A 9.5-million-year-old jaw from when Africa was nearly devoid of apes. Possibly an ancestor of the African great apes that survived a mass extinction.
Ghedoghedo, CC BY-SA 3.0, via Wikimedia Commons
A fossil from the gap
In 1982, a Joint Japan-Kenya Expedition was searching the Samburu Hills of northern Kenya. The team discovered a fossilized left maxilla, or upper jaw bone, complete with its postcanine teeth. Cataloged as KNM-SH 8531, the specimen belonged to a previously unknown genus of extinct ape. Researchers named it Samburupithecus kiptalami.
Radiometric dating of the geological formation where it was found, the Namurungule Formation, placed the fossil at approximately 9.5 million years old. This date places it squarely in the Late Miocene epoch, a period with a very sparse African hominoid fossil record sometimes called the "African ape gap," which lasted from about 14 to 7 million years ago. Before the discovery of Samburupithecus and a few other contemporary apes like Nakalipithecus, this period was a near-blank in the story of ape evolution in Africa.
A gorilla-sized fruit eater
The jaw of Samburupithecus indicates it was a large primate, estimated to weigh around 60 kilograms (130 lbs), comparable in size to a modern female gorilla. Analysis of its dental anatomy provides clues about its life. The molars are robust, with low, rounded cusps and a thick coating of enamel. This dental structure suggests a diet that included tough, fibrous vegetation and hard objects, a departure from the soft-fruit diet of many earlier apes.
Paleoenvironmental reconstructions show that 9.5 million years ago, this part of Kenya was a wooded habitat surrounded by savannah. The strong jaw and specialized teeth of Samburupithecus were well-suited for processing the challenging plant materials found in such an environment. Its cranial features, such as low, broad cheekbones and a large maxillary sinus, further distinguish it from other known Miocene apes.
The evolutionary position of Samburupithecus is still debated. Its unique mix of features has led to several hypotheses. Some scientists suggest it could be a common ancestor to gorillas, chimpanzees, and humans, living before that lineage split. Other analyses propose it may be a late-surviving member of an older group of stem hominoids. Regardless of its exact placement on the family tree, the fossil shows the ape diversity that persisted in Africa through a period of significant environmental change.
💡Fun Facts
The species name "*kiptalami*" honors Kiptalam Chepboi, a local man who was instrumental to the fossil-hunting expedition.
The molar enamel of *Samburupithecus* is among the thickest recorded for any Miocene ape, suggesting a diet of very hard foods.
The fossil is the only known specimen of its genus, making it an important piece of evidence.
Other fossils found in the same geological layers include ancient elephants, horses, and rhinos.
The original fossil specimen, KNM-SH 8531, is housed in the collections of the National Museums of Kenya in Nairobi and is not on public display. The museum is open daily from 8:30 a.m. to 5:30 p.m.
Admission
Check the National Museums of Kenya website for current admission fees for the Nairobi National Museum.
Accessibility
The Nairobi National Museum is wheelchair accessible. The actual fossil site in Samburu County is in a remote, rugged area and is not accessible to the public.
