Biology

Kostensuchus atrox, a peirosaurid crocodyliform from Patagonia

By ScientifiCult 27 August 2025

Kostensuchus atrox: a crocodile-relative “hypercarnivore” from prehistoric Patagonia was 11.5ft long and weighed 250kg

Kostensuchus atrox was a top predator which lived just before the extinction of the dinosaurs, and likely chomped on them

Kostensuchus atrox – Mounted skeleton (reconstructed 3D print and painted). José Brusco, CC-BY 4.0

A newly-discovered species of a large, crocodile-relative predator has been described via a remarkably well-preserved fossil from Argentina, according to a study published August 27, 2025, in the open-access journal PLOS One by Fernando Novas from Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Argentina, and colleagues.

The Chorrillo Formation formed around 70 million years ago, during the Maastrichtian age at the very end of the Cretaceous period. At this time, southern Patagonia was a warm, seasonally humid landscape of freshwater floodplains, home to creatures like dinosaurs, turtles, frogs, and various mammals.

The new fossil unearthed in this formation is largely intact, including a skull and jaws with visible details, as well as multiple bones from the body. This crocodile-like apex predator may have reached around 3.5 meters (11.5 feet) long and weighed around 250 kilograms (551 pounds), with a wide, powerful jaw and big teeth capable of devouring large prey — likely including medium-sized dinosaurs. The researchers named the species Kostensuchus atrox, referring to the Patagonian wind known in the Tehuelche native language as the Kosten and the Egyptian crocodile-headed god known as Souchos, with atrox meaning “fierce” or “harsh”.

Kostensuchus atrox – skull already prepared, freed from the rock. José Brusco, CC-BY 4.0

K. atrox itself is not a dinosaur, but rather a peirosaurid crocodyliform, an extinct group of reptiles related to modern crocodiles and alligators. This species is the second-largest predator known to scientists from the Maastrichtian Chorrillo Formation, and the researchers believe it was likely one of the top predators in the region. K. atrox is also the first crocodyliform fossil found in the Chorrillo Formation, and one of the most intact peirosaurid crocodyliforms ever found, giving scientists unique new insight into these prehistoric animals and their ecosystem.

Kostensuchus atrox – life restauration, 3 meters long. Art by Gabriel Diaz Yanten. Gabriel Diaz Yanten, CC-BY 4.0

Author countries: Argentina, Portugal, Japan.

Funding: DP 9282-R-22 National Geographic Society https://www.nationalgeographic.org/society/ The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ISC Faperj E-26/200.998/2024 Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro https://www.faperj.br/ The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. ISC CNPq 303596/2016-3 Conselho Nacional de Desenvolvimento Científico e Tecnológico https://www.gov.br/cnpq/pt-br The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Bibliographic information:

Novas FE, Pol D, Agnolín FL, Carvalho IdS, Manabe M, Tsuihiji T, et al., A new large hypercarnivorous crocodyliform from the Maastrichtian of Southern Patagonia, Argentina, PLoS One (2025) 20(8): e0328561, DOI: https://doi.org/10.1371/journal.pone.0328561

Press release from PLoS ONE.

Keep Reading

Biology

Nipponopterus mifunensis, a Pterosaur from Japan, sheds light on ancient flying reptiles

By ScientifiCult 10 June 2025

First named Pterosaur from Japan sheds light on ancient flying reptiles – Newly identified Nipponopterus mifunensis highlights international collaboration and Japan’s rich prehistoric heritage

A team of researchers from Japan, China, and Brazil has announced the discovery of a new species of pterosaur from the Late Cretaceous of Japan, marking the first time a pterosaur has been named based on body fossils found in the country.

The species, Nipponopterus mifunensis, was identified from a partial neck vertebra originally discovered in the 1990s in the Mifune Group geological formation in Kumamoto Prefecture, located on Japan’s southern island of Kyushu. After a detailed reassessment using advanced CT scanning provided by Kumamoto University and subsequent phylogenetic analysis, the research team concluded that the specimen represents a new genus and species within the Azhdarchidae family—a group known for containing some of the largest flying animals that ever lived. The fossil is now on public display at the Mifune Dinosaur Museum in Kumamoto Prefecture, offering visitors a rare glimpse into Japan’s ancient skies.

“This is a major step forward for Japanese paleontology,” said Dr. Naoki Ikegami from the Mifune Dinosaur Museum, “Until now, no pterosaur had been formally named from skeletal remains found in Japan. This discovery provides crucial new insight into the diversity and evolution of pterosaurs in East Asia.”

Interestingly, Nipponopterus may have had a wingspan approaching 3 to 3.5 meters and lived during the Turonian–Coniacian stages of the Late Cretaceous, making it one of the earliest known members of its lineage.

The newly identified sixth cervical vertebra (neck bone) of Nipponopterus mifunensis reveals a set of striking features not seen in any previously known species. Most notably, it has a prominent, elevated dorsal keel that runs along the back of the bone—extending not just over the epipophysis but across the entire postexapophyseal peduncle. Additional distinctive traits include a long groove running along the underside (ventral sulcus), a subtriangular-shaped condyle, and unusually positioned postexapophyses that project outward to the sides. These characteristics set Nipponopterus mifunensis apart from all other known azhdarchid pterosaurs. Phylogenetic analysis places it within the Quetzalcoatlinae subfamily, identifying it as a close relative of both the mysterious “Burkhant azhdarchid” from Mongolia and the giant Quetzalcoatlus of North America.

Published in the peer-reviewed journal Cretaceous Research, the study was the result of an international collaboration involving researchers from Shihezi University in China, the Zoology Museum at the University of São Paulo in Brazil, and a team in Japan from the Mifune Dinosaur Museum, Kumamoto University, and Hokkaido University. Researchers worked closely together, combining expertise in fossil analysis, imaging technology, analytical modeling and evolutionary studies.

“It’s a beautiful example of how science transcends borders,”

noted Professor Toshifumi Mukunoki from the Faculty of Advanced Science and Technology, Kumamoto University.

Nipponopterus mifunensis, a newly identified pterosaur known from a single neck vertebra, once soared through the ancient skies of what is now Japan. Picture Credits: Zhao Chuang

Bibliographic information:

Xuanyu Zhou, Naoki Ikegami, Rodrigo V. Pêgas, Toru Yoshinaga, Takahiro Sato, Toshifumi Mukunoki, Jun Otani, Yoshitsugu Kobayashi, Reassessment of an azhdarchid pterosaur specimen from the Mifune Group, Upper Cretaceous of Japan, Cretaceous Research Volume 167, 2025, 106046, ISSN 0195-6671, DOI: https://doi.org/10.1016/j.cretres.2024.106046

Press release from Kumamoto University.

Keep Reading

Biology

Iani smithi from Utah lived at a time of major transition

By ScientifiCult 9 June 2023

New dinosaur species from Utah lived at a time of major transition: Iani smithi provides insights into how dinosaurs weather mid-Cretaceous ecological change.

Iani smithi from Utah lived at a time of major transition — Location of holotype locality for Iani smithi. (A) Global map showing location of Mussentuchit Member outcrop in central Utah, western North America, and a stratigraphic section at the quarry with dated ash horizons; and (B) graphical representation of preserved skeletal elements of the holotype specimen. Preserved elements are colored on the left facing skeletal whether they derive from the right or left side of the body. Exact positions of chevrons and ribs unknown due to poor preservation. Credits: Zanno et al., 2023, PLoS ONE, CC-BY 4.0

A new species of dinosaur from Utah sheds light on major North American ecological changes around 100 million years ago, according to a study published June 7, 2023 in the open-access journal PLoS ONE by Lindsay Zanno of the North Carolina Museum of Natural Sciences and colleagues.

The boundary between the Early and Late Cretaceous Period saw major reassembly of global ecosystems associated with a peak in global temperatures. In the fossil record of western North America, this ecological shift has been well-documented for marine habitats, but less study has been done regarding terrestrial life. In this study, Zanno and colleagues identify a new dinosaur from the early Late Cretaceous Cedar Mountain Formation of Utah.

The new dinosaur, named Iani smithi, lived around 100 million years ago and is known from a single fossil specimen including a well-preserved skull and parts of the spine and limbs. The name derives from Ianus, a Roman deity who presided over transitions, referencing the changing world of the mid-Cretaceous.

Iani is a member of an early branch of the ornithopod dinosaurs, a group of mostly bipedal herbivores that also includes famous examples like Iguanodon and Tenontosaurus. Iani is the first early-diverging ornithopod known from the Late Cretaceous of North America.

This discovery, along with other recent reports from the same geologic formation, indicates that several major groups of dinosaurs survived into the early Late Cretaceous despite the ecological changes of the time, but exactly what these survivors were doing and how long they lasted is still unclear. Since Iani and its closest cousins are typically found in ancient coastal habitats along the shores of the now-vanished Western Interior Seaway, the authors suggest that more investigation into coastal deposits of similar age might yield further evidence to address these lingering questions.

The authors add: “Early ornithopods were once a common part of North American ecosystems, but we did not know they survived into the Late Cretaceous. The discovery of Iani helps us link their extinction on the continent with a major interval of global warming, one with striking similarities to our current climate crisis.”

Bibliographic information:

Zanno LE, Gates TA, Avrahami HM, Tucker RT, Makovicky PJ (2023) An early-diverging iguanodontian (Dinosauria: Rhabdodontomorpha) from the Late Cretaceous of North America, PLoS ONE 18(6): e0286042. https://doi.org/10.1371/journal.pone.0286042

Press release from the Public Library of Science.

Keep Reading

Biology

Researchers uncover 92 fossil nests belonging to some of India’s largest dinosaurs

By ScientifiCult 18 January 2023

Researchers uncover 92 fossil nests belonging to some of India’s largest dinosaurs

Fossilized eggs reveal details of titanosaur reproduction, nesting, and early life

(A) Completely unhatched egg from the clutch P43. (B) Almost fully intact circular outline of egg possibly indicating it to be unhatched and no loose eggshells are found in the clutch P6. (C) Compressed egg from clutch DR10 showing hatching window (arrow showing gap) and few eggshells collected just around the hatching window (circled) which possibly represent the remnants of hatching window. (D) Egg from clutch P26 showing curved outline. (E) Deformed egg from clutch P30 showing egg surfaces slipping past each other. Credits: Dhiman et al., 2023, PLOS ONE, CC-BY 4.0

The discovery of more than 250 fossilized eggs reveals intimate details about the lives of titanosaurs in the Indian subcontinent, according to a study published January 18, 2022 in the open-access journal PLOS ONE by Harsha Dhiman of the University of Delhi, New Delhi and colleagues.

The Lameta Formation, located in the Narmada Valley of central India, is well-known for fossils of dinosaur skeletons and eggs of the Late Cretaceous Period. Recent work in the area uncovered 92 nesting sites containing a total of 256 fossil eggs belonging to titanosaurs, which were among the largest dinosaurs to have ever lived. Detailed examination of these nests has allowed Dhiman and colleagues to make inferences about the life habits of these dinosaurs.

Researchers uncover 92 fossil nests belonging to some of India’s largest dinosaurs. It is inferred that some of the clutches were laid close to the banks of the aquatic bodies (lakes/ponds) while others were deposited away from the lakes or ponds. The clutches laid close to the margins were prone to frequent submergence by water and thus got buried under sediment and remained unhatched, while the clutches laid away from the margins could hatch and hence showed more broken eggshells. Credits: Dhiman et al., 2023, PLOS ONE, CC-BY 4.0

The authors identified six different egg-species (oospecies), suggesting a higher diversity of titanosaurs than is represented by skeletal remains from this region. Based on the layout of the nests, the team inferred that these dinosaurs buried their eggs in shallow pits like modern-day crocodiles. Certain pathologies found in the eggs, such as a rare case of an “egg-in-egg”, indicate that titanosaur sauropods had a reproductive physiology that parallels that of birds and possibly laid their eggs in a sequential manner as seen in modern birds. The presence of many nests in the same area suggests these dinosaurs exhibited colonial nesting behavior like many modern birds. But the close spacing of the nests left little room for adult dinosaurs, supporting the idea that adults left the hatchlings (newborns) to fend for themselves.

Details of dinosaur reproductive habits can be difficult to determine. These fossil nests provide a wealth of data about some of the largest dinosaurs in history, and they come from a time shortly before the age of dinosaurs came to an end. The insights gleaned from this study contribute significantly to paleontologists’ understanding of how dinosaurs lived and evolved.

Harsha Dhiman, lead author of the research, adds: “Our research has revealed the presence of an extensive hatchery of titanosaur sauropod dinosaurs in the study area and offers new insights into the conditions of nest preservation and reproductive strategies of titanosaur sauropod dinosaurs just before they went extinct.”

Guntupalli V.R. Prasad, co-author and leader of the research team, adds: “Together with dinosaur nests from Jabalpur in the upper Narmada valley in the east and those from Balasinor in the west, the new nesting sites from Dhar District in Madhya Pradesh (Central India), covering an east-west stretch of about 1000 km, constitute one of the largest dinosaur hatcheries in the world.”

Bibliographic information:

Dhiman H, Verma V, Singh LR, Miglani V, Jha DK, Sanyal P, et al. (2023) New Late Cretaceous titanosaur sauropod dinosaur egg clutches from lower Narmada valley, India: Palaeobiology and taphonomy. PLoS ONE 18(1): e0278242. https://doi.org/10.1371/journal.pone.0278242

Press release from PLOS – Public Library of Science

Keep Reading

Biology

Fossils reveal dinosaurs of prehistoric Patagonia

By ScientifiCult 11 January 2023

Fossils reveal dinosaurs of prehistoric Patagonia

A study led by The University of Texas at Austin is providing a glimpse into dinosaur and bird diversity in Patagonia during the Late Cretaceous, just before the non-avian dinosaurs went extinct.

The fossils represent the first record of theropods — a dinosaur group that includes both modern birds and their closest non-avian dinosaur relatives — from the Chilean portion of Patagonia. The researchers’ finds include giant megaraptors with large sickle-like claws and birds from the group that also includes today’s modern species.

“The fauna of Patagonia leading up to the mass extinction was really diverse,” said lead author Sarah Davis, who completed this work as part of her doctoral studies with Professor Julia Clarke at the UT Jackson School of Geosciences Department of Geological Sciences. “You’ve got your large theropod carnivores and smaller carnivores as well as these bird groups coexisting alongside other reptiles and small mammals.”

The study was published in the Journal of South American Earth Sciences.

Since 2017, members of the Clarke lab, including graduate and undergraduate students, have joined scientific collaborators from Chile in Patagonia to collect fossils and build a record of ancient life from the region. Over the years, researchers have found abundant plant and animal fossils from before the asteroid strike that killed off the dinosaurs.

The study focuses specifically on theropods, with the fossils dating from 66 to 75 million years ago.

Non-avian theropod dinosaurs were mostly carnivorous, and include the top predators in the food chain. This study shows that in prehistoric Patagonia, these predators included dinosaurs from two groups — megaraptors and unenlagiines.

Reaching over 25 feet long, megaraptors were among the larger theropod dinosaurs in South America during the Late Cretaceous. The unenlagiines — a group with members that ranged from chicken-sized to over 10 feet tall — were probably covered with feathers, just like their close relative the velociraptor. The unenlagiinae fossils described in the study are the southernmost known instance of this dinosaur group.

The bird fossils were also from two groups — enantiornithines and ornithurines. Although now extinct, enantiornithines were the most diverse and abundant birds millions of years ago. These resembled sparrows — but with beaks lined with teeth. The group ornithurae includes all modern birds living today. The ones living in ancient Patagonia may have resembled a goose or duck, though the fossils are too fragmentary to tell for sure.

The researchers identified the theropods from small fossil fragments; the dinosaurs mostly from teeth and toes, the birds from small bone pieces. Davis said that the enamel glinting on the dinosaur teeth helped with spotting them among the rocky terrain.

Some researchers have suggested that the Southern Hemisphere faced less extreme or more gradual climatic changes than the Northern Hemisphere after the asteroid strike. This may have made Patagonia, and other places in the Southern Hemisphere, a refuge for birds and mammals and other life that survived the extinction. Davis said that this study can aid in investigating this theory by building up a record of ancient life before and after the extinction event.

Study co-author Marcelo Leppe, the director of the Antarctic Institute of Chile, said that these past records are key to understanding life as it exists today.

“We still need to know how life made its way in that apocalyptic scenario and gave rise to our southern environments in South America, New Zealand and Australia,” he said. “Here theropods are still present — no longer as dinosaurs as imposing as megaraptorids — but as the diverse array of birds found in the forests, swamps and marshes of Patagonia, and in Antarctica and Australia.”

The research was funded by the National Science Foundation, the National Agency for Research and Development of Chile, and the Jackson School of Geosciences.

The study’s co-authors include Clarke and researchers at the University of Chile, Major University, the University of Concepción and the Chilean National Museum of Natural History.

The researchers in Patagonia in 2017. Lead author Sarah Davis is in the center of the front row in a blue jacket. The researchers include members from the Jackson School of Geosciences, INACH, the University of Chile, and the University of Concepción. Credits: Sarah Davis

Bibliographic information:

New records of Theropoda from a Late Cretaceous (Campanian-Maastrichtian) locality in the Magallanes-Austral Basin, Patagonia, and insights into end Cretaceous theropod diversity, Journal of South American Earth Sciences (30-Dec-2022), DOI:
10.1016/j.jsames.2022.104163

Press release from The University of Texas at Austin

Keep Reading

Biology

Bashanosaurus primitivus: the oldest stegosaurs in Asia

By ScientifiCult 6 March 2022

New species of stegosaur is oldest discovered in Asia, and possibly the world

Bashanosaurus primitivus roamed the earth around 168 million years ago during the Middle Jurassic period, suggesting that stegosaurs may have originated in Asia

Bashanosaurus primitivus species Stegosaurs Asia — Bashanosaurus primitivus – the newest and oldest species of stegosaur in Asia. *Bashanosaurus primitivus* roamed the earth around 168 million years ago during the Middle Jurassic period, suggesting that stegosaurs may have originated in Asia. Credits: Credit Banana Art Studio

Relatively small, but fearsome-looking stegosaur measured about 2.8 metres (9 feet) from nose to tail—but scientists can’t tell whether the remains are those of an adult or juvenile.

A new species of one of the most recognisable types of dinosaur is the oldest stegosaur ever found in Asia, and one of the earliest unearthed anywhere in the world, according to research published today in the peer-reviewed Journal of Vertebrate Paleontology.

Remains of the stegosaur, which included bones from the back, shoulder, thigh, feet, and ribs, as well as several armour plates, date to the Bajocian stage of the Middle Jurassic period – much earlier than most known stegosaurs.

A team from the Chongqing Bureau of Geological and Mineral Resource Exploration and Development in China and London’s Natural History Museum named it Bashanosaurus primitivus – “Bashan” in reference to the ancient name for the area of Chongqing in China where the dinosaur was found, and the Latin for ‘first’ – primitivus.

The new dinosaur, which roamed the planet 168 million years ago, plays a part in uncovering how the stegosaurs evolved – of which, to this day, little is known.

It has a smaller and less developed should blade, narrower and thicker bases to its armour plates and other features that are different from all other Middle Jurassic stegosaurs discovered so far. However, it does have similarities with some of the first armoured dinosaurs, which are over 20 million years older.

“All these features are clues to the stegosaurs’ place on the dinosaur family tree”, says Dr Dai Hui from Chongqing Bureau of Geological and Mineral Resource Exploration and Development who led the research. “Bashanosaurus can be distinguished from other Middle Jurassic stegosaurs, and clearly represents a new species.

“What’s more, our analysis of the family tree indicates that it is one of the earliest-diverging stegosaurs along with the Chongqing Lizard (Chungkingosaurus) and Huayangosaurus. These were all unearthed from the Middle to Late Jurassic Shaximiao Formation in China, suggesting that stegosaurs might have originated in Asia”, adds Hui.

Instantly recognisable by the huge back plates, long tail spikes and tiny head, stegosaurs were four-legged, plant-eating dinosaurs that lived during the Jurassic and early Cretaceous periods. Stegosaur fossils have been found on all continents except for Antarctica and Australia, and 14 species of stegosaur have been identified so far.

Well-known members of Stegosauria include Huayangosaurus (one of the most primitive stegosaurs), Gigantspinosaurus, notable for its enormous shoulder spines, and Miragaia for its extremely long neck. However, the fragmentary fossil material has hindered attempts to understand how the stegosaurs evolved and how they relate to one another.

With the discovery of this new species the mystery has started to clear up. Bashanosaurus primitivus has several primitive features that are similar to the earliest stegosaurs like Huayangosaurus and Gigantspinosaurus and early-branching thyreophorans (armoured dinosaurs). These include longer tail vertebrae, a shoulder blade that is narrower and flares out, and features of the back vertebrae that are similar to the early armoured dinosaur Scelidosaurus, which lived during the Early Jurassic.

The fossilised remains of Bashanosaurus also reveal a host of features that make it unique from other known stegosaurs. For example, the bony point at the end of the shoulder blade is small and less well developed than in other stegosaurs; a bony projection of the thighbone (fourth trochanter) is positioned below the middle of the shaft; and the bases of the armour plates curve outwards and are thicker than the plates on the backs of its later relatives.

“The discovery of this stegosaur from the Middle Jurassic of China adds to an increasing body of evidence that the group evolved in the early Middle Jurassic, or perhaps even in the Early Jurassic, and as such represent some of the earliest known bird-hipped dinosaurs,” says Dr Susannah Maidment, co-author and palaeontologist at London’s Natural History Museum.

“China seems to have been a hotspot for stegosaur diversity, with numerous species now known from the Middle Jurassic right the way through until the end of the Early Cretaceous period.”

New stegosaurs from the Middle Jurassic Lower Member of the Shaximiao Formation of Chongqing, China, Journal of Vertebrate Paleontology (4/03/2022), DOI: 10.1080/02724634.2021.1995737

Press release from Taylor & Francis Group.

Keep Reading