Larger than a tiger, lion, or polar bear with a skull comparable with a rhinoceros, this ancient predator cat, known as Simbakubwa kutokaafrika, wasn't discovered in the field—but in a long-neglected museum drawer.
Paleontologists Nancy Stevens and Matthew Borths at Ohio University discovered the new species of large meat-eating mammal, at the National Museums of Kenya. They had been previously excavated within the country, and were "not given a great deal of attention," according to a from Ohio University.
"Opening a museum drawer, we saw a row of gigantic meat-eating teeth, clearly belonging to a species new to science," says study lead author Borths in the press statement.
"The most striking feature of Simbakubwa is the size of the specimen," reads. "Based on its massive dentition, the animal was significantly larger than any modern African terrestrial carnivore." Dentition refers to the development of teeth, a key element of studying ancient fossils.
Using known methods of extrapolating body mass from teeth, scientists estimate that the big cat weighed approximately 1,308 kilograms, or an astonishing 2,888 pounds. For comparison, modern adult lions and tigers weigh approximately 180 kg, or 400 pounds.
The Simbakubwa was part of an extinct group of mammals called hyaenodonts, which were apex predators in Africa for 45 million years after the extinction of the non-avian dinosaurs.
As in any ecosystem, apex predators had a crucial role in the era known to paleontologists as the Oligocene, a period of global transition between the world of the dinosaurs, which had been destroyed an annihilation event, and the modern ecosystems known today. On the African continent, the Simbakubwa any herbivore species, including , from dominating the landscape.
While hyaenodonts lived in various environments across the globe, they went extinct between 15 to 18 millions ago. Scientists are still unsure of the precise reasons, but their extinction came at a further moment of change, when their forests began a transformation into grasslands. Big predator cats can still be found in grasslands today, though they by yet another moment of changing climate.
"We don't know exactly what drove hyaenodonts to extinction, but ecosystems were changing quickly as the global climate became drier," says Borths. "The gigantic relatives of Simbakubwa were among the last hyaenodonts on the planet."
"This is a pivotal fossil, demonstrating the significance of museum collections for understanding evolutionary history," says Stevens, a co-author of the study. "Simbakubwa is a window into a bygone era. As ecosystems shifted, a key predator disappeared, heralding Cenozoic faunal transitions that eventually led to the evolution of the modern African fauna."