Kenyanthropus platyops is an extinct hominin species that inhabited Kenya during the Pliocene epoch, approximately 3.5 to 3.2 million years ago. Its scientific name, Kenyanthropus platyops, translates to “flat-faced man from Kenya,” referencing its origin and a distinctive characteristic of its skull. This species represents a branch of early human relatives, coexisting with other hominin species in East Africa.
The Discovery at Lake Turkana
In 1999, during an expedition led by paleoanthropologist Meave Leakey’s team in the Lake Turkana region of northern Kenya, Justus Erus, a team member, uncovered significant fossil remains. The most notable find was a cranium, designated KNM-WT 40000, leading to the species’ naming.
The cranium was found in a significantly crushed and distorted state, composed of approximately 1,100 pieces. Its reconstruction and analysis were challenging. Despite the damage, the fossil provided new insights into Pliocene hominin diversity in East Africa.
Distinctive Physical Features
The most distinguishing characteristic of Kenyanthropus platyops is its unusually flat, or orthognathic, face. This contrasts sharply with the more projecting, ape-like prognathic face seen in its contemporary, Australopithecus afarensis. The flatness is particularly noticeable across the nasal region and below the nose.
Beyond its flat face, Kenyanthropus platyops also had relatively high cheekbones and smaller molar teeth compared to other hominins of its time. While its brain size was similar to that of Australopithecus afarensis, the combination of a flat face, forward-facing cheekbones, and smaller molars set it apart from other Middle Pliocene hominins.
A Puzzling Place in the Human Family Tree
The unique combination of features in Kenyanthropus platyops puzzles paleoanthropologists regarding its place in the human family tree. One hypothesis suggests its flat face is an advanced trait, potentially linking it more closely to the Homo lineage than to the Australopithecines. This perspective views Kenyanthropus platyops as a possible direct ancestor to later flat-faced hominins like Homo rudolfensis, despite a 1.5-million-year time gap.
An opposing hypothesis argues that the crushed and distorted condition of the KNM-WT 40000 skull makes definitive classification difficult. Some experts propose that the “flatness” might be an artifact of this damage, suggesting that Kenyanthropus platyops could simply be a regional variant of Australopithecus afarensis. Alternatively, it might represent a separate, parallel branch of hominin evolution that ultimately went extinct without contributing to the modern human lineage. Its exact position in the human family tree remains an unresolved subject of ongoing scientific debate due to the limited and damaged fossil evidence.
Life in the Pliocene Epoch
Kenyanthropus platyops inhabited the Lake Turkana region in Kenya during the Pliocene, a landscape of woodlands and grasslands. This environment offered diverse resources. Faunal evidence suggests its habitat was wetter and more closed than environments linked to Australopithecus afarensis at sites like Hadar.
Based on its relatively small molar teeth, Kenyanthropus platyops likely ate softer plant foods, such as fruits, leaves, and roots. This diet differed from hominins adapted to tougher materials, allowing species to coexist by foraging for distinct items. Kenyanthropus platyops was not alone; it shared its environment with other hominin species, including Australopithecus afarensis, illustrating the complex, multi-branched nature of human evolution during this period.