Earth’s worst extinction was followed by a shockingly fast ocean comeback

The fossils were first discovered in 2015, but transforming them into scientific evidence required nearly ten years of careful excavation, preparation, sorting, identification, and analysis. The results of this long effort have now been published by researchers from the Natural History Museum at the University of Oslo and the Swedish Museum of Natural History in Stockholm.

Why Spitsbergen Is a Paleontological Hotspot

Spitsbergen, part of the Svalbard archipelago, is internationally known for its exceptionally preserved marine fossils from the early Age of Dinosaurs. These remains are locked within rock layers that began as soft mud on the seafloor, formed in an ancient ocean that stretched across mid to high paleolatitudes and bordered the massive Panthalassa Super-ocean.

Among the most striking finds are the fossils of unusual marine reptiles and amphibians. These animals represent some of the earliest examples of land-based species adapting to life far from shore, marking a critical turning point in vertebrate evolution.

Life After the End-Permian Mass Extinction

According to long-standing textbook explanations, this evolutionary shift occurred after the most devastating extinction event in Earth History, which happened about 252 million years ago. Known as the end-Permian mass extinction, this event, often called the 'great dying', eliminated more than 90 percent of marine species. Scientists link the catastrophe to intense greenhouse conditions, oxygen loss in the oceans, widespread acidification, and massive volcanic eruptions tied to the breakup of the ancient Pangaean supercontinent.

How quickly marine ecosystems recovered after this disaster has been one of the most hotly debated questions in paleontology. The prevailing theory suggested a slow rebound that unfolded over roughly eight million years, with amphibians and reptiles gradually moving into open ocean environments in a step-by-step process. The fossil evidence from Spitsbergen now challenges that assumption.

A Bonebed Packed With Ancient Life

The newly studied fossil deposit on Spitsbergen is so concentrated that it forms a visible bonebed eroding out of the mountainside. This layer built up over a short geological interval, offering a rare snapshot of marine life just a few million years after the end-Permian mass extinction. Geological dating places the formation of the bonebed at around 249 million years ago.

Researchers collected fossils using 1 m² grid sections across a total area of 36 m², a method that ensured detailed documentation of the site. In total, more than 800 kg of material was recovered. The collection includes tiny fish scales, shark teeth, massive marine reptile bones, and even coprolites (fossilized feces).

A Rapid and Unexpected Ocean Recovery

The Spitsbergen bonebed shows that marine ecosystems rebounded far more quickly than previously believed. Within as little as three million years after the end-Permian mass extinction, the oceans supported complex food webs filled with predatory reptiles and amphibians.

One of the most surprising findings is the wide range of fully aquatic reptiles present at the site. These included archosauromorphs (distant relatives of modern crocodiles) as well as diverse ichthyosaurs ('fish-lizards'). Some species were small, squid-eating hunters measuring less than 1 m long, while others were enormous apex predators exceeding 5 m in length.

Rethinking the Origins of Marine Reptiles

A computer-based global comparison of marine animal groups underscores the importance of the Spitsbergen site. The analysis identifies the bonebed as one of the most species-rich marine vertebrate (backboned animal) assemblages known from the early Age of Dinosaurs.

The findings also suggest that the transition of reptiles and amphibians into marine environments began earlier than scientists once thought and may have started even before the end-Permian mass extinction. This 'ecosystem reset' likely created new feeding opportunities and set the stage for the structure of modern marine ecosystems.

Publication and Public Display

The study appears as a cover feature in the international journal Science. Fossils from the Spitsbergen discovery are now on public display at the University of Oslo Natural History Museum and the Swedish Museum of Natural History.