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The fossil of an unusual saber-toothed predator that lived during Earth’s worst mass extinction event reveals how precarious things were for animals during the Great Death.
A chain of supervolcanoes erupted in Eurasia 250 million years ago at the end of the Permian period, releasing greenhouse gases and causing catastrophic climate change. The planet’s temperature rose and oxygen in the oceans and atmosphere decreased – and around 90% of life on Earth disappeared, paving the way for dinosaurs to emerge and rule the planet until its extinction 66 million years ago.
But the Permian mass extinction event didn’t happen overnight. Instead, it spread more than a million years ago, leading researchers to dub the event the “great death”.
The fossil record acts like a time capsule, and the bones reveal a wide variety of animals struggling to survive as their environment changed around them. One such creature was the saber-toothed Inostrancevia, a mammalian ancestor about the size of a leopard, with rhino or elephant skin, somewhat reptile-like.
Inostrancevia fossils found in South Africa’s Karoo Basin.
Scientists first discovered the fossils of two specimens in 2010 and 2011 in South Africa’s Karoo Basin. After years of preparing the fossils—cleaning them, putting them together like puzzles, and piecing them together using snaps and drills—researchers were finally able to study the creature in detail.
The large fossils, including skulls, ribs, vertebrae and leg bones, surprised the team because they looked like they belonged to Inostrancevia, one of the planet’s earliest toothed predators, whose fossils have only been found in Russia. The researchers’ findings were published Monday in the journal Current Biology.
All large predators became extinct at the end of the Permian in southern Africa before the mass extinction at the end of the Permian. “We know that a vacancy in this niche was occupied, for a short time, by Inostrancevia,” study co-author Pia Viglietti, a research scientist at the Field Museum in Chicago, said in a statement. “The fossil itself is completely unexpected.”
For the last 100 years, scientists thought that inturansives lived only in the Northern Hemisphere, and that a different group of predatory mammal ancestors lived in the Southern Hemisphere. Inostrancevia lived through a time of great upheaval, successfully migrating 7,000 miles across the supercontinent Pangea and becoming predators in different environments before eventually becoming extinct.
“Just when things started to go wrong, in the early stages of what would become the worst mass extinction in Earth’s history, the southern group died. The northern species, Inosrancevia, seems to be moving to fill that gap.” As they say, nature hates a vacuum – if there is open space in an ecosystem and the resources to support it, life will find a way. Unfortunately for Inostrancevia, things soon got so bad that they (and most other organisms) went extinct as well.”
Studying the Karoo Basin is helping scientists piece together what happened during the Permian mass extinction.
The Inosrancevia fossils were found on a farm called Nooitgedacht in South Africa’s Karoo Basin.
“The Karoo Basin holds the best record for life on Earth before and after the mass extinction,” said Kammerer. “Nowhere else has so many fossils from the relevant time periods (tens of thousands of skulls and skeletons collected) or so extensive a continuous exposure of rock across the extinction threshold.”
While the basin only represents what was happening in that part of the world at the time, excavations reveal how the setting of Inostrancevia foreshadows what was to come when important roles in ecosystems shifted due to loss of species. That’s more complicated than when an asteroid wiped out the dinosaurs, giving rise to mammals.
Kammerer said the fossil record shows that around 251.9 million years ago, the dividing line between the Permian and Triassic periods, four different groups of animals alternated as primary predators, went extinct and then replaced them. That’s a high turnover rate in two million years compared to the way animal groups function today.
“Today, for example, the top predators in most terrestrial environments are carnivorous mammals (such as cats, dogs and bears), and this was about 25 million years ago,” he says. “What we’re seeing about the Permian extinction is the occupation of an apex predator role—a position at the top of the food chain—which changed very quickly, over two million years or less. This suggests a fundamentally unstable biosphere.”
Kammerer said apex predators were some of the groups most vulnerable to extinction because they were slower to reproduce and grow and needed large areas to roam and hunt, such as wolves in Europe and tigers in Asia.
Fossils from Russia and South Africa tell part of the story of Inostrancevia, but researchers want to know what happened during the great migration between the two regions. Another promising fossil site in North Africa could fill that knowledge gap and reveal more information about how the animal lived.
“Protomammals are a strange group of organisms, not reptiles, but not yet mammals, and it’s hard to imagine how they actually functioned, which is why good fossils and detailed studies of them are so important,” said Kammerer.
The researchers say that studying what happened during the greatest loss of biodiversity on Earth in millions of years could serve as a mirror for what is happening globally now because of the climate crisis.
“It’s always good to get a better understanding of how mass extinction events affected ecosystems, especially since the Permian period basically parallels what we are experiencing now,” said Viglietti.
“We don’t really have recent analogues of what to expect with the mass extinction that’s happening today, and the Permo-Triassic mass extinction event is one of the best examples of what we can have with climate crises and extinctions,” he said. . . .
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