As reported by the Guardian on December 14, one of the world’s most famous hominin fossils may be a previously unidentified species of human ancestor. Nicknamed “Little Foot,” the skeleton was discovered between 1994 and 1998 in the Sterkfontein cave system in South Africa. It is the most complete specimen ever found of the genus Australopithecus, from which humans are descended.

Little Foot was a bipedal like humans, but likely foraged and slept in trees like primates, while the shape of the hand is more human than primate. Dating of the specimen has been difficult, with estimates ranging from 2.2 million years to 3.67 million years old.

Roland J. Clarke, a paleoanthropologist at the University of the Witwatersrand who led the 20-year excavation of Little Foot, first identified it as probably belonging to, or related to, the species Australopithecus africanus, specimens of which have been found in the same cave complex. Noting differences between Little Foot and the africanus specimens, however, he later suggested that the skeleton was of the species Australopithecus prometheus.