- From fossils kept in a drawer at Nairobi National Museum for several decades, researchers have described a new species of a giant carnivore that walked the Earth some 22 million years ago.
- The extinct carnivore was larger than any big cat that lives today, with a skull the size of a rhinoceros’s and massive canine teeth, the researchers say.
- The meat-eating mammal has been dubbed Simbakubwa kutokaafrika, or “big lion from Africa” in Swahili.
- Despite the name, the animal wasn’t a big cat or related to one. Instead, it belonged to a now-extinct group of carnivores called hyaenodonts that were once the top predators across Africa.
For a long time, some of the fossil remains that had been excavated from a site in western Kenya in the late 1970s languished in a drawer at Nairobi National Museum, unidentified. Now, by examining and piecing together the teeth, parts of a jaw, skull and skeleton, researchers have described a new species of a giant carnivore that stalked the Earth some 22 million years ago.
The extinct carnivore was larger than any big cat that lives today, researchers report in a new study published in the Journal of Vertebrate Paleontology. It had a skull the size of a rhinoceros’s and massive canine teeth. In fact, it’s well-preserved teeth suggest that the predator could have weighed as much as 1,500 kilograms (3,300 pounds), making it one of the largest terrestrial carnivorous mammals ever known, the researchers say. The animal possibly preyed on elephant- and hippopotamus-like herbivores that lived then.
The meat-eating mammal has been dubbed Simbakubwa kutokaafrika — simbakubwa in Swahili means “big lion,” while kutokaafrika means “from Africa.”
“Based on its massive teeth, Simbakubwa was a specialized ‘hypercarnivore’ that was significantly larger than the modern lion and possibly larger than a polar bear,” Matthew Borths, a paleontologist at Duke University, said in a statement. Borths conducted the research as a postdoctoral student at Ohio University.
Despite its name, the animal wasn’t a big cat or related to one. Instead, it belonged to a now-extinct group of carnivores called hyaenodonts that emerged after the mass extinction of non-avian dinosaurs some 65 million years ago. For a long time, with none of the predecessors of modern carnivores like lions around, the hyaenodonts were the top predators across Africa.
But they ultimately died out. And their extinction may have been a result of environmental changes, the researchers say. Tectonic shifts brought Africa closer to other continents, allowing for the exchange of animals and plants. The evolving East African Rift caused ocean currents to shift and the climate to change. Grasslands spread and replaced forests, which in turn allowed new mammal groups to evolve and diversify. These changes could also have led to the giant predators’ preferred large-sized preys disappearing, resulting in the hyaenodonts’ demise.
“We don’t know exactly what drove hyaenodonts to extinction, but ecosystems were changing quickly as the global climate became drier,” Borths said. “The gigantic relatives of Simbakubwa were among the last hyaenodonts on the planet.”
Co-author Nancy Stevens, a paleontologist at Ohio University and co-author of the study, said the Simbakubwa find was a pivotal fossil, “demonstrating the significance of museum collections for understanding evolutionary history.”
“Simbakubwa is a window into a bygone era,” Stevens said in the statement. “As ecosystems shifted, a key predator disappeared, heralding Cenozoic faunal transitions that eventually led to the evolution of the modern African fauna.”
Borths M. R., and Stevens, N. J. (2019) Simbakubwa kutokaafrika, gen. et sp. nov. (Hyainailourinae, Hyaenodonta, ‘Creodonta,’ Mammalia), a gigantic carnivore from the earliest Miocene of Kenya. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2019.1570222