Thursday, November 13, 2025

Oldest oceanic reptile ecosystem from the Age of Dinosaurs found on Arctic island

Swedish Museum of Natural History

Earliest Oceanic Tetrapod Ecosystem — image:
Earliest oceanic tetrapod ecosystem from 249 million years ago. A pod of the small-bodied ichthyopterygian ('fish-lizard') *Grippia longirostris* hunting squid-like ammonoids (top left). The marine amphibian Aphaneramma captures the bony fish Bobastrania (foreground). The gigantic ichthyosaur Cymbospondylus lurks in the depths (bottom right).
Fossil of these ancient marine reptiles and amphibians are today preserved on the Arctic island of Spitsbergen in the Svalbard archipelago.
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Credit: Robert Back

The fossils were found in 2015, but took nearly a decade of painstaking work to excavate, prepare, sort, identify, and analyse. The long-awaited research findings have now been published by a team of Scandinavian palaeontologists from the Natural History Museum at the University of Oslo, and the Swedish Museum of Natural History in Stockholm.

Spitsbergen in the Svalbard archipelago is world famous for producing marine fossils from the beginning of the Age of Dinosaurs. These are preserved in rock layers that were once mud at the bottom of a sea stretching from mid-to-high palaeolatitudes and bordering the immense Panthalassa Super-ocean. Most spectacular are the remains of bizarre marine reptiles and amphibians that represent the earliest adaptive specialisation of land-living animals for life in offshore habitats.

Textbooks suggest that this landmark evolutionary event took place after the most catastrophic mass extinction in Earth History, some 252 million years ago. Termed the end-Permian mass extinction, this ‘great dying’ wiped out over 90% of all marine species, and was driven by hyper-greenhouse conditions, oceanic deoxygenation, and acidification linked to massive volcanic eruptions initiating breakup of the ancient Pangaean supercontinent.

Timing the recovery of marine ecosystems after the end-Permian mass extinction is one of the most debated topics in palaeontology today. The long-standing hypothesis is that this process was gradual, spanning some eight million years, and involved a step-wise evolutionary progression of amphibians and reptiles successively invading open marine environments. However, discovery of the new and exceptionally rich fossil deposit on Spitsbergen has now upended this traditional view.

The Spitsbergen fossil deposit is so dense that it actually forms a conspicuous bonebed weathering out along the mountainside. This accumulated over a very short geological timeframe, and therefore provides unprecedented insights into the structure of marine communities from only a few million years after the end-Permian mass extinction. Stratigraphic dating has pinpointed the age of the Spitsbergen fossil bonebed to around 249 million years ago. Careful collection of the remains from 1 m2 grids covering 36 m2 has also ensured that over 800 kg of fossils, including everything from tiny fish scales and shark teeth to giant marine reptile bones and even coprolites (fossilized feces) were recovered.

The Spitsbergen fossil bonebed reveals that marine ecosystems bounced back extremely rapidly, and had established complex food chains with numerous predatory marine reptiles and amphibians by as little as three million years after the end-Permian mass extinction. Most surprising is the sheer diversity of fully aquatic reptiles, which included archosauromorphs (distant relatives of modern crocodiles) and an array of ichthyosaurs (‘fish-lizards’) ranging in size from small squid-hunters less than 1 m long, to gigantic apex-predators exceeding 5 m in length.

A computer-based global comparative analysis of the various animal groups further highlights the Spitsbergen fossil bonebed as one of the most species-rich marine vertebrate (backboned animal) assemblages ever discovered from the dawn of the Age of Dinosaurs. It also suggests that the origins of sea-going reptiles and amphibians are much older that previously suspected, and likely even preceded the end-Permian mass extinction. This ‘ecosystem reset’ would have opened new feeding niches, and ultimately, laid the foundations for modern marine communities as we know them today.

The paper is published as a cover feature in the prestigious international journal Science. Ancient marine reptile fossils from Svalbard are on public display at the University of Oslo Natural History Museum and Swedish Museum of Natural History.

Reference

Roberts, A.J., Rucinski, M., Kear, B.P., Hammer, Ø., Engelschiøn, V.S., Scharling, T.H., Larsen, R.B., and Hurum, J.H. (2025). Earliest oceanic tetrapod ecosystem reveals rapid complexification of Triassic marine communities. Science.

Contact information

Aubrey Roberts (lead author): a.j.roberts@nhm.uio.no

Benjamin Kear (co-author): benjamin.kear@nrm.se, +46708245679

Jørn Hurum (co-author): j.h.hurum@nhm.uio.no

Journal

Science

DOI

10.1126/science.adx7390

Method of Research

Observational study

Subject of Research

Animals

Article Title

Earliest oceanic tetrapod ecosystem reveals rapid complexification of Triassic marine communities

Article Publication Date

13-Nov-2025

Fossil dig site on the island of Spitsbergen in the Svalbard archipelago. Excavations and research involved a team of Scandinavian palaeontologists from the Natural History Museum at the University of Oslo and the Swedish Museum of Natural History in Stockholm.

Fossil excavation on the island of Spitsbergen in the Svalbard archipelago. Research involved a team of Scandinavian palaeontologists from the Natural History Museum at the University of Oslo and the Swedish Museum of Natural History in Stockholm.

Credit

Natural History Museum, University of Oslo

Earliest oceanic tetrapod ecosystem from 249 million years ago. A pod of the small-bodied ichthyopterygian ('fish-lizard') Grippia longirostris hunting squid-like ammonoids (centre). A school of the bony fish Boreosomus and Saurichthys feed in the distance.

Fossil of these ancient marine reptiles and fishes are today preserved on the Arctic island of Spitsbergen in the Svalbard archipelago.

Credit

Robert Back

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Newly discovered predatory “warrior” was a precursor of the crocodile – and although it lived before the early dinosaurs, it looked just like one

“Extremely rare” revelation of this new armour-plated carnivore reptile reinforces our knowledge of the connection between Brazil and Africa 240 million years ago

Taylor & Francis Group

Infographic (by Caio Fantini, Rodrigo Temp Müller, Mauricio Garcia) — image:
Infographic of *Tainrakuasuchus bellator*
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Credit: Caio Fantini, Rodrigo Temp Müller, Mauricio Garcia

A newly discovered, carnivorous lizard ostensibly represents what most casual onlookers would perhaps perceive to be a dinosaur; however, it is in fact a precursor of the modern crocodile.

Named Tainrakuasuchus bellator, partially derived from Latin meaning for “warrior” or “fighter”, this armour-plated reptile lived 240 million years ago just before the dinosaurs.

And, as a Pseudosuchia (the precursors of modern crocodiles and alligators), it was among a group of the top, most dominant predators of its time in the Triassic Period.

This particular new species – detailed, today, in the peer-reviewed Journal of Systematic Palaeontology – was approximately 2.4m long and weighed 60kg.

It used its long neck and agile mobility to prey on victims using quick and precise movements, before gripping its prey using its slender jaw profile full of sharp, recurved teeth to hold the target, preventing them from escaping.

“This animal was an active predator, but despite its relatively large size, it was far from the largest hunter of its time with the same ecosystem home to giants as big as seven meters long,” explains lead author Dr Rodrigo Temp Müller, who led a team of palaeontologists from the Universidade Federal de Santa Maria, in Brazil.

“Pseudosuchia were a diverse group of animals capable of tackling robust prey, as well as small hunters specialized in catching swift animals.

“Although its appearance superficially resembles that of a dinosaur, Tainrakuasuchus bellator does not belong to that group. One of the clearest ways for us to distinguish it from dinosaurs lies in the structure of the pelvis where the characteristics of its hip and femur joints are very different.”

Dr Müller adds: “Tainrakuasuchus bellator’s discovery represents the complexity of the ecosystem at the time, with different pseudosuchia species – varying in sizes and hunting strategies – occupying specific ecological niches.

“Its discovery helps illuminate a key moment in the history of life, the period that preceded the rise of the dinosaurs.”

Dr Müller and his team discovered its fossils during a dig in the municipality of Dona Francisca, in southern Brazil, during May 2025.

They unearthed, surrounded in rock, a partial skeleton preserving parts of the lower jaw, vertebral column, and pelvic girdle.

From this they could reveal many behaviours of the creature, as well as the fact that Tainrakuasuchus bellator had a back covered by bony plates known as osteoderms, structures that are also present in modern crocodiles.

And, although the limbs were not preserved, the expert team believe, alike its close relatives, it moved on all four limbs.

Its name they have given to the creature is ‘Tainrakuasuchus’ combining the Guarani words tain (“tooth”) and rakua (“pointed”) with the Greek suchus (“crocodile”), in reference to the animal’s sharp teeth.

The ‘bellator’ part of its name comes from the Latin word for “warrior” or “fighter”- which the authors state “honours the people of Rio Grande do Sul, symbolizing their strength, resilience, and fighting spirit, especially in light of the recent floods that have affected the state”.

Dr Müller describes Tainrakuasuchus bellator’s discovery as “extremely rare”. He explains it’s also further evidence of the ancient connection between Brazil and Africa during the Triassic Period – when the world’s continents were united into a single supercontinent, Pangaea.

“Despite the diversity of pseudosuchians, they remain poorly understood, as fossils of some their lineages are extremely rare in the fossil record,” Dr Müller says.

“The fossils we found underwent a meticulous preparation process in the laboratory, during which the surrounding rock was carefully removed.

“Once the anatomical details were revealed, we were delighted and really excited to reveal that the specimen represented a species previously unknown to science.

“What we uncovered was a species that belongs to a predator closely related to one (Mandasuchus tanyauchen) found in Tanzania.

“This connection between animals from South America and Africa can be understood in light of the Triassic Period’s paleogeography.

“At that time, the continents were still united, which allowed the free dispersal of organisms across regions that are now separated by oceans. As a result, the faunas of Brazil and Africa shared several common elements, reflecting an intertwined evolutionary and ecological history.

“Tainrakuasuchus bellator would have lived in a region bordering a vast, arid desert – the same setting as where the first dinosaurs emerged.

“It shows that, in what is now southern Brazil, reptiles had already formed diverse communities adapted to various survival strategies. Moreover, this discovery reveals that such diversity was not an isolated phenomenon.”