dispersal must have occurred through continental freshwater pathways, painting a picture of interconnected lake systems threading through the Variscan highlands that allowed large predatory fish to move across hundreds of kilometres of ancient mountain terrain.

Subject of Research: Early Permian fossil fish assemblage and coprolites from the Réalmont Basin, France, and their palaeobiogeographic and taxonomic implications

Article Title: New palaeontological remains from the early Permian Réalmont Basin (Tarn, France): implications for late-Variscan palaeobiogeography and Progyrolepis taxonomy ( Actinopterygii )

Article References: Gonçalves, D., Delsahut, B., Hamann, C., & Rebillard, A. (2026). New palaeontological remains from the early Permian Réalmont Basin (Tarn, France): implications for late-Variscan palaeobiogeography and Progyrolepis taxonomy (Actinopterygii). Fossil Record, 29(2), 469-497. https://doi.org/10.3897/fr.29.197176

Image Credits: AI Generated

DOI: 10.3897/fr.29.197176

Keywords: Progyrolepis, Réalmont Basin, early Permian, Variscan Belt, palaeobiogeography, actinopterygii, hybodontiform, acanthodid, coprolites, French Massif Central, Carboniferous-Permian boundary, fossil fish

The specimen itself is modest in appearance. When collector J. L. Goedert found the concretion fragment at extreme low tide in April 2025, the fish remains were slightly etched by natural weathering and protruding from two sides of the rock. Scales and bones were closely packed around three vertebrae that were still in apparent articulation, and careful preparation revealed a single otolith, the ear stone that fishes use for balance and hearing. All of the remains are assumed to come from one individual fish, now registered as the holotype specimen UWBMVP 128914 at the University of Washington’s Burke Museum in Seattle. The species is named for Michael A. Rich of the Burke Museum, who has produced numerous research photographs for the paleontology team there, including the images of the new species.

What makes the find remarkable is where it came from. The Makah Formation, the rock unit that yielded the concretion, was deposited in a deep-marine basin-plain environment well offshore during the early Oligocene. The formation is dominated by turbidites, thick sections of structureless mudstone and siltstone, and alignments of calcareous concretions that help define the bedding. Within those concretions, researchers have found glendonites, minerals that indicate bottom water temperatures near freezing. Fossils of any kind are rare in this part of the Makah Formation, but the preserved biota includes mollusks, sea pen axes, whales, wood falls, and distinct invertebrate communities that lived at cold hydrocarbon seeps. The only fish previously mentioned from this interval was a bone fragment and some scales of an indeterminate aulopiform, protacanthopterygian or scombroid, making the new grenadier a significant addition to the deep-water record.

Preparation of the fossil required patience and precision. The specimen was etched with dilute formic acid at roughly five percent concentration, and final cleaning was done in an ultrasonic bath for fifteen minutes. Because the bones, scales and otolith had been replaced by silica, they survived the acid treatment while the surrounding carbonate dissolved away. Individual scales were photographed with a Canon EOS 5DS digital camera and a 65 mm macro lens mounted on a vertical carriage, with custom-built software controlling the camera’s movement to allow precision focusing. For some scales, up to fourteen images were stacked to produce sharp composite photographs. Comparative scales from modern grenadiers held in the ichthyological collection of the Zoological Museum Hamburg were stained with Alizarin Red to make their characters easier to see, and the images were stacked using the software Helicon Focus.

The otolith proved to be the key to identifying the fish. At 14.5 millimeters in length, it is large, with an overall oval shape and a length-to-height ratio of 1.4. Its dorsal rim is low and broadly undulating, with a depression near the middle and a rounded postdorsal high, while the ventral rim is regularly curved and deepest in front of its middle. The inner face carries a wide sulcus, the groove that houses the sensory epithelium of the inner ear, positioned supramedian and containing two large, nearly equally sized, closely spaced colliculi. The absence of a pseudocolliculum in the narrow collum, together with the otolith’s robust proportions, marks the specimen as belonging to Coryphaenoides, the second most species-rich genus of the Macrouridae after Coelorinchus. The closest living analogues include Coryphaenoides carminifer from the tropical East Pacific, C. marshalli from off southern West Africa, C. rupestris from off Norway, and C. woodmasoni from the Laccadive Sea, though the fossil differs from all of them in details such as a more pointed anterior tip and the position of the deepest point of the ventral rim.

The scales are equally distinctive. They are of the cycloid-spinoid type, circular to polygonal in shape, with distinct continuous circuli and no radii or reticulate structure. Their most striking feature is the armament of spines: robust, moderately long to long, angled at 80 to 90 degrees relative to the scale surface, and, unusually, not arranged in rows. In typical body scales from the flanks, the longest spines reach one third to one half of the scale length, and in some smaller peripheral scales, which may have come from the head region or fin bases, the spines actually exceed the scale length. The authors compared the fossil scales with material from modern species including C. rudis, C. alateralis, C. subserrulatus and C. armatus, and found that the combination of characters in C. richi differs from all macrourid scales, fossil or extant, described so far. The spines are stronger than in species such as C. asper or C. guentheri, lack the broad bases seen in C. subserrulatus and many Coelorinchus species, have a single tip rather than the tridentate tips of C. marshalli, and are more densely set than in most species of the genus.

The unordered spine pattern is perhaps the most intriguing character of all. In most macrourid taxa, scale spines are arranged in parallel, sub-parallel or radial rows, sometimes with an enlarged middle row. A similar unordered pattern does occur in the modern C. rudis, but there the spines lie relatively flat in lateral view, whereas in C. richi they point straight away from the scale plane. Whether this arrangement represents a specific adaptation or a primitive condition is difficult to determine. Morphology-based phylogenies suggest that the primitive scale pattern in Coryphaenoides already showed spines ordered in rows, which would make the fossil’s pattern a derived feature. But more recent molecular phylogenetic studies do not yet include enough species of the highly diverse grenadier assemblage to allow a reliable reconstruction of the evolution of scale patterns in the family.

The authors also use the discovery to sound a note of caution about how fossil grenadiers are classified. Multiple fossil macrourid species and genera were described in 1956 based on isolated scales from Pacific Coast rocks of the United States ranging in age from Paleocene to Pliocene, but macrourid scale characters show a high degree of convergent evolution, meaning that very similar features can appear in only distantly related taxa. Several of those older taxa, particularly at the genus level, must be considered doubtful because of the limited comparative material used. Even though the scales of C. richi are highly characteristic, the researchers recommend that fossil macrourid taxa should not be described on the basis of isolated scales alone; it was the combination of otolith and scales that allowed a confident identification here.

The broader significance of the find lies in what it says about the history of the deep sea. The Eocene-Oligocene Transition, around 34 million years ago, was a pivotal interval in which deep-ocean circulation shifted from a halothermal system to a thermohaline one. This change brought well-oxygenated but cold water into the deep ocean and triggered, or accelerated, the depth migration of certain fish groups that are now iconic inhabitants of the deep, including the Macrouridae and many Ophidiiformes, which had mostly inhabited shallow seas during the preceding warm-house period. The earliest fossil macrourids are known from middle to lower shelf environments of Paleocene Denmark and Australia, and during the Eocene warm-house their otoliths are found commonly in shallow-water deposits of Antarctica. As cooling set in during the middle to late Eocene, macrourids began venturing into bathyal realms, and depth segregation of macrourid speciation has been observed in the late Eocene and Oligocene fossil record of New Zealand.

Against that backdrop, Coryphaenoides richi from the lower Oligocene deep-water rocks of the Makah Formation confirms that the family was by then firmly established in bathyal environments of the northeast Pacific, and that one particular lineage within the genus Coryphaenoides was already evident. Earlier Oligocene records of Coryphaenoides otoliths are few and require revision, as some may represent extinct macrourid genera instead, and no records of the genus are known from Eocene strata, even though the earliest macrourids date back to the Paleocene. Today, species of Coryphaenoides are characteristic demersal fishes at bathyal and abyssal depths and rank among the deepest-living teleosts known. A fish that began diversifying as the deep ocean cooled and oxygenated now thrives in some of the most extreme habitats on Earth, and the tiny concretion from a Washington beach preserves a snapshot of that transformation in progress.

Subject of Research: A new Oligocene deep-sea grenadier fish species from Washington State illuminating the early evolution of macrourid fishes

Article Title: Coryphaenoides richi sp. nov. ( Macrouridae , Teleostei ) from the deep-marine, Oligocene Makah Formation of Washington State, U.S.A.

Article References: Schwarzhans, W. W., Moritz, T., & Goedert, J. L. (2026). Coryphaenoides richi sp. nov. (Macrouridae, Teleostei) from the deep-marine, Oligocene Makah Formation of Washington State, U.S.A.. Zitteliana, 100, 31-38. https://doi.org/10.3897/zitteliana.100.182311

Image Credits: AI Generated

DOI: 10.3897/zitteliana.100.182311

Keywords: Coryphaenoides richi, Macrouridae, grenadier fish, Oligocene, Makah Formation, deep sea, paleontology, otolith, fossil fish, Eocene-Oligocene Transition, Washington State, marine paleontology

The placoderms in question lived around 385 million years ago during the Devonian Period, often called the Age of Fishes, in the rich marine ecosystems of the famous Gogo Formation in Western Australia. This world-renowned fossil site has been the focus of decades of research, including long-running collaborations with the local Gooniyandi and Gogo community, and has yielded some of the most exquisitely preserved three-dimensional fish fossils ever discovered. It was here that these armoured predators hunted other armoured creatures on an exotic ancient reef, and it is here that the fossil evidence for their feeding strategies has been locked away in stone, waiting for modern technology to unlock it.

Dr Alice Clement, an ARC Future Fellow at the Flinders Palaeontology Lab and a co-author of the study, explains that placoderms present an extraordinary natural experiment in the early evolution of biting. Placoderms experimented with an extraordinary range of jaw shapes and biting parts during the early evolution of vertebrates, she notes, providing a rare opportunity to understand how some of the first jaws became specialised for different diets. Unlike most animals alive today, including humans, placoderms did not possess a single lower jaw bone. Instead, their jaws were built from paired bony plates supported by cartilage, with biting surfaces that ranged from broad, flat crushing plates to sharp slicing edges armed with tooth-like structures. This anatomical diversity makes them ideal subjects for investigating how jaws first became adapted to different kinds of food.

To probe that diversity, the research team employed a technique borrowed from engineering known as finite element analysis. First author Dr Rex Mitchell, of the College of Science and Engineering at Flinders University, together with colleagues, created digital three-dimensional models of the fossil jaw bones and then performed computer-based bite simulations on them. These simulations measure how well each jaw structure could withstand and support the forces generated during biting, effectively stress-testing extinct animals in silico. The team then compared the mechanical performance of each jaw with the anatomical complexity of its biting surface, looking for patterns that might connect jaw shape to diet and feeding behaviour across the eight species they examined.

Conventional wisdom in biomechanics holds that animals feeding on hard foods, such as shells and bone, generally evolve stronger jaws with broader, flatter crushing surfaces, much like the nutcracker jaws of modern hyenas or the durophagous dentitions of many rays and wrasses. That is not exactly what the analysis revealed. Rather than finding a simple, predictable relationship between jaw strength and surface shape, the researchers discovered something unexpected: both the largest and the smallest placoderms in the study possessed the strongest jaws for handling hard bites, despite using completely different biting tools. The smallest species had broad, almost featureless crushing plates, while the largest species carried highly complex, elevated dental surfaces that bore little resemblance to their diminutive relatives.

It was an interesting surprise, says PhD student and co-author Austin Fitzpatrick. Both the smallest and largest animals had evolved strong jaws, he explains, but they had solved the problem of processing harder foods in completely different ways. The key to this paradox, the researchers suggest, lies in the relationship between predator and prey body size when the prey in question is wrapped in tough exterior armour. A small placoderm confronting a small armoured prey item did not need to break it apart at all. The prey could simply be engulfed whole and then pulverised between broad, flat biting plates, much as some modern fish swallow and crush small shelled invertebrates. Strength was essential, but anatomical complexity was not.

Larger prey presented an entirely different challenge. An armoured animal too big to fit inside a predator’s mouth first had to be broken into manageable pieces before it could be eaten. That requirement demanded more elaborate dental architecture, capable of first piercing through shell or armour before crushing the remains. The largest species in the study possessed teeth arranged along a raised bony crest, forming a structure that the researchers describe as strikingly similar to the heads of medieval armour-piercing weapons such as war hammers and poleaxes. This fearsome configuration suggests the fish used its jaws to puncture the protective coverings of its prey before breaking them apart, functioning less like a nutcracker and more like a can opener followed by a hammer.

The broader significance of the finding is that hard-object feeding among Earth’s earliest jawed vertebrates was not achieved through a single evolutionary solution. Evolution, in other words, produced a diversity of jaw designs that allowed different placoderm species to exploit different prey within the same ancient reef ecosystem, a pattern ecologists call niche separation. Two species could both be powerful biters specialised for hard-shelled food, yet occupy genuinely different ecological roles depending on what they could fit in their mouths and how they had to dismantle it. This paints a picture of the Devonian reef as a complex, ecologically structured environment in which early vertebrates were already carving out specialised feeding niches hundreds of millions of years before the first tetrapods crawled onto land.

The study also reinforces the central place of placoderms in the story of human evolution. Flinders Emeritus Professor John Long, a co-author who has worked at the Western Australian fossil site for 40 years and found some of the specimens used in this study, emphasises that since 2013 placoderms have been directly linked to our own lineage as the starting point of the line leading from fishes to humans. Understanding placoderms, he argues, is now vital to revealing the origins of the human body plan. Their jaws, in particular, represent the evolutionary foundation upon which all later vertebrate mouths, from shark snouts to human faces, were ultimately built, making every new insight into how these structures functioned a contribution to a deeply personal chapter of natural history.

Technically, the study demonstrates the growing power of combining finite element analysis with comparative three-dimensional morphology to answer ecological questions that fossils alone cannot resolve. By measuring jaw strength numerically and then mapping it against surface complexity, the team could infer not only what these extinct fish ate but also how large their prey must have been relative to their own bodies, turning bite mechanics into a proxy for ancient food webs. The work, supported by the Australian Research Council through Discovery Projects funding, contributes to a growing picture of niche separation and ecological specialisation in the ancient Devonian reef. It shows that within a few tens of millions of years of jaws first appearing, vertebrates had already diversified into an impressive array of feeding specialists, from whole-swallowing crushers to armour-piercing giants, foreshadowing the extraordinary ecological breadth of jawed vertebrates that continues to this day.

Subject of Research: Feeding mechanics and jaw evolution in Devonian placoderms from the Gogo Formation, Western Australia

Article Title: Jaws tell tales: How ancient armoured fish munched prey whole

Article References: Jaws tell tales: How ancient armoured fish munched prey whole. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: placoderms, Devonian, Gogo Formation, jaw evolution, finite element analysis, hard-object feeding, palaeontology, Flinders University, vertebrate evolution, fossil fish, predator-prey relationships, ancient reefs