Which extinct primate species from Kenya is known as the 'Millennium Ancestor'?

Which extinct primate species from Kenya is known as the “Millennium Ancestor”? The answer is Orrorin tugenensis.

Orrorin tugenensis is an extinct early hominin identified from fossils found in Kenya’s Tugen Hills. The nickname “Millennium Ancestor” refers to the discovery of its main fossil material around the turn of the millennium. The species was formally named in 2001; Orrorin means “original man” in the Tugen language, while tugenensis refers to the Tugen region.

The fossils come from the Lukeino Formation and date to roughly 6 million years ago, making Orrorin one of the earliest known hominins. They include jaw fragments, teeth, femur pieces, a partial humerus, and finger bones. The femur has features interpreted as evidence of some bipedal walking, while the curved finger bone suggests that tree climbing remained important.

Its exact position on the human family tree is debated. Some researchers have argued that Orrorin may be closer to modern humans than Australopithecus, whereas other analyses place it among basal hominins without treating it as a direct human ancestor. That uncertainty does not change the identity behind the nickname.