South African fossils reveal ancient beast's epic journey to oblivion

New remains of a tiger-sized, saber-toothed protomammal were discovered at a farm in central South Africa

It was a dire moment for life on Earth. Runaway global warming triggered by calamitous volcanism in Siberia inflicted the worst mass extinction on record - dooming perhaps 90% of species - roughly 252 million years ago at the end of the Permian Period.

Unlike the asteroid 66 million years ago that ravaged the dinosaurs, this extinction event unfolded over a protracted time span, with species perishing one by one as conditions worsened. Scientists said on Monday fossils unearthed in South Africa provide a peek into this drama, telling the tale of an apex predator that over multiple generations migrated halfway around the world in a desperate, and ultimately failed, bid to survive.

This beast, a tiger-sized, saber-toothed mammal forerunner called Inostrancevia, had been known only from fossils excavated in Russia's northwestern corner bordering the Arctic Sea until new remains were discovered at a farm in central South Africa.

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The fossils suggest that Inostrancevia left its place of origin and trekked over time - maybe hundreds or thousands of years - about 7,000 miles (12,000 km) across Earth's ancient supercontinent Pangaea at a time when today's continents were united. Inostrancevia filled the ecological niche of top predator in South Africa left vacant after four other species already had vanished.

"However, it did not survive there long," said palaeontologist Christian Kammerer of the North Carolina Museum of Natural Sciences, lead author of the research published in the journal Current Biology, noting that Inostrancevia and all of its closest relatives disappeared in the mass extinction called "the Great Dying."

"So, they have no living descendants, but they are a member of the larger group called synapsids, which includes mammals as living representatives," Kammerer added.