Life on Earth had a grim future. The largest mass extinction on record—wiping out possibly 90% of all species—occurred during the end of the Permian Period, around 252 million years ago, as a result of rapid global warming spurred on by catastrophic volcanism in Siberia.
In contrast to the catastrophic asteroid impact 66 million years ago that led to the demise of the dinosaurs, the current extinction event took place gradually, spanning an extended period. As conditions deteriorated, species succumbed to their demise individually rather than all at once. Recent findings from excavated fossils in South Africa shed light on this unfolding drama, revealing the story of an apex predator.
Across multiple generations, this creature embarked on a perilous journey, migrating halfway around the globe in a desperate attempt to ensure its survival. However, this endeavor ultimately proved futile, marking a tragic end to its struggle.
Inostrancevia, a tiger-sized, saber-toothed mammal predecessor, had only been known from fossils unearthed in Russia's northwest, near the Arctic Sea, until more bones were discovered at a farm in central South Africa.
The fossil evidence reveals that Inostrancevia undertook a remarkable journey, spanning a significant period—potentially spanning hundreds or even thousands of years—across the prehistoric supercontinent Pangaea. This vast migration covered an astonishing distance of approximately 7,000 miles (12,000 km), during a time when the modern-day continents were interconnected. Following the extinction of four other species in South Africa, Inostrancevia successfully occupied the ecological vacuum left by the previous apex predator, becoming the new dominant force in the region.
"Regrettably, its stay in that location was short-lived," explained paleontologist Christian Kammerer from the North Carolina Museum of Natural Sciences, who served as the lead author of the study published in the journal Current Biology. Kammerer emphasized that Inostrancevia, along with its nearest kin, fell victim to the catastrophic event known as "the Great Dying," resulting in their complete extinction.
Kammerer added that the extinct species under discussion, despite having no living descendants, belonged to a larger group called synapsids, which presently includes mammals as their living representatives.
The group of organisms known as protomammals, which combines traits of both reptiles and mammals, includes Inostrancevia. It was roughly the size of a Siberian tiger, measuring 10 to 13 feet (3 to 4 meters) long, but it also had gigantic, blade-like canine teeth and a proportionately larger and elongated head.
According to Kammerer, it is believed that these creatures primarily hunted their prey using their saber-like canine fangs. They would either tear off chunks of meat using their serrated incisors or, if the prey was small enough, swallow it whole.
Inostrancevia's body was positioned in an unusual way that was typical of protomammals; it wasn't upright like a mammal or sprawled like a reptile, but rather was a hybrid of the two, with splayed forelimbs and primarily erect rear limbs. Additionally, it was incapable of lactating and lacked the facial muscles common to mammals.