Megaraptorans were agile, two-legged carnivores closely related to tyrannosaurs, the lineage that includes the famous Tyrannosaurus rex. Despite that kinship, they evolved a strikingly different hunting apparatus. Rather than relying on massive jaws, megaraptorans possessed slender skulls and attacked their prey with powerfully muscled arms tipped by enormous curved claws. Some members of the group eventually grew to gigantic proportions and rose to the top of the food chain in the southern continents, but the newly described British species is among the smallest and earliest known, dating to the Early Cretaceous period roughly 120 million years ago. Its discovery in the United Kingdom places the early evolution of the group squarely on European soil.

Based on comparisons with its closest relatives, the research team estimates that Invictibellatrix amberina would have measured three to four metres in length and stood just over a metre and a half tall, roughly the height of an adult human. Lead author Dr Cassius Morrison of UCL Earth Sciences has suggested the animal likely bore feathers and that its claws may have reached lengths of around 10 to 20 centimetres. Its diet would have consisted of small dinosaurs, lizards and mammals, placing it in an ecological role comparable to that of a modern hyena: an active, capable predator and scavenger of mid-sized prey rather than the dominant carnivore of its landscape.

That ecological position is part of what makes the animal so intriguing from a human perspective. As Dr Morrison noted, although Invictibellatrix was not the apex predator of its time, a person encountering one would have faced a far more immediate danger than a T. rex. A human would represent roughly a third of the dinosaur’s body weight, making people perfectly sized prey that such an animal would very likely have pursued, whereas the much larger T. rex would have had little interest in prey so small relative to its own bulk. The comparison underscores how predator-prey dynamics in the Cretaceous differed sharply from the popular image shaped by the largest tyrannosaurs.

The identification of the new species depended on modern imaging applied to old material. The researchers subjected the fossil to computed tomography scanning, producing a three-dimensional model of the rear portion of the skull as well as a reconstruction of its internal cavity, effectively revealing the shape of the brain. Such braincase anatomy is highly informative in theropod dinosaurs, because the bones enclosing the brain carry features that vary consistently between major lineages and can therefore be used to test where a fragmentary specimen belongs on the dinosaur family tree.

The comparisons extended across a broad comparative sample of skulls and braincases from tyrannosaurs, spinosaurs, raptors and other bipedal carnivorous dinosaurs. A distinctive combination of anatomical traits emerged, including an oval opening where the spinal cord entered the brain and an hour-glass-shaped crest on the bones of the braincase. Neither feature alone would settle the question, but together they distinguished the specimen from every known species. When computer algorithms were used to analyse how the traits of the skull fit with those of other species, the results consistently placed the specimen within the megaraptoran family, confirming both its identity and its status as something previously unknown to science.

The geographic significance of the find is considerable. Megaraptorans are thought to have originated in Asia before migrating through Europe and eventually becoming apex predators across Gondwana, the southern supercontinent that comprised present-day Africa, South America and Antarctica. Until now, that hypothesis lacked a crucial piece of supporting evidence, because no megaraptoran fossils had ever been recovered from Europe. Co-author Charlie Scherer, a PhD student at UCL Earth Sciences, described the new species as the first proof that megaraptorans were present in Europe and that they reached Gondwana by that route rather than by island-hopping along more southern pathways. In effect, the Isle of Wight specimen anchors the middle leg of a dispersal story that had previously been inferred only from its endpoints.

To explore that story in more detail, the team used mathematical modelling to reconstruct how the global distribution of megaraptorans may have shifted through time. The models drew on the fossils discovered so far, the evolutionary relationships among the species, and reconstructions of ancient geography and climate. The results indicate that megaraptorans were globally widespread during the Early Cretaceous, the very interval in which Invictibellatrix lived. By the Late Cretaceous, tens of millions of years later, they had likely disappeared from Laurasia, the giant northern landmass that included modern-day Europe, while in the south they flourished as apex predators throughout Gondwana, attaining enormous sizes with claws reaching up to 35 centimetres in length.

The study did not determine why megaraptorans apparently died out in the north, but the authors point to plausible explanations that include shifts in climate or environment, or competition from other predators such as the tyrannosaurs that came to dominate northern landmasses in the Late Cretaceous. The southern record illustrates just how successful the lineage became where it survived. Maip macrothorax, recovered from rocks in what is now Argentina, is estimated to have been nine to ten metres long and to have weighed as much as an elephant, a stark contrast to the tiger-sized British pioneer described in this study.

The fossil itself carries a human history as rich as its scientific one. It was originally found at the foot of a cliff on the south-west coast of the Isle of Wight by the amateur palaeontologist Reginald Walter Tooley, and it was one of more than 1,000 specimens he discovered that were acquired by the Natural History Museum after his death. Senior author Professor Paul Barrett of the Natural History Museum emphasised that, despite more than 200 years of collecting on the island, new dinosaur species continue to emerge, and that carnivorous dinosaurs in particular have been elusive finds. Work of this kind, he noted, demonstrates the exceptional value of historical museum collections, in which many discoveries still await. The choice of name carries meaning as well: Invictibellatrix, meaning unconquered female warrior, was intended by the researchers to give hope and strength to those who are bullied, discriminated, victimised and oppressed, while amberina refers both to the amber found in the rocks where the fossil was discovered and to a female name. The research was funded by the Palaeontographical Society, the Royal Society and UKRI.

Subject of Research: Identification of a new Early Cretaceous megaraptoran theropod dinosaur species from an Isle of Wight fossil

Article Title: UK dinosaur fossil identified as new long-clawed predator

Article References: UK dinosaur fossil identified as new long-clawed predator. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Invictibellatrix amberina, megaraptoran, Isle of Wight, Early Cretaceous, theropod dinosaur, Natural History Museum, paleontology, Gondwana, Laurasia, tyrannosaurs, CT scanning, Royal Society Open Science

Living mammals are diphyodont, meaning they grow only two generations of teeth: a deciduous, or milk, set followed by a permanent set. Reptiles, by contrast, are polyphyodont, continuously replacing their teeth throughout life. Diphyodonty has long been considered pivotal to the evolution of other hallmark mammalian traits, including precise occlusion, in which upper and lower teeth fit together with exacting accuracy, and determinate growth, in which the skeleton stops growing once adult size is reached. Because teeth cannot keep being replaced if the precise fit of opposing crowns is to be maintained, the transition from polyphyodonty to diphyodonty has been viewed as a critical gatekeeper in mammalian evolution. Yet reconstructing dental replacement in fossils is notoriously difficult, because growth series that capture animals at different life stages are rarely preserved, and interpretations of Mesozoic mammal dentitions have relied largely on indirect evidence from tooth wear, crown morphology, and phylogeny.

Dongoconodon changes that picture with direct evidence. The holotype skeleton, catalogued as IMMNH-PV01700 and housed at the Inner Mongolia Museum of Natural History, preserves a well-ossified cranium, robust mandibles, and an articulated postcranial skeleton missing only the right forelimb elements. Computed tomography scanning at a voxel size of 21.95 micrometers allowed the team to peer inside the jawbones and map every tooth in three dimensions. The dental formula counts three incisors, one canine, three premolariforms, and four molariforms on each side of the upper jaw, with a slightly different arrangement below. The crucial observation lies in the right lower jaw, where unerupted replacement teeth sit inside the bone at positions that complicate any diphyodont reading.

The logic is subtle but decisive. In the right lower mandible, the second and third molariforms are fully erupted, while anterior to the erupted canine sit three unerupted teeth, including a first incisor that itself has a replacement tooth behind it. If this were a standard diphyodont dentition, those molariforms would have had to erupt fully before what would be two deciduous incisors, a pattern unknown in any living or extinct mammal. The team instead interprets the delayed unerupted incisors as second-generation teeth, which makes the replacement behind the first incisor a third generation. In other words, at some loci across all four tooth types, Dongoconodon was replacing teeth more than twice. The lower first molariform had already been shed, its complex replacement still embedded in the jaw, with a small enamel cap below it that appears to represent yet another generation.

Only one other mammal is known to have achieved anything similar: Gobiconodon borissiaki, a relative from the Early Cretaceous of Mongolia, which multiple specimens suggest had three generations of some of its molariform teeth. Together with Dongoconodon, these animals belong to a clade in which molariform replacement appears repeatedly. The prevailing view has held that ante-molar diphyodonty arose once at the base of Mammaliaformes, the broad group encompassing Late Triassic forms such as Morganucodon and all living mammals. That consensus was already strained by reports of diphyodonty in the Norian eucynodont Brasilodon, some 20 million years earlier than expected, and now by the clear polyphyodonty of these eutriconodontans. The authors suggest that the reappearance of tooth replacement in this lineage was likely tied to their carnivorous specializations, with large caniniform incisors and powerful jaws used for catching and ripping prey, a lifestyle in which continual tooth renewal would carry a clear advantage.

The skeleton also preserves a remarkable snapshot of one of the most contested transitions in mammalian evolution: the detachment of the middle ear from the lower jaw. In mammalian embryos, Meckel’s cartilage forms a rod connecting the future ear ossicles to the developing mandible; its proximal end gives rise to the malleus and incus, while the rest is progressively resorbed or incorporated into the jaw. Many Mesozoic mammals retain a groove on the inner surface of the mandible that housed an ossified version of this cartilage, implying that the ear ossicles still did double duty in both chewing and hearing. Dongoconodon preserves the ossified Meckel’s cartilage itself, along with the full bony middle ear apparatus of malleus, incus, stapes, and ectotympanic.

The shape of that cartilage is what makes the specimen so informative. Among eutriconodontans, two types of ossified Meckel’s cartilage were previously known: one with a mandibular attachment spanning nearly 60 percent of its length, as in Repenomamus, Liaoconodon, and Yanoconodon, and a second with an attachment of only about 25 percent. Dongoconodon’s cartilage is a straight, flattened spindle with a twist in the middle, its mandibular end compressed and touching the jaw only through a small facet. Combined with a third morphology seen in Corviconodon, where the Meckelian groove is entirely absent and the ossicles were fully detached, these three states form a transformation series. The team argues that this series mirrors the developmental sequence in living mammals, in which the connection breaks down from front to back, with separation occurring first between the cartilage and the mandible before the cartilage separates from the ear ossicles. Because similar long, short, and absent states appear across other mammalian lineages, including the one leading to placental mammals, the authors conclude that fully detached, hearing-dedicated ear ossicles evolved multiple times independently.

Beyond its evolutionary significance, Dongoconodon was plainly an animal of the water’s edge. Estimated at 115 to 190 grams, roughly the size of a water vole, it shows a femur with a flattened shaft and broadened distal end, and hands and feet strikingly similar to those of the platypus, broad and elongated with metacarpals and metatarsals that lengthen from the medial to the lateral side. Several finger bones bear dorsal flanges resembling those in the platypus where interdigital webbing attaches, suggesting Dongoconodon too had webbed extremities that could spread to maximize propulsive surface during the swimming stroke. A canonical variate analysis of 13 limb-bone functional indices across 124 extant mammal species placed the fossil squarely within the morphospace of semiaquatic species, with a 100 percent posterior probability for that classification.

Its tail adds a final flourish. Nineteen caudal vertebrae are preserved, with the proximal ones bearing flattened, plate-like centra and box-like transitional vertebrae that closely resemble those of the nutria, the semiaquatic South American rodent. This points to a tapered tail, dorsoventrally flattened but narrowing to a point, used mainly for steering and stabilization rather than propulsion. That combination, platypus-like webbed forefeet providing the main thrust and a nutria-like tail for maneuvering, distinguishes Dongoconodon from other semiaquatic Mesozoic mammaliforms such as Castorocauda, which paddled with a broad beaver-like tail, and Liaoconodon and Yanoconodon, whose caudal vertebrae lack flattened transverse processes.

Taken together, the fossil dismantles the tidy linear narrative in which key mammalian characters accumulated in lockstep along a single path toward the modern condition. Eutriconodontans now display a mosaic of states: Triconodon was diphyodont with precise occlusion, while Dongoconodon reverted to polyphyodonty; the Meckelian sulcus ranges from elongated forms resembling Morganucodon to fully detached ossicles like those of living mammals. Dental, occlusal, and auditory features, the evidence suggests, could evolve independently and even reverse course, producing complex combinations of ancestral and derived traits. For a lineage that branched off more than 120 million years ago, Dongoconodon platycauda offers a vivid reminder that early mammalian evolution was less a staircase than a branching experiment, with some lineages finding their own solutions to the demands of predation, hearing, and life in the water.

Subject of Research: Dental replacement, middle ear evolution, and semiaquatic adaptation in an Early Cretaceous eutriconodontan mammal

Article Title: A polyphyodont, semiaquatic eutriconodontan mammal from the Early Cretaceous of China

Article References: Bi, S., Shi, Y., Li, Z., Rahmat, S. J., Wang, J., & Wible, J. R. (2026). A polyphyodont, semiaquatic eutriconodontan mammal from the Early Cretaceous of China. Nature Communications, 17(1), Article 10032. https://doi.org/10.1038/s41467-026-77339-w

Image Credits: AI Generated

DOI: 10.1038/s41467-026-77339-w

Keywords: Dongoconodon platycauda, Eutriconodonta, polyphyodonty, diphyodonty, Meckel's cartilage, middle ear evolution, Early Cretaceous, Jiufotang Formation, semiaquatic mammals, tooth replacement, Mesozoic mammals, paleontology

At first glance, the animal hardly seems like a revolutionary. Measuring just fifty centimeters from nose to tail tip and weighing roughly two kilograms, Megacauda sungei would look modest next to any of the mammals alive now, from rhinoceroses to whales and elephants. Yet in the Mesozoic Era, spanning roughly 230 to 66 million years ago, size meant something entirely different. This was the age of the dinosaurs, and the early ancestors of mammals lived in the shadows of these giants, often weighing only a few grams. Against that backdrop, a half-meter aquatic predator was a genuine heavyweight, which is why the researchers describe it with a certain irony as a top predator of its day. Its very name, combining the Latin for large tail with an homage to Professor Sun Ge, Honorary Director of the Paleontological Museum of Liaoning, signals the animal’s most striking external feature.

That feature is also a window into its lifestyle. With its short coat and flattened tail, Megacauda sungei resembles an otter, a beaver, or a platypus, and like those modern animals it was clearly at home in the water. Three-dimensional reconstructions built from computed tomography images of the fossil suggest a swimming style that was both coordinated and efficient: the animal paddled with its front legs, propelled itself with wave-like undulations of its tail, and steered with its hind legs. According to paleontologist Professor Thomas Martin of the University of Bonn, this is the earliest evidence of an aquatic lifestyle in mammals, pushing back the timeline for when mammal relatives first committed to life in rivers and lakes. The finding adds a swimming specialist to a docodont family tree that already included tree-dwellers and burrowers comparable to moles, underscoring how experimentally diverse these early mammaliaforms were.

The teeth tell their own story of adaptation. The specialized canines of Megacauda sungei are distinctive in having three roots, an unusual anatomical arrangement, and the cusps of its teeth curved backwards. That backward curvature is a classic adaptation for gripping slippery, struggling prey, and it fits neatly with the picture of an aquatic hunter chasing fish or other slick animals through the water. Combined with the streamlined tail and paddling limbs, the dentition paints a coherent portrait of a predator fully integrated into its aquatic ecosystem, not merely an occasional visitor to the water’s edge. For an animal living in the shadow of dinosaurs, such specialization likely meant the difference between ecological success and obscurity.

But the true evolutionary revolution revealed by this fossil lies deeper than teeth or tails, hidden in the anatomy of the throat. Many animal groups lack a soft palate entirely and possess only a simple hyoid bone apparatus without any true swallowing mechanism. Crocodiles illustrate the alternative strategy vividly: to get unchewed prey down their throats, they raise their heads and use jerky movements, relying on gravity to do the work. As Professor Martin explains, this is achieved with the aid of gravity alone. Mammals, by contrast, evolved a complex hyoid structure in the pharynx that allows them to swallow against gravity. It is the reason a human being can drink upside down through a straw while continuing to breathe, an ability that seems trivial until one appreciates how few animals on Earth can manage it.

The soft palate is the keystone of this system. By separating the oral cavity from the pharynx, it permits swallowing and breathing to proceed without interference, and it keeps food and liquid from entering the nasal passages. This anatomical arrangement is a critical prerequisite for suckling, allowing newborn mammals to feed on nutrient-rich milk safely and efficiently. In the words of Professor Martin, it was this adaptation that made brain development, eventually leading to humans, possible. The soft palate and the shaping of the oral cavity and pharynx are directly linked to the evolution of mammals as a lineage. What the new fossil demonstrates is that this transformation was already underway, and apparently well advanced, in Megacauda sungei tens of millions of years before the emergence of modern mammals.

Classifying the animal required extensive comparisons with other fossils and with living species. The team, led by Professor Chang-Fu Zhou of Shandong University, Professor Zhe-Xi Luo of the University of Chicago, and Professor Thomas Martin of the University of Bonn, determined that the specimen, discovered at Xiayingzi in Inner Mongolia, belongs to the docodonts, an extinct group of early mammaliaforms that flourished primarily during the Jurassic period. Docodonts are not on the direct line to today’s placental mammals, marsupials, and monotremes, but they are close relatives whose anatomy offers a rare glimpse of the evolutionary experiments that accompanied the origin of the mammalian body plan. Within this group, Megacauda sungei stands out as the largest Jurassic mammaliaform yet known, a fact that reshapes assumptions about how big these animals could grow while dinosaurs dominated the land.

The path from discovery to publication was long and, as is so often the case in paleontology, began with chance. The Paleontological Museum of Liaoning in Shenyang acquired the specimen years ago together with other finds, and its significance only became apparent during a joint examination by the three senior researchers. Once the unique nature of the fossil was recognized, it took years of painstaking work before all examinations were complete and the new species could be securely classified, described, and documented. Martin describes the outcome as the result of a long period of teamwork, and the effort paid off handsomely: the description of the new species has unlocked countless secrets relating to the origin of mammals, from the mechanics of aquatic locomotion to the deep history of the throat anatomy that makes suckling, and ultimately large mammalian brains, possible.

Beyond its individual significance, Megacauda sungei changes the broader picture of early mammaliaform evolution. Together with other finds, it shows that docodonts occupied an astonishing range of ecological niches across the Northern Hemisphere during the Jurassic: some lived in trees, others underground like moles, and others, like the new species, in water. As Martin summarizes, this demonstrates how widespread docodonts were and that this diverse group of animals developed very different lifestyles at an incredibly early stage. A creature barely half a meter long, once dismissed as just another small fossil, thus carries an outsized message: the fundamental innovations that define mammals, from swimming bodies to swallowing throats, were assembled piecemeal and remarkably early, in the shadows of the dinosaurs, by animals small enough to hold in two hands.

Subject of Research: The anatomy and evolutionary significance of the Jurassic aquatic mammaliaform Megacauda sungei

Article Title: “Top predator” from the Jurassic measures just half a meter

Article References: “Top predator” from the Jurassic measures just half a meter. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Megacauda sungei, docodont, Jurassic, mammaliaforms, soft palate, paleontology, Inner Mongolia, aquatic adaptation, hyoid apparatus, mammalian evolution, Nature, fossil

Uintatheres emerged roughly 58 million years ago, fewer than 10 million years after the asteroid impact that ended the age of dinosaurs, and they persisted in the fossil record for around 20 million years. They were among the largest land mammals of their time, notable for their bulk, their prominent horns and their large canine teeth. Because living relatives of such animals are long extinct, paleontologists have traditionally inferred differences between the sexes from clusters of size and ornament in fossil samples. If a collection of skulls seemed to sort into a big-horned group and a small-horned group, the natural interpretation was males and females. For uintatheres, that interpretation hardened into orthodoxy: males were depicted as much larger animals bearing far more dramatic cranial features than females, a picture repeated in museum halls, popular books and scientific literature alike.

The new research began, fittingly, with a puzzle far smaller than a meter-long skull. Kevin Mulcahy, a doctoral student at the University of Kansas Biodiversity Institute and Natural History Museum, and his doctoral adviser K. Christopher Beard, senior curator at the institute, were trying to identify a single broken upper molar collected during fieldwork in Montana, a tooth they suspected might belong to the uintathere group. To solve that problem, the two traveled to the American Museum of Natural History in New York, whose storied vertebrate paleontology collections hold entire shelves of uintathere skulls, each nearly a meter long. These are famous specimens, described and redescribed in the literature for decades, and the original goal was simply to compare teeth and pin down the identity of the Montana fossil.

What Mulcahy found instead was a pattern that did not match the textbooks. As he examined the celebrated skulls to compare their teeth, he noticed an enormous amount of variation — but it did not appear to fall into two neat categories. Working quickly, he took a series of measurements of the skulls with a ruler and began exploring them statistically. The logic of the test is straightforward: if a sample of fossils truly reflects a strongly dimorphic species, measurements of traits such as skull size, horn development and canine dimensions should fit a bimodal distribution, with two peaks corresponding to average males and average females. If the species is not strongly dimorphic, the same measurements should instead follow a single, unimodal distribution. When he ran the analysis, the expected two-peak pattern was nowhere to be found.

“It wasn’t like there’s one group of specimens that look bigger than another, and then there’s another group that are smaller with smaller horns and canines,” Mulcahy said. That observation raised an uncomfortable question: were uintatheres really such good examples of sexual dimorphism after all? Was there actual evidence in the morphology of the skulls — in the distribution of the ranges of morphology — that two sexes were being sampled? To find out, Mulcahy broadened the project, gathering additional measurements from specimens held at other institutions and applying newer statistical procedures. His final dataset included about 30 skulls of Uintatherium anceps, the species at the heart of the dimorphism story.

The results were underwhelming for the traditional view. “Maybe there were some little signals of dimorphism here and there, but nothing really concrete,” Mulcahy said. Yet a skeptic could still object that the methods themselves were too weak to detect dimorphism if it existed. Fossil samples carry a fundamental handicap: no one actually knows which specimens are male and which are female. Researchers can guess, assigning the most extreme individuals to one sex and the least extreme to the other, and then test whether the groups differ — but as Mulcahy points out, that procedure is deeply circular. Of course the groups will differ if you built them by sorting extremes in the first place.

To break that circularity, Mulcahy turned the same statistical techniques on a living animal whose sex could be verified with certainty: the modern bison. Bison offered an ideal comparison. They are another very large herbivore, they occupy an ecology broadly similar to what has been proposed for uintatheres, and they carry substantial horns, making them a plausible modern analogue for testing how dimorphism signals appear in skull measurements. The contrast with the fossils was striking. In the bison sample, the dimorphism signal was clear and strong: females clustered with females and males clustered with males in an almost perfect separation. The methods, in other words, were fully capable of detecting sexual dimorphism when it genuinely exists — which made its near absence in the uintathere skulls all the more meaningful.

If the statistics were sound and the sample was adequate, then the flagship example of sexual dimorphism in the mammalian fossil record may never have deserved the title. Mulcahy suggests that the mistaken assumption has deep historical roots, reaching back to the late 19th and early 20th centuries, when so many fossil species were first described. This was the era in which evolutionary theory, sexual selection and natural selection were entering scientific discourse, and the field was dominated by male paleontologists working within a distinctly Victorian-era mindset. Within that intellectual climate, the idea that males would be bigger and more fearsome than females was less a hypothesis to be tested than an assumption to be illustrated. “When you step back and actually test that hypothesis, it doesn’t really hold up,” Mulcahy said.

The implications extend well beyond uintatheres. If a species long regarded as the classic, near-definitive case of dimorphism yields only weak and inconclusive signals under modern analysis, then other fossil species whose dimorphism was asserted on similar grounds may deserve re-examination as well. The finding also speaks to a broader debate about the evolution of size differences between the sexes across the mammalian family tree. Strong, big-male-style dimorphism was probably not ancestral at the root of the mammalian tree, Mulcahy noted; among living mammals where the pattern does appear, it has almost certainly evolved independently several times. The assumption that males are typically larger than females, he argued, reflects a long-standing bias in which animals scientists chose to study and which questions they found interesting.

That bias has been quantified in recent work on living mammals. As Mulcahy points out, a paper published just a couple of years ago showed that among modern mammal species, most either show no sexual dimorphism at all or actually feature larger females. The popular image of the animal kingdom as a place where males invariably outweigh and out-arm females, he said, is really an artifact of which creatures biologists in the past chose to look at. For paleontology, the lesson of the uintatheres is a methodological one: claims of dimorphism in fossil species need to be tested against explicit statistical expectations, ideally benchmarked against living species of known sex, rather than assumed from Victorian intuitions. A broken molar from Montana set that reassessment in motion, and the iconic horned giants of the Eocene may never look quite the same again.

Subject of Research: Sexual dimorphism in the extinct Eocene mammal Uintatherium anceps

Article Title: Study: ‘Classic example’ of sexual dimorphism in fossil record actually shows nuance between males and females

Article References: Study: ‘Classic example’ of sexual dimorphism in fossil record actually shows nuance between males and females. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: uintatheres, sexual dimorphism, paleontology, Eocene mammals, Uintatherium anceps, fossil skulls, statistical analysis, bison comparison, sexual selection, University of Kansas, PLOS One, mammalian evolution

The research, published in Current Biology, was led by Kiersten Formoso, an assistant professor in the Department of Ecology, Evolution, and Natural Resources in the Rutgers School of Environmental and Biological Sciences. Her team reconstructed the bodies of four kinds of mosasaurs from their nearly complete fossil skeletons and then applied principles of physics to estimate how quickly each animal could surge forward with a single, powerful sweep of its tail. The answer, she says, helps explain how these predators caught their meals and, in turn, how ancient ocean ecosystems functioned.

At the heart of the study is a movement the researchers call a slam-start. An animal curls its tail to one side and then forcefully sweeps it back, pushing against the water and driving its body forward. Formoso compares the initial surge to a swimmer pushing off the wall of a pool. It is the tail itself pushing off the water, she said. That single burst of acceleration could mean the difference between a successful ambush and a meal that swims away, or between life and death for a smaller animal trying to escape a larger hunter.

The scientific question began with an observation about the fossils themselves. Two major branches of the mosasaur family tree had differently proportioned tails, and Formoso wondered whether those anatomical differences affected how quickly the animals could launch an attack. Previous research on swimming reptiles had largely focused on cruising, the steady type of swimming in which an animal beats its tail repeatedly to move through the water. Burst performance, the sudden acceleration that helps a predator seize prey, had gone largely unquantified.

The nearly complete fossils provided detailed information about body size and tail shape, but one crucial ingredient was missing: muscle. To reconstruct the tail muscles that no longer exist, the researchers drew on the anatomy of living lizards, including the Komodo dragon, one of the closest things the modern world offers to a giant predatory reptile. With bodies and musculature estimated, the team modeled the physics of the slam-start for each of the four mosasaurs, calculating how quickly each could surge forward with one powerful tail stroke.

The calculations produced striking results. A particularly large Tylosaurus, one of the animals modeled, could have reached about 15 miles per hour with a single tail stroke. That estimate describes a brief burst rather than a speed the animal could maintain over distance, and the researchers caution that exact speeds remain uncertain. What matters more, they say, are the differences among the animals. Across the tested conditions, two species, Platecarpus and Tylosaurus, achieved faster lunges for their body size than Mosasaurus and Plotosaurus, with Platecarpus emerging as the fastest of the four.

The advantage came largely from a longer, more flexible section of the tail, which allowed Platecarpus and Tylosaurus to curl their tails farther before sweeping them back. In the models, how far the tail could curl had a much larger effect on the resulting speeds than any other variable the team tested. To make sure the findings were robust, the researchers ran the numbers across a range of assumptions about muscle power, tail flexibility, and resistance from the water. The pattern held up under all of them: the animals with the most curlable tails were the ones best built for a lightning first strike.

Such an advantage, the researchers said, would favor ambush hunting in shallow seas, where a predator could lie in wait and explode toward prey before it could react. Mosasaurus and especially Plotosaurus appear to have been better suited to a different strategy, pursuing prey across the open ocean. That does not mean Plotosaurus was slow, Formoso said. Its tail was built for sustained, tuna-like swimming rather than sudden bursts. In other words, the mosasaur family tree contained specialists in two very different hunting styles, much as modern predatory fish divide the water between sprinters and endurance swimmers.

The findings also agree with other independent clues to how mosasaurs lived. Studies of bite force, patterns of tooth wear, and the chemical makeup of fossils have all been used to reconstruct mosasaur diets and habitats, and the new burst-swimming results fit comfortably alongside that earlier evidence. The study additionally carries a New Jersey connection: alongside the four main reconstructions, the team modeled exceptionally large animals, including a Mosasaurus based on a fossil from New Jersey held by the New Jersey State Museum in Trenton, a reminder that the remains of these ocean giants lie beneath some surprisingly familiar ground.

To the authors’ knowledge, this is the first study to put numbers on burst swimming performance in any marine reptile from the age of dinosaurs, and the team is making its tools freely and publicly available so other researchers can apply the approach to additional extinct swimmers, including animals with no close living equivalent. For Formoso, whose broader research examines how animals with land-dwelling ancestors evolved to live in water, the work rests on a simple and powerful premise: the physical rules that govern swimming today also applied millions of years ago. Physics is physics, she said, and by applying those unchanging rules to fossil bones, scientists can watch long-extinct predators move again, one tail stroke at a time.

Subject of Research: Burst swimming performance and hunting strategies of mosasaur marine reptiles based on tail morphology

Article Title: Some of those ancient sea predators were built for surprise attacks

Article References: Some of those ancient sea predators were built for surprise attacks. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: mosasaurs, marine reptiles, burst swimming, tail morphology, ambush predation, Current Biology, Rutgers University, paleontology, Cretaceous seas, biomechanics, Tylosaurus, Plotosaurus

The discovery, published in the journal Royal Society Open Science, is the product of an international collaboration involving researchers from the United Kingdom, Sweden, Germany and Egypt, led by Dr Paul Burke of the Swedish Museum of Natural History in Stockholm. The team applied modern analytical techniques to museum specimens that had been waiting for more than a century to reveal their true identity. Their findings not only establish a new species but also reshape scientific understanding of how gavial crocodiles diversified across the ancient Mediterranean, a region that today hosts no crocodiles at all.

Gavials are among the most distinctive of all crocodilians, characterized by their exceptionally long, thin snouts, an adaptation for catching fish. Today the group is reduced to just two living species, the gharial, Gavialis gangeticus, and the so-called false gharial, Tomistoma schlegelii, both of which are restricted to freshwater environments on the Indian subcontinent and in Southeast Asia. The fossil record, however, tells a very different story. Gavials once enjoyed a near-global distribution spanning more than 100 million years, and many extinct species thrived in shallow marine environments, swimming in coastal seas far from the rivers their descendants now inhabit.

The fossils that led to the new species were recovered in the 1920s from the Mokattam Formation, a geological unit approximately 45 million years old that dates to the Middle Eocene epoch. At that time, much of what is now Egypt lay beneath a warm, shallow sea teeming with marine life. Among the specimens collected was a nearly complete skull, which early researchers assigned to the genus Tomistoma because of its superficial resemblance to the false gharial. For decades, the material sat within the existing framework of crocodylian classification, its distinctiveness hidden beneath a broad external similarity.

That changed with the application of contemporary palaeontological methods, most notably computed tomography scanning, which allows scientists to peer inside fossil skulls without damaging them. By visualizing internal anatomical structures that are invisible from the surface, and by re-examining the external morphology in detail, the research team identified several clear differences separating the Mokattam fossils from Tomistoma. These differences were sufficient to justify not only a new species but a new genus, Herugavialis, defined by a suite of cranial features documented in the new study, which the authors describe as providing new insights into gavialoid diversity in the Mediterranean region.

One feature in particular captured the researchers’ imagination. The skull of Herugavialis is relatively well preserved overall, but the tip of its snout is missing, lost either before or during preservation. Given the famous damaged nose of the Great Sphinx, carved from the same Eocene limestones of the Giza plateau, the parallel was irresistible. According to Professor Philip Mannion of University College London, who co-led the study, the team decided to name the new crocodile after the Egyptian god Heru, who was possibly the inspiration for the iconic monument itself. The species name cairensis references Cairo, the city beside which both the fossil and the Sphinx were found.

The naming choice weaves together deep time and human history in an unusual way. The Mokattam Formation limestones were quarried extensively in antiquity, supplying the building material for monuments that still define Egypt’s cultural landscape. Every block of stone removed from those quarries carried with it the possibility of fossils, the remains of creatures that swam in the Eocene sea tens of millions of years before the first human hands shaped the rock. Herugavialis cairensis thus becomes a rare example of a fossil species whose geological home and archaeological fame are physically inseparable.

Herugavialis was not the only crocodile patrolling the waters of ancient Egypt. The shallow marine environments that covered much of the region during the Eocene were also home to at least two other species of gavials, indicating a surprisingly rich crocodylian community in a single marine setting. This diversity challenges any simple picture of gavials as exclusively freshwater specialists and underscores how much ecological breadth the lineage once possessed. Multiple long-snouted crocodiles coexisting in the same coastal ecosystem suggests fine partitioning of resources, much as fish-eating predators in modern tropical waters divide habitats and prey among themselves.

The broader pattern emerging from the fossil record is one of dramatic fluctuation. As Dr Burke explains, throughout much of the last 50 million years the Mediterranean region hosted a high diversity of crocodiles, including gavials, but that diversity rose and fell over time in ways that appear to correspond to changes in global temperature and sea level. Warm periods with high sea levels expanded the shallow marine habitats that gavials favor, while cooler intervals and falling seas contracted them. The story ended decisively approximately 6 million years ago, when the drying of the Mediterranean, an event known as the Messinian salinity crisis, eliminated all crocodiles from the region, leaving it, uniquely among warm-climate seas, without any living crocodylian fauna.

The recognition of Herugavialis cairensis demonstrates the continuing value of historical museum collections and the transformative power of new analytical tools. Specimens collected nearly a century ago, described with the methods of their day and filed under familiar names, can yield entirely new species when revisited with CT scanning and modern comparative frameworks. For the researchers, the discovery is also a reminder that the stones beneath some of humanity’s most famous monuments preserve their own deep histories, written in the bones of animals like a long-snouted crocodile that, like the Sphinx it shares its rock with, has lost the tip of its nose to the ages.

Subject of Research: A new extinct gavial crocodile species from Eocene Egypt identified through CT-based cranial analysis

Article Title: New crocodile species discovered in rocks used to build the Great Sphinx

Article References: New crocodile species discovered in rocks used to build the Great Sphinx. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Herugavialis cairensis, gavial, crocodile, Great Sphinx, Mokattam Formation, Egypt, Eocene, paleontology, CT scanning, Mediterranean, Tomistoma, Royal Society Open Science

The defining feature of Noo-Noo is its mouthparts. These structures were exceptionally long and flexible, reaching nearly twice the length of the insect’s body. Among modern planthoppers, the closest living relatives of the newly described species, mouthparts are built like a simple needle: rigid, straight, and suited to piercing plant tissue to draw out fluids. Noo-Noo and its ancient kin, by contrast, carried feeding organs that could bend and extend, allowing them to reach food sources inaccessible to insects with more conventional equipment — deep inside cracks and crevices in tree bark, where sugar-rich fluids could be tapped.

The study was led by Dolev Fabrikant and Dr. Leonidas-Romanos Davranoglou of Tel Aviv University’s School of Zoology, part of the Wise Faculty of Life Sciences, the Steinhardt Museum of Natural History and the New Environmental School. The team examined fossil insects belonging to Neazoniidae, an ancient family of planthoppers, including 13 specimens preserved in Kachin amber from Myanmar. Kachin amber is one of the most important windows into Cretaceous terrestrial life, preserving organisms in extraordinary three-dimensional detail, and the Neazoniidae specimens it contains turned out to hold a surprise that only modern imaging technology could fully unpack.

Under close examination, the elongated mouthparts of the ancient insects revealed a surface densely covered with transverse folds. To determine whether these folds were merely decorative or structurally meaningful, the researchers turned to high-resolution micro-computed tomography, a technique that uses X-rays to reconstruct internal anatomy without damaging the fossil. The scans showed that the folds were integral to the structure itself rather than external ornamentation. Their likely function was to give the mouthparts flexibility while preventing them from kinking or collapsing under stress — much like a bendy drinking straw or a corrugated flexible hose, which can curve freely without pinching shut.

The fossils themselves provided further confirmation of this flexibility. In several specimens, the mouthparts were preserved in a bent position. Because amber freezes insects in place at the moment they are engulfed by resin, these bent postures represent snapshots of the animals as they were in life. The researchers therefore interpret the curled mouthparts as direct evidence that the structures were genuinely flexible while the insects were alive, not artifacts of preservation. Among the living relatives of Neazoniidae, no comparable structure is known, marking this as an ancient evolutionary solution that has since disappeared entirely.

The new species’ unusual appearance inspired its name. The epithet “Noo-Noo” was chosen after the friendly vacuum cleaner from the children’s television series Teletubbies, whose long, flexible hose bears an uncanny resemblance to the ancient insect’s feeding organ. The whimsical moniker belies the scientific weight of the find, but it also captures the essence of the discovery: an animal whose most distinctive feature looks like something engineered rather than evolved, a corrugated tube coiled within a creature smaller than a fingernail.

Why would an insect need such an elaborate feeding apparatus? Butterflies might seem an obvious comparison, since they use a flexible proboscis to drink nectar from flowers. The researchers, however, believe the resemblance is only superficial. The mouthparts of Noo-Noo pointed backward and functioned as a piercing-and-sucking system, a design that, like those of its modern relatives, is poorly suited to nectar feeding. Moreover, despite examining numerous fossils, the team found no convincing evidence of pollen accumulating on the insects’ bodies — the kind of sign that would indicate a role as pollinators. The butterfly analogy, in other words, fails on both anatomical and ecological grounds.

The explanation the researchers propose is more specialized: these insects were sap-suckers with a taste for what lies beneath the bark. Their long, flexible mouthparts could have snaked through narrow cracks in tree bark and guided the piercing organs toward deep vascular tissues, where nutrient-rich fluids flow. At the tip of the mouthpart sat another unusual feature — a structure with two grooved lobes that likely opened during feeding, helping to anchor the mouthpart against the walls of the crack. The researchers liken this mechanism to a wall plug expanding inside a drilled hole, holding the apparatus firmly in place while the insect fed.

The discovery may carry broader implications for understanding Cretaceous forest ecosystems. Long or corrugated feeding structures appeared in several unrelated insect groups during this period, raising the possibility that forests rich in thick-barked trees offered a competitive advantage to insects capable of reaching deeper tissues. The study notes that resin-producing forests of the Cretaceous were also associated with evidence of recurrent fires, and trees in fire-prone environments often develop thicker bark as protection. The researchers cautiously suggest that such conditions may have created ecological opportunities for unique feeding strategies — strategies that are almost entirely absent among planthoppers today, whose needle-like mouthparts reflect a very different set of environmental pressures.

Dr. Leonidas-Romanos Davranoglou stated: “The discovery of ‘Noo-Noo,’ a new species that lived approximately 99 million years ago, gives us an extraordinary glimpse into the insect world of the age of the dinosaurs. This is not merely an insect previously unknown to science, but an animal that developed an evolutionary solution with almost no modern equivalent: a long, flexible, and durable feeding organ that likely enabled it to reach food deep within tree bark. The fact that similar structures appeared in several insect groups during the Cretaceous period suggests that ancient forests created ecological conditions and opportunities very different from those we know today. The discovery of a new species like this is therefore not simply the addition of another name to the tree of life, but another piece of the puzzle that enables us to reconstruct what ecosystems looked like and how they functioned tens of millions of years ago.”

For paleontologists, the find underscores the value of amber as a time capsule. Soft structures such as flexible mouthparts rarely survive in conventional compression fossils, where delicate anatomy is crushed or dissolved over geological time. Amber, by contrast, entombs specimens in three dimensions, preserving fine surface detail and even internal architecture that can be visualized with micro-CT scanning. Without such preservation, a feeding apparatus as unusual as Noo-Noo’s might never have been recognized, and the evolutionary experiment it represents would have vanished from the record altogether.

The description of Cretodorus noonoo adds a new branch to the tree of life and, just as importantly, a new data point in the history of ecological specialization. It shows that during the age of the dinosaurs, insects were experimenting with feeding strategies that have since been abandoned, shaped by forests whose structure and fire regimes differed markedly from those of the modern world. Each such discovery refines the picture of how Cretaceous ecosystems functioned — and reminds us that evolution’s portfolio has always included designs that today seem almost alien.

Subject of Research: A new Cretaceous planthopper species with flexible, corrugated mouthparts preserved in Kachin amber

Article Title: Rare discovery reveals a new species from the dinosaur age

Article References: Rare discovery reveals a new species from the dinosaur age. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Cretodorus noonoo, amber fossil, planthoppers, Neazoniidae, Kachin amber, Cretaceous period, micro-computed tomography, insect mouthparts, Tel Aviv University, paleontology, tree bark feeding, Myanmar amber

The fossil evidence itself is not in doubt. Ratite eggshells have been recovered from Lanzarote since the 1960s and 1970s, when palaeontologists first described fossil ostrich eggs from the island’s Miocene and Pliocene deposits, and subsequent work has confirmed the presence of a terrestrial fauna in Lower Pliocene sites. What is missing is any associated skeletal material, which means the precise identity, size and anatomy of the Lanzarote birds remain inferred largely from their eggs. Oxygen isotope analyses of the eggshell calcite, published by some of the same authors in earlier work, have helped reconstruct the body water and environmental conditions of the laying females, but the fundamental question of arrival has stood unanswered. The new study does not claim to have found the smoking gun. Instead, it asks a deceptively simple question: was the journey even physically and biologically possible?

The mechanism the authors evaluate is oceanic rafting, the passive transport of terrestrial animals on masses of floating vegetation swept out to sea by rivers and storms. Rafting has long been invoked to explain the distribution of land animals on oceanic islands, from lizards and small mammals to, more controversially, larger vertebrates. Charles Darwin himself mused about floating islands carrying seeds and animals across oceans, and modern biogeographers have documented natural rafts of tangled roots, logs and plant debris drifting far from coastlines. What has made rafting unattractive for very large animals is buoyancy: a floating mat of vegetation must be enormous and structurally coherent to bear the weight of a 100-kilogram bird without disintegrating or submerging.

Lécuyer and his colleagues argue that the early Pliocene offered unusually favourable conditions for building such rafts. Geological and palaeoclimatic evidence indicates that northwestern Africa during this interval was warmer and wetter than it is today. Palaeoclimate reconstructions, including work on Pliocene monsoon dynamics and a documented North African humid period preceding mid-Pliocene glaciation, point to enhanced fluvial activity across the region. More rain means more powerful rivers, and more powerful rivers mean the mobilization of large volumes of plant debris, uprooted trees, and accumulated vegetation along drainage networks. Under such conditions, substantial floating mats of vegetation could plausibly have been launched into the Atlantic, where the Canary Current and the trade winds provide a natural conveyor toward the archipelago.

To test whether such a raft could actually carry a giant bird, the researchers turned to hydrostatics. Their calculations, based on the buoyancy of natural vegetation masses of realistic dimensions, indicate that rafts of plausible size could support an adult bird of approximately 100 kilograms without sinking. The analysis draws on comparative data from living ostriches, whose body masses, feeding requirements, water needs and physiology are well documented from field studies in the Namib and from captive populations. Ostriches are remarkably drought-tolerant animals, able to meet much of their water demand through food and metabolic processes, and their feather structure provides insulation against both heat and moisture. These physiological traits matter enormously for a castaway bird, because the limiting factor on a raft is not only buoyancy but the animal’s ability to survive days of exposure, dehydration and stress without access to fresh water or solid footing.

The second half of the study is probabilistic. Rather than asserting that a single voyage succeeded, the authors modelled survival as a function of transport duration, using survival-analysis frameworks of the kind developed for failure-time data in statistics. Their simulations show a pattern that is intuitive but has rarely been quantified for animals of this size: survival probability decreases steadily as the crossing lengthens, and adult individuals fare considerably better than eggs under the modelled conditions. An egg adrift on a wet, thermally fluctuating raft faces challenges that an adult does not. Eggs require carefully regulated temperature and humidity for the embryo inside to develop, and prolonged exposure to seawater spray, solar heating and nighttime cooling would push the egg’s microclimate far outside viable bounds. An adult bird, by contrast, can regulate its own posture, shelter behind raft vegetation, and tolerate water stress for extended periods.

To handle the many uncertainties inherent in reconstructing a voyage that happened, if it happened, nearly five million years ago, the team employed Bayesian analyses. This statistical approach allows the researchers to explore the full space of parameter combinations, raft size, drift speed, bird mass, dehydration tolerance, and transport duration among them, and to identify which combinations are compatible with a successful crossing. Rather than producing a single yes-or-no verdict, the Bayesian framework yields a landscape of plausibility, showing how the probability of success responds to changes in each assumption. The result is a nuanced conclusion: rare passive transport of adult giant palaeognathous birds across the Lanzarote Passage is compatible with the geological, physiological and oceanographic constraints considered, even though many individual voyages would have ended in failure.

The authors are careful about what their results do and do not demonstrate. The study does not prove that rafting occurred, and it explicitly frames its findings as showing compatibility rather than confirmation. No skeletal remains of the birds have been found, no raft has been observed in the fossil record, and the exact timing of the colonization relative to the deposition of the egg-bearing sediments remains a matter of stratigraphic inference. What the paper provides is a quantitative demolition of the strongest objection to rafting, namely that a giant flightless bird could not possibly survive such a journey. By showing that the physics of buoyancy and the biology of ostrich-like physiology do not rule the scenario out, the researchers shift the burden of proof. Rare events, after all, only need to happen once in millions of years to leave a permanent mark on an island’s fauna.

The implications reach well beyond Lanzarote. Island biogeographers have long debated the relative roles of dispersal over water versus ancient land connections, and the Canary Islands have served as a natural laboratory for this debate. Giant lizards of the genus Gallotia colonized the archipelago, genetic studies of the extinct giant rat of Tenerife point to recent divergence from mainland relatives, and the strange terrestrial fauna of the Lower Pliocene sites has puzzled researchers for decades. If a 100-kilogram flightless bird could plausibly make the crossing, then the rafting hypothesis becomes harder to dismiss for almost any terrestrial vertebrate. The study also highlights how climate shapes dispersal: the warm, wet early Pliocene may have opened a transient corridor of opportunity, with enhanced river discharge launching rafts that a drier climate would never produce. Colonization, in this view, is not a constant process but a window that opens and closes with the planet’s climate rhythms.

For now, the giant birds of Lanzarote remain shadows known mainly from their eggs, their bones still waiting in Pliocene rock. But the new modelling transforms them from biogeographical impossibilities into plausible castaways, birds that may have clung to a drifting tangle of African vegetation and ridden the Canary Current to a young volcanic shore. The Python code behind the survival models has been released as supplementary material, inviting other researchers to probe the parameter space further. Whether future fieldwork on Lanzarote recovers the skeletal evidence that would settle the question remains to be seen. What is already clear is that the ocean barrier that seems so absolute to us was, under the right climatic conditions, a barrier with cracks, and evolution has repeatedly found its way through them.

Subject of Research: Oceanic rafting dispersal of giant flightless palaeognathous birds to Lanzarote in the early Pliocene

Article Title: Evaluating the plausibility of oceanic rafting by giant palaeognathous birds to Lanzarote during the early Pliocene

Article References: Lécuyer, C., Buffetaut, E., & Marco, A. S. (2026). Evaluating the plausibility of oceanic rafting by giant palaeognathous birds to Lanzarote during the early Pliocene. The Science of Nature, 113(6), Article 124. https://doi.org/10.1007/s00114-026-02172-6

Image Credits: AI Generated

DOI: 10.1007/s00114-026-02172-6

Keywords: palaeognathous birds, Lanzarote, Canary Islands, Pliocene, oceanic rafting, island biogeography, paleontology, ostrich, survival probability, Bayesian analysis, hydrostatics, dispersal

The fossil material was unearthed at the La Tejería site in El Castellar, in the province of Teruel, an region that has become one of Europe’s most productive windows into Mesozoic life. Over the course of careful excavation, the team recovered fourteen exceptionally preserved caudal vertebrae, the bones of the dinosaur’s tail, along with several chevron bones, the small paired elements that hang beneath the tail vertebrae and help protect blood vessels and support musculature. Although skull material and limb bones were not part of the recovered assemblage, the quality and diagnostic character of the tail bones proved sufficient for the researchers to make a confident identification at the genus level, something rarely achievable with fragmentary sauropod remains.

Sergio Sánchez Fenollosa, a PhD student in biodiversity and evolutionary biology at Fundación Dinópolis and lead author of the study, described the slow accumulation of evidence that led the team to their conclusion. From the earliest stages of the osteological study, he explained, the researchers noticed strong similarities between the Spanish bones and several diplodocine sauropods. As the anatomical work progressed, they began to identify a combination of features characteristic of Diplodocus species, and subsequent evolutionary analyses repeatedly pointed in the same direction. With each new result, he said, the picture became clearer: the team was looking at a Diplodocus. He added that the outcome of the dig represents some of the strongest palaeontological evidence yet found for episodes of dispersal and faunal exchange between North America and Europe across the proto-Atlantic Ocean during the Late Jurassic, and that the discovery allows a better understanding of Iberian Mesozoic ecosystems and the diversity of sauropod dinosaurs that inhabited the European Jurassic.

The identification rested on a suite of distinctive anatomical features preserved in the vertebrae and chevrons. The tail bones display large pneumatic cavities, air-filled spaces that lightened the skeleton in these colossal animals, a hallmark of many sauropod lineages but expressed in a particularly characteristic form in Diplodocus. The underside of the tail vertebrae bears deep longitudinal grooves, and the chevron bones are distinctly forked, with unique medial fossae, depressions on their inner surfaces, that match the condition seen in North American Diplodocus material. The vertebral centra, the main cylindrical bodies of the vertebrae, are elongated and lack the lateral ridges found in many related diplodocids. Taken together, this combination of traits distinguished the Spanish specimen from other European diplodocids and aligned it with the Diplodocus lineage.

To test the anatomical assessment rigorously, the research team combined traditional comparative anatomy with advanced phylogenetic analyses, employing both maximum parsimony and Bayesian inference methods. These computational approaches evaluate how anatomical characters are distributed across known taxa to reconstruct evolutionary relationships. In both analytical frameworks, the Spanish specimen was confidently placed within the genus Diplodocus, and more specifically as a close relative of Diplodocus hallorum, one of the largest and longest species within the genus. The convergence of anatomical and statistical evidence is what gives the identification its strength, since isolated tail vertebrae can be notoriously difficult to assign to a precise genus among the many similar diplodocid sauropods known from the Late Jurassic.

The Spanish Diplodocus dates to approximately 150 million years ago, near the end of the Jurassic Period, a time that corresponds closely with the age of the Morrison Formation faunas in North America. Its presence in Europe provides compelling evidence that dinosaurs could migrate between the two landmasses during the Late Jurassic. The most likely mechanism, according to the researchers, involved temporary land bridges that emerged as the proto-North Atlantic Ocean underwent regressive phases, periods in which sea levels fell and exposed connections between now-separated continental areas. Such episodic corridors would have allowed herds of giant herbivores, and presumably the predators and smaller animals that followed them, to move between North America and Europe, explaining how a genus once thought to be endemic to the American West could appear on the Iberian Peninsula.

Co-author Dr Alberto Cobos, managing director of Fundación Dinópolis, emphasized the sheer scale of the animal. The Diplodocus from El Castellar was approximately 25 meters long, comparable in size to its North American relatives, making it another of the giant sauropods of the Spanish Jurassic. He noted that it joins other enormous sauropod dinosaurs from Teruel with very different characteristics from those of diplodocids, such as Turiasaurus and Losillasaurus, among others. The fossils of all these dinosaurs, including those of the new Diplodocus specimen, he said, make Teruel a reference place for understanding this great diversity. The coexistence of a diplodocid giant alongside turiasaurian sauropods of entirely different build suggests that Late Jurassic Iberian ecosystems supported multiple niches for gigantic herbivores, perhaps with the different lineages specializing in different vegetation or feeding heights.

The broader fossil record of the region reinforces that picture of ecological richness. The area where the specimen was found has yielded numerous dinosaur fossils representing sauropods, theropods, stegosaurs, and ornithopods, indicating that these ancient coastal environments supported complex and diverse ecosystems. During the Late Jurassic, eastern Iberia lay along the margins of the expanding Atlantic, with shallow seas, coastal plains, and floodplains that periodically preserved the remains of the animals that roamed them. The addition of Diplodocus to this faunal list strengthens the resemblance between Iberian and North American Late Jurassic assemblages, supporting the idea of a broadly shared dinosaur fauna across the two regions rather than isolated provincial communities.

Diplodocus itself occupies a special place in the history of palaeontology and popular culture. First discovered in the United States in 1878, the genus is famous for its enormous length of up to 25 meters, its long whip-like tail, and its relatively small head perched at the end of a gracefully curved neck. Throughout the early twentieth century, casts of Diplodocus skeletons were displayed in leading natural history museums around the world, making the animal a symbol of global palaeontology and a beloved icon of prehistoric life. Its frequent appearances in exhibitions, books, and audiovisual productions about dinosaurs have made it one of the best-known of all the so-called terrible lizards among the general public, which is precisely why the confirmation of its presence in Europe carries such resonance both scientifically and culturally.

The fossils themselves are now on display for future research and public education in the dinosaur hall of the Museo Aragonés de Paleontología at Dinópolis in Teruel, a city in eastern Spain situated roughly between Madrid and Valencia. There, visitors can see the tangible evidence of an animal that lived 150 million years ago on a planet whose geography differed profoundly from today’s, when the Atlantic was still young and narrow and continents remained within reach of wandering giants. For palaeontologists, the specimen opens new questions about how many other supposedly North American dinosaur lineages may await discovery in European rocks, and about the frequency and duration of the dispersal events that connected the faunas of two continents. For the moment, the tail bones from La Tejería stand as the first physical proof that Diplodocus, the archetypal giant of the American Jurassic, also called Europe home.

Subject of Research: First discovery of the sauropod dinosaur genus Diplodocus outside North America, from Late Jurassic deposits in Teruel, Spain

Article Title: First ever find of a Diplodocus outside of North America

Article References: First ever find of a Diplodocus outside of North America. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Diplodocus, sauropod, Late Jurassic, Teruel, Spain, paleontology, Morrison Formation, faunal dispersal, proto-Atlantic, vertebrate paleontology, dinosaurs, Iberia

The fossil, described in a study now in press at Nature’s Scientific Reports, provides the first and oldest record of a capybara in coastal Chile. But its significance extends far beyond adding a rodent to the region’s faunal inventory. If a semiaquatic giant rodent was thriving in the Atacama during the late Miocene, the desert cannot have been the unbroken hyperarid expanse that geologists have long imagined. The finding directly challenges the long-standing characterization of the Atacama as one of the oldest continuously dry regions on the planet, a status it has held in textbooks and review papers for decades. For the research team, led by doctoral student Priscilla Martinez of the University of Arizona Department of Geosciences, the implications were immediately clear and deeply unsettling to conventional wisdom.

The tooth itself emerged from a layer of sediments deposited in a shallow marine environment between roughly 10 and 7 million years ago. The site, known as El Morro, belongs to the fossil-rich Bahía Inglesa Formation, a rock unit that also contains Cerro Ballena, or Whale Hill, famously recognized as the world’s largest concentration of whale fossils. Marine deposits full of whales are one thing; a capybara tooth in the same beds is quite another. Finding a capybara tooth in a marine deposit in what today is one of the driest regions on Earth is, as Martinez put it, just freakish. The oddity of the association underscores how radically the local environment has changed since the late Miocene, when the same coastal setting that entombed whales also supported a large freshwater-dependent mammal.

Capybaras, the largest living rodents, and their close cousins the guinea pigs are native to South America. Today, capybaras thrive east of the Andes in low-elevation wetlands, with their core range roughly tracing the Amazon River basin. Their semiaquatic lifestyle tightly binds them to persistent surface water, wetland vegetation, and the ability to move along riparian corridors beside creeks and rivers. Co-author Barbara Carrapa, a professor of geosciences at the University of Arizona and Martinez’s doctoral advisor, emphasized that there is no other evidence of capybaras in that part of coastal Chile. They are not supposed to be there, she said, which immediately raised two questions for the team: why were they there, and where did they come from?

Geography makes those questions especially thorny. Geologists estimate that long before capybaras appeared in the region roughly 9 million years ago, the Andean mountain chain had already risen into a formidable barrier, in places jutting up to 18,000 feet. That towering wall effectively separates the Atacama Desert from the eastern lowlands that stretch across parts of Venezuela and Colombia down to northeastern Argentina and Uruguay, where the animals live today. Climate compounds the problem. As Martinez noted, the plateau lands of the Central Andes are not only very tall but also extremely arid. If capybaras originated east of the Andes in the foreland region, it is hard to imagine how these short-legged rodents could possibly have crossed such an inhospitable, high-altitude barrier on foot.

The most likely answer, the researchers conclude, is that they did not cross it at all. Instead, the team proposes a dispersal scenario in which capybaras expanded out of their original range by taking advantage of low-elevation wetlands that connected coastal areas in a counterclockwise arc around the northern portion of South America. From today’s Venezuela into Colombia, Ecuador, and Peru, and finally into northern Chile, the animals could have moved along a chain of verdant, water-rich habitats without ever confronting the high Andes. The scenario implies that a continuous or near-continuous corridor of wetland ecosystems hugged the Pacific coast during the late Miocene, a picture starkly at odds with the notion of an ancient, unbroken desert.

Crucially, the capybara tooth is not an isolated anomaly. Co-author Mark Clementz, a paleobiology expert and head of the Department of Geology and Geophysics at the University of Wyoming, pointed out that the same deposits contain multiple lines of evidence indicative of the kind of really wet conditions typically associated with capybaras today. Alongside the rodent remains, the sediments yielded fossils of freshwater fishes and gavials, the fish-eating freshwater crocodilians that require rivers or permanent water bodies to survive. The presence of crocodiles and freshwater fish in the same beds that preserved the capybara paints a coherent ecological picture of rivers, marshes, and wooded waterways rather than barren sand.

Botanical evidence reinforces that reconstruction. The team also unearthed phytoliths, microscopically small accumulations of silica that form inside plant cells and tissues as plants absorb dissolved silica from groundwater through their roots. Because different plant lineages produce characteristically shaped phytoliths, specialists such as co-author Caroline Strömberg, a professor at the University of Washington, can analyze these durable structures to determine what kinds of vegetation once grew at a site. In this case, the phytolith record pointed to palms and other flowering plants, including dicots, none of which would be expected in the Atacama Desert of today. Martinez offered a vivid comparison: think of sunny Southern California full of palm trees. She cautioned that researchers are not sure whether the palms bloomed extensively there, but they were definitely present, a detail that alone rewrites assumptions about the region’s past.

Together, the mammal, reptile, fish, and plant fossils support the idea that there was enough of an ecological community to sustain capybara populations over the long term, as Clementz observed. No other remains of capybaras this old have been found in Chile to date, which makes the single tooth, preserved within a three-foot-thick bed in the middle of a desert, something of a miracle of survival, according to Martinez. The assembly of strange creatures in an unlikely place did not go unnoticed by the local population. Many residents dug for fossils and sold them to collectors, and many of the fossils originally discovered at the location are now lost to science. Fortunately, certain merchants were interested in understanding the specimens better and donated them to local scientists, creating an unusual and invaluable partnership between fossil traders and researchers.

One of the beneficiaries of that collaboration was Carolina Gutstein, the study’s first author, who heads paleontology at the Chilean mining company Fosfatos de Caldera and is a professor at the Universidad Santo Tomás in Santiago. Gutstein has a long history of working with local fossil experts in the area, and those relationships proved essential in tracing and interpreting the material. Clementz added that the findings demonstrate the value of challenging assumptions, in this case the assumption that the Atacama has been an ancient desert for millions upon millions of years. No one really argued with that paradigm, he noted, even in the face of other fossil finds suggesting that conditions were once different. Finding a capybara, an animal that by any measure is not a desert creature, at that location is going to force a serious rethinking of the Atacama’s history.

The implications reach well beyond capybaras and one South American desert. Deserts are extremely sensitive to changes in climate, including year-to-year shifts in monsoon intensity, and understanding how they formed and transformed in the deep past offers a natural experiment that no laboratory can replicate. As Martinez explained, the better scientists understand deserts, the better they can predict how these environments will fare over the long term. And if researchers can reconstruct past climate changes that had nothing to do with humans, they gain a baseline against which to measure how climate may evolve in a world where human influence is now part of the equation. A single fossilized tooth, plucked from a whale-strewn marine bed in the driest place on Earth, has thus opened a window onto a greener, wetter Atacama and a reminder that even the most confident scientific paradigms can be overturned by one small, improbable piece of evidence.

Subject of Research: Late Miocene capybara fossil evidence for a wetter ancient Atacama Desert and transcontinental rodent dispersal

Article Title: Capybaras in the desert? Fossil casts doubt on Atacama as world's oldest continuously dry region

Article References: Capybaras in the desert? Fossil casts doubt on Atacama as world's oldest continuously dry region. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: capybara, Atacama Desert, paleontology, Miocene, Chile, fossil tooth, wetlands, Andes, phytoliths, climate history, Scientific Reports, dispersal