Scientists Discover Remains of an Ancient Bobcat-sized Predator in Tanzania: Pakakali rukwaensis

Thursday, October 19, 2017

Pakakali rukwaensis

“With Pakakali, we can start to unravel that extinction,” researcher Matthew Borths said. “Were the lineages competing? Were they adapting differently to a drier, more open landscape?”

Paleontologists have discovered a new species of extinct hyaenodont in Tanzania. The fossil offers new insights into the disappearance of hyaenodonts — once Africa’s top predator — during the Paleogene.

Hyaenodonts were cat-like in appearance, but walked on flat feet. After the dinosaurs bit the dust at then end of the Cretaceous period 66 million years ago, hyaenodonts became Africa’s most dominant carnivore.

Scientists named the newly discovered species Pakakali rukwaensis. “Pakakali” is a Swahili term meaning “fierce cat,” and “rukwaensis” is the Swahili name for the Rukwa Rift region in Tanzania’s Great Rift Valley, where the species’ remains were discovered.

Researchers described their discovery in a new paper, published on Wednesday, national “Fossil Day,” in the journal PLOS One.

The reign of the hyaenodonts was relatively short-lived. Around the time of Pakakali rukwaensis, between 23 and 25 million years ago, the earliest relatives of dogs, cats and hyenas emerged. These new carnivores eventually won the evolutionary race and hyaenodonts joined the dinosaurs in extinction.

“The shift from hyaenodonts to modern carnivores in Africa is like a controlled experiment,” Matthew Borths, a paleontologist at Ohio University, said in a news release. “We start with only hyaenodonts. Then the relatives of cats and dogs arrive. They coexist for a few million years, then the hyaenodonts are driven to extinction and we’re left with ‘The Lion King.'”

Because Pakakali rukwaensis arrived on the scene around the time the trajectory of the hyaenodonts began to take a turn southward, researchers believe the species could offer clues to the demise of its family.

“With Pakakali, we can start to unravel that extinction,” Borths said. “Were the lineages competing? Were they adapting differently to a drier, more open landscape?”

The new species’ fossilized skull was discovered among the same 25-million-year-old rock strata that revealed the split between Old World monkeys and apes. At the time, Africa was colliding with Eurasia, forming the East African Rift System. The tectonic shifts underpinned dramatic climate change.

At the time of Pakakali rukwaensis emergence, the bobcat-sized predators were struggling to adapt to a drier, more wide-open environment. As a result of increased competition, hyaenodonts were also forced to specialize in the consumption of meat. They weren’t able to adapt quick enough, and ultimately, they died out.

“The environment containing Pakakali reveals a fascinating window into extinction,” said Nancy Stevens, a paleontologist at Ohio University. “It highlights the vulnerability of carnivorous species to rapid environmental change, a topic we are grappling with on the African continent today.”