Paleontology and Biochronology of Fossil Localities in the Manonga Valley, Tanzania

Comparisons of the Manonga Valley faunas with those from other East African localities for which radiometric dates have been obtained allow the Manonga Valley sequence to be placed within a broader chronological framework. The results of a biochronological analysis produce consistent estimates of the age range of the sequence, and indicate that the fossiliferous sediments were laid down during the late Miocene and early Pliocene. Nevertheless, it should be noted that there are several constraining factors that limit the degree of precision of such correlations, as follows: (1) There are few late Miocene and early Pliocene sites that have been dated radiometrically, and these are restricted geographically to the East African Rift valley (i.e., the Turkana basin, the Baringo basin, the Samburu Hills, and the Middle Awash Valley); (2) with the exception of Lotha-gam in northern Kenya and Langebaanweg in South Africa, the mammalian faunas from this time period are either poorly known or have not been the subject of detailed study; and (3) few researchers have made detailed firsthand comparisons between late Miocene and early Pliocene faunas from fossil localities in North, East, and South Africa.