The Svalbard bonebed is much more diverse than any other known site of the same age. © Robert Back
By James Ashworth
Over 250 million years ago the planet went through the worst mass extinction in history.
In the aftermath, life took millions of years to recover. But newly uncovered fossils on an Arctic island suggest that, in some places, it bounced back much quicker than expected.
You might not expect to the find the remnants of an ancient ocean partway up a mountain – but that’s exactly what’s happened in Svalbard.
Scientists working on the Arctic archipelago’s largest island, Spitsbergen, uncovered a 249-million-year-old bonebed on the side of Mount Marmier. They estimate that it contains more than 30,000 marine fossils, including bones, teeth and fossilised poo, known as coprolites.
These remains offer an unprecedented opportunity to study how the oceans recovered in the aftermath of the Permian mass extinction, which wiped out almost all life on Earth around 252 million years ago. Unexpectedly, the fossils show that the seas around what’s now Svalbard were already thriving just a few million years later.
Dr Aubrey Roberts, our Scientific Associate who led the research, says that the fossils include the remnants of a wide range of bony fishes, sharks and marine reptiles. It suggests that some areas of the world recovered more quickly from the mass extinction than others.
“Fossil sites in China showed signs of a gradual recovery from the Permian mass extinction over a period of about eight million years,” Aubrey explains. “What we’ve found in Svalbard is quite a different story.”
“Just three million years after the extinction, there’s already an extraordinary variety of animals from fish and sharks to marine amphibians and reptiles. This is a very rich ecosystem, and one that’s going to keep us going for decades to come.”
The findings of the study were published in the journal Science.
The Putorana Plateau is one of the rocky outcrops of the Siberian Traps, which erupted over 250 million years ago. © Lebedev Sergei/ Shutterstock
As the Permian Period came to an end, the world changed drastically.
A volcanic region in what is now Russia, known as the Siberian Traps, erupted and emitted vast amounts of greenhouse gases that caused severe climate change around the world.
This had a particularly heavy impact on the oceans, with water temperatures near the equator estimated to have exceeded 40°C. Warmer water holds less oxygen, so it’s thought that many marine animals simply stopped being able to breathe.
At the same time, the higher levels of carbon dioxide dissolving into the ocean made the water more acidic, which would have eaten away at the shells and skeletons of many different creatures.
With up to 95% of marine life wiped out, it might seem reasonable to assume that the oceans took time to recover. Marine reptile fossils from the Early Triassic are rare, leading some scientists to suggest it took several million years for these animals to dominate the oceans.
Millions of years of tectonic activity mean what was once the seabed is now on the side of Mount Marmier. © University of Oslo
The Svalbard bonebed, however, suggests that might not have been the case everywhere. Found in 2014, its remote location means that it has taken more than a decade for the first research to emerge from the site.
“It’s taken years to excavate this bonebed,” Aubrey recalls. “As it’s on a mountain in the Arctic Circle, studying it was quite a challenge at times!”
“We ended up studying a lot of the bonebed in situ while we were taking other sections out.”
The bonebed contains fossils from a variety of animals, which were probably swept into a deep part of the seafloor by ocean currents. The diversity of remains suggests that these organisms were part of an ecosystem that was bursting with life, rather than struggling to survive.
Near the bottom of the food chain, squid, fish and jawless animals known as conodonts were abundant. These were the food for predatory fish such as Birgeria and an early relative of ichthyosaurs known as Grippia.
Other predators were specialised shell-eaters, such as the Lissodus sharks and the marine reptile Omphalosaurus. These used their teeth to grind through the tough outer layers of hard-shelled ammonites.
All of these animals would have been fed on by Cymbospondylus. The sharp and ridged teeth of this early ichthyosaur would have enabled it to tear through the flesh of fishes, marine reptiles and other animals, making it the ecosystem’s apex predator.
Temnospondyls reached their peak in the Early Triassic, with a few species managing to survive into the Cretaceous. © DiBgd via Wikimedia Commons, licensed under CC BY-SA 3.0.
The ecosystem also had some more unexpected members – large, ancient amphibians known as temnospondyls.
“It’s quite surprising to find marine temnospondyls here, as we don’t normally find them alongside marine reptiles,” Aubrey explains. “Their fossils are quite rare in the bonebed, at least in comparison to the reptiles, which suggests a couple of possibilities.”
“On the one hand, the temnospondyls might have been living nearer to the shore, and the fossils we see here are of the individuals that strayed further out. On the other hand, they might have been outcompeted by the reptiles and their scarcity could represent the tail end of the temnospondyls in this region. At the moment, it’s just not clear.”
The team has only studied a small fraction of the bonebed, and hope that questions such as this will become clearer as they delve deeper into it. They’re also planning on searching for more fossil sites on Svalbard.
“There’s still so much left to study, and we’re planning to start work on the different types of teeth we’ve found to see what that reveals about the animals that lived here and their relationships,” Aubrey adds.
“We’re also going to be focusing on the coprolites, and have taken CT scans because this can reveal really amazing details about what animals were eating all that time ago. Our research has only scratched the surface so far, and we look forward to exploring everything else this site has to reveal.”
Find out more about why we need to protect oceans and read about the pioneering work of our marine scientists.
Don't miss a thing
Receive email updates about our news, science, exhibitions, events, products, services and fundraising activities. We may occasionally include third-party content from our corporate partners and other museums. We will not share your personal details with these third parties. You must be over the age of 13. Privacy notice.
Follow us on social media