Temporal and Stratigraphic Framework for Paleoanthropology Sites Within East-Central Area 130, Koobi Fora, Kenya

Abstract

In the Koobi Fora region of the northeast Lake Turkana Basin (Kenya) dozens of archeological sites have been studied for decades in order to understand the behavior of Early Pleistocene hominins. Data collected from these sites have been important for demonstrating the manufacture styles of Oldowan stone-tool users, hominin dietary preferences, and processes of Early Stone Age site formation. A particularly rich locality is collection Area 130. Area 130 is noteworthy for hominin fossils KNM-ER 1805 (Homo) and 1806 (Paranthropus) as well as the FxJj 18 site complex, which represents one of the type localities for the Developed Oldowan of Koobi Fora. However, despite research beginning in the late 1960s, and several revisions to the stratigraphy and dating of the Koobi Fora Formation, few published studies provide a detailed chronostratigraphy for Area 130. The lack of a detailed chronostratigraphy has contributed to conflicting interpretations for the dates of the hominin fossils and archaeological sites. Here we present new geochronologic and paleomagnetic data to develop a chronostratigraphic framework that allows us to directly assess the age of the sediments, fossils, and artifacts from Area 130. Individual pumices from the Orange Tuff marker level and a previously unnamed tuff exposed near the FxJj 18 archaeological site complex (referred here as the FxJj 18 tuff) were analyzed for high-precision single crystal 40 Ar/ 39 Ar dating and dated at 1.763 ± 0.007 Ma and 1.520 ± 0.005 Ma respectively. Concurrently, we collected orientated paleomagnetic samples from stratigraphic levels of the KBS Member in Area 130 and used them to develop a magnetostratigraphic section. Our findings can be used to refine the sequence and chronology of the archaeological and fossils sites from Area 130 and other penecontemporaneous sites within the Lake Turkana Basin. Our data show that the first appearance of the Developed Oldowan for Koobi Fora does not correlate with any obvious evolutionary changes represented by the local hominin hypodigm nor with the arrival of a cognitively advanced hominin. Therefore we speculate that the advent of this more sophisticated type of stone tool was a response to a change in the diet of the genus Homo.

Beyond the genus stereotype. Who were the first toolmarkers in Africa? Crossed views between archaeology and anatomy

“…Forty metres east of these paleoanthropological localities, on the same stratigraphical horizon, lies the archaeological site FxJj 38 North West. The composition of the lithic assemblage, with a large chopper component, is consistent with that of Olduvai Bed I and therefore allocated to the Oldowan (Harris & Herbich, 1978) and represents one of the type localities for the Developed Oldowan of Koobi Fora (Mana et al, 2019). These hominin remains and archaeological site belong to the KBS Member, below the base of the Okote Member and above the KBS Tuff.…”

“…These sites are, according to Mana and co-authors, broadly constrained between 1.78 and 1.52 Ma (Mana et al, 2019). This is in contradiction with the interpretation of Feibel and collaborators who estimated its age at 1.85 Ma (Feibel et al, 1989).…”

Contracting eastern African C4 grasslands during the extinction of Paranthropus boisei

“…Similar biogeographic distributions and habitat preferences of members of Homo and P. boisei 62 implies competition for non-food resources including but not limited to feeding territories, sleeping sites, and potable water. Evidence for the origins 5 , 64 and evolution 65 , 66 of Early Stone Age technologies has shifted the discussion of presence vs. absence of tool making abilities by P. boisei and other non- Homo hominin species further toward the cognitive and social learning capacities required for habitual and advanced stone tool making 67 . The large-brained and -bodied H. erectus remains the most likely maker of advanced tools during the MPT interval 62 and may have outcompeted P. boisei for non-food resources and some C 4 plant foods with those tools.…”

Influences of dietary niche expansion and Pliocene environmental changes on the origins of stone tool making

“…Sediments capture several key evolutionary landmarks in the hominin lineage including the first appearance datum (FAD) of genus Australopithecus (Leakey et al 1995), FAD and the last appearance datum (LAD) of K. platyops (Leakey et al, 2001), an early Homo sp. candidate FAD (Prat et al, 2005), H. rudolfensis FAD (Leakey, 1973), H. habilis FAD and LAD (Spoor et al, 2007;Wood, 1991), the earliest Acheulean industry (Lepre et al, 2011), numerous Pleistocene sites preserving Oldowan industry diversity through time (Braun et al, 2010;Delagnes and Roche, 2005;Isaac, 1997;Harmand, 2007Harmand, , 2009aMana et al, 2019;Roche et al, 1999Roche et al, , 2003, and the focus of this study, the earliest lithic technology, known as the Lomekwian (Harmand et al, 2015).…”