The future of life on Earth was bleak. At the conclusion of the Permian Period, around 252 million years ago, runaway global warming brought on by catastrophic volcanism in Siberia caused the largest mass extinction on record, wiping out perhaps 90% of all species.

Unlike the asteroid that wiped out the dinosaurs 66 million years ago, this extinction event took place over a long period of time, with species dying off one by one as the situation grew worse. Scientists said on Monday that fossils discovered in South Africa offer a glimpse into this drama, telling the story of an apex predator that travelled halfway around the globe over several generations in a last-ditch effort to live.

Prior to additional bones being found at a farm in central South Africa, information about this creature, a tiger-sized, saber-toothed mammal precursor known as Inostrancevia, had only been gleaned from fossils discovered in Russia's northwest corner bordering the Arctic Sea.

The fossils indicate that Inostrancevia left its home region and journeyed over time—possibly hundreds or thousands of years—across the ancient supercontinent Pangaea, when the continents of today were united, covering around 7,000 miles (12,000 km). After four other species had previously gone extinct in South Africa, Inostrancevia filled the ecological void left by the top predator.

Inostrancevia and all of its closest relatives perished in the mass extinction known as "the Great Dying," according to palaeontologist Christian Kammerer of the North Carolina Museum of Natural Sciences, who is also the lead author of the study that was published in the journal Current Biology.

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

Inostrancevia is a member of the group of creatures known as protomammals, which combines characteristics of both reptiles and mammals. It was around the size of a Siberian tiger, 10 to 13 feet (3 to 4 meters) long, but had a proportionately larger and elongated cranium, as well as massive, blade-like canine fangs.

According to Kammerer, "I think these animals mostly killed prey with their saber-like canine fangs and either carved out chunks of meat with the serrated incisors or, if the prey was small enough, swallowed the prey whole."

The body of Inostrancevia possessed a peculiar position that was characteristic of protomammals; it was neither sprawled like a reptile nor erect like a mammal, but rather a combination of the two, with splayed forelimbs and mainly erect rear limbs. In addition, it lacked the face muscles found in mammals and was incapable of lactation.

"Whether these animals were furry or not remains an open question," stated Kammerer.

The mass extinction, which took place over the course of about a million years, prepared the way for the emergence of dinosaurs during the following Triassic Period. Large-scale volcanism unleashed lava flows throughout much of Eurasia and released tons of carbon dioxide into the atmosphere for a very long time. Global desertification, an increase in ocean acidification, a rise in global temperatures, and a decrease in atmospheric and oceanic oxygen content were all brought on by this.

Because they needed the greatest food and area, top predators were particularly susceptible to extinction.

They have a propensity to grow slowly and produce few progeny. Top predators are disproportionately impacted when ecosystems are disrupted, prey supplies are diminished, or there is a lack of adequate habitat, according to Kammerer.

The Permian catastrophe and the current, human-caused climate change are comparable in the eyes of the academics.

These species were directly impacted by the climate disaster brought on by global warming, thus they truly had no alternative but to adapt or perish. The fact that they survived for a short time despite these circumstances clearly demonstrates this, but eventually they all vanished, according to research co-author and paleontologist Pia Viglietti of the Field Museum in Chicago.

Viglietti continued, "Unlike our Permian forebears, we actually have the potential to do something to stop this kind of ecosystem collapse from occurring again."