Nariokotome is located on the west side of Lake Turkana in northern Kenya. The most important hominin yielding site, formally known as Nariokotome (NK) III, lies on the south bank of the Nariokotome River, which runs from the Murua Rith mountain range in West Turkana before emptying into the lake. Along its path, the river and its tributaries cut through the strata exposing alternating layers of fluvial and lacustrine sediments intercalated with volcanic ash.

The sediments at Nariokotome, which date to the Plio-Pleistocene, comprise the Nachukui Formation. Like the Koobi Fora Formation, Nachukui is divided into eight members which are each named for their tuffaceous marker bed.

In 1984, the most complete hominin skeleton to date, KNM-WT 15000, was discovered eroding from a hillside at NK III. The specimen, which retained the skull and almost entire postcranial skeleton, belonged to a juvenile male Homo ergaster. Nicknamed the “Turkana Boy,” the specimen was determined to be between 1.51 and 1.56 million years old based upon K/Ar, Ar/Ar and correlations with isotopically dated ashes containing pumice clasts and alkali feldspar. The Turkana Boy has augmented our knowledge on unassociated postcranial bones, growth patterns, and has allowed for brain and body size to be measured on the same individual for the first time.

Interestingly, NK III is not a particularly fossiliferous site. Other than the Turkana Boy, not much else has been discovered there. Additional fossil taxa include the freshwater stingray, Dasyatis Africana; the catfish, Synodontis; the extinct pig, Metrodiocherus; two extinct species of hippopotamus, Hippopotamus gorgops and H. aethiopicus; chelonian carapaces (turtle shells); some avian limb bones and phalanges; two species of bovid; sponge spicules; several species of ostracod (a crustacean); cichlids (a family of perciform fish); cyprinids (carps and minnows); and several varanids (monitor lizards). Additional surface finds have been made in the areas surrounding NK III. The most significant of these findings is KNM-WT 16001, cranial fragments of Homo erectus.

The paleoenvironment of the Nariokotome region during the time of the Turkana Boy has been reconstructed as a temporary marshland formed by the annual flooding of the Omo River with interspersed grassland and patches of woodland. One or more lakes were probably present as well. The absence of large, open water fish suggests that these lakes were most likely shallow. The absence of large meandering channels suggests that large forest habitats were unlikely. Instead, small tributaries of the Omo River were bordered by narrow tracts of trees with gallery forests along the main tributaries. The low diversity in the faunal assemblage at Nariokotome suggests waters with concentrated or inconsistent levels of saline. However, these waters were most likely well oxygenated as evidenced by the large number of ostracods.

References

Brown F, Harris J, Leakey R, Walker A. 1985. Early Homo erectus from west Lake Turkana, Kenya. Nature 316:788-792.

Brown FH, McDougall I. 1993. Geologic setting and age. In The Nariokotome Homo erectus Skeleton, eds. R Leakey and A Walker, pp. 9-20. Cambridge: Harvard University Press.

Feibel CS, Brown FH. 1993. Microstratigraphy and paleoenvironments. In The Nariokotome Homo erectus Skeleton, eds. R Leakey and A Walker, pp. 9-20. Cambridge: Harvard University Press.

Harris JM, Brown FH, Leakey MG. 1988. Geology and paleontology of Plio-Pleistocene localities west of Lake Turkana, Kenya. Contributions in Science 399:1-128.

Walker A. 1993. Taphonomy. In The Nariokotome Homo erectus Skeleton, eds. R Leakey and A Walker, pp. 9-20. Cambridge: Harvard University Press.