Koobi Fora Formation Research Articles

Ungulate turnover in the Koobi Fora Formation: Spatial and temporal variation in the Early Pleistocene

The Koobi Fora Formation, located east of Lake Turkana in northern Kenya, is well-known for its well-sampled vertebrate fossil record. Thousands of identifiable remains have been collected from three Early Pleistocene geologic members of the Koobi Fora Formation: the Upper Burgi (1.98–1.87 Ma), KBS (1.87–1.56 Ma), and Okote (1.56–1.38 Ma). The large sample from these members permits analysis of spatial and temporal variation in species composition, particularly as it relates to broader changes within the basin. To investigate paleoecological trends in the Koobi Fora Formation during this period, we examine spatial and temporal variation in the proportional abundance of a large sample (NISP = 3713) of ecologically diverse ungulate taxa, in addition to variation in enamel isotope δ13C values. We find that the Karari subregion experienced significant turnover within key large mammalian families (Bovidae, Suidae, and Equidae) during this period, while changes in other subregions (Ileret and Koobi Fora Ridge) were relatively minimal. Our analyses indicate drier conditions in the Karari during the regression of Paleolake Lorenyang as the dominant water-dependent taxa (e.g., the bovid tribe Reduncini and the suid genus Kolpochoerus) were largely replaced with taxa adapted to xeric habitats including the bovid tribe Alcelaphini and the suid genus Metridiochoerus. Little change was detected in proportional abundances of broad dietary groups (grazers: mixed-feeders: browsers). These findings provide a more resolved spatiotemporal resolution for the mammalian communities occupying the region during this time. They further highlight the importance of considering localized habitat differentiation in eastern Africa during the Early Pleistocene, acknowledging that fossil records document complex and dynamic systems which varied spatially and temporally on many scales, much like modern African ecosystems.

Cross-sectional properties of the humeral diaphysis of Paranthropus boisei: Implications for upper limb function

A ∼1.52 Ma adult upper limb skeleton of Paranthropus boisei (KNM-ER 47000) recovered from the Koobi Fora Formation, Kenya (FwJj14E, Area 1A) includes most of the distal half of a right humerus (designated KNM-ER 47000B). Natural transverse fractures through the diaphysis of KNM-ER 470000B provide unobstructed views of cortical bone at two sections typically used for analyzing cross-sectional properties of hominids (i.e., 35% and 50% of humerus length from the distal end). Here we assess cross-sectional properties of KNM-ER 47000B and two other P. boisei humeri (OH 80-10, KNM-ER 739). Cross-sectional properties for P. boisei associated with bending/torsional strength (section moduli) and relative cortical thickness (%CA; percent cortical area) are compared to those reported for nonhuman hominids, AL 288-1 (Australopithecus afarensis), and multiple species of fossil and modern Homo. Polar section moduli (Zp) are assessed relative to a mechanically relevant measure of body size (i.e., the product of mass [M] and humerus length [HL]). At both diaphyseal sections, P. boisei exhibits %CA that is high among extant hominids (both human and nonhuman) and similar to that observed among specimens of Pleistocene Homo. High values for Zp relative to size (M × HL) indicate that P. boisei had humeral bending strength greater than that of modern humans and Neanderthals and similar to that of great apes, A. afarensis, and Homo habilis. Such high humeral strength is consistent with other skeletal features of P. boisei (reviewed here) that suggest routine use of powerful upper limbs for arboreal climbing.

Humeral anatomy of the KNM-ER 47000 upper limb skeleton from Ileret, Kenya: Implications for taxonomic identification

KNM-ER 47000 is a fossil hominin upper limb skeleton from the Koobi Fora Formation, Kenya (FwJj14E, Area 1A) that includes portions of the scapula, humerus, ulna, and hand. Dated to ∼1.52 Ma, the skeleton could potentially belong to one of multiple hominin species that have been documented in the Turkana Basin during this time, including Homo habilis, Homo erectus, and Paranthropus boisei. Although the skeleton lacks associated craniodental material, the partial humerus (described here) preserves anatomical regions (i.e., distal diaphysis, elbow joint) that are informative for taxonomic identification among early Pleistocene hominins. In this study, we analyze distal diaphyseal morphology and the shape of the elbow region to determine whether KNM-ER 47000 can be confidently attributed to a particular species. The morphology of the KNM-ER 47000 humerus (designated KNM-ER 47000B) is compared to that of other early Pleistocene hominin fossil humeri via the application of multivariate ordination techniques to both two-dimensional landmark data (diaphysis) and scale-free linear shape data (elbow). Distance metrics reflecting shape dissimilarity between KNM-ER 47000B and other fossils (and species average shapes) are assessed in the context of intraspecific variation within modern hominid species (Homo sapiens, Pan troglodytes, Gorilla gorilla, Pongo pygmaeus). Our comparative analyses strongly support attribution of KNM-ER 47000 to P. boisei. Compared to four other partial skeletons that have (justifiably or not) been attributed to P. boisei, KNM-ER 47000 provides the most complete picture of upper limb anatomy in a single individual. The taxonomic identification of KNM-ER 47000 makes the skeleton an important resource for testing future hypotheses related to P. boisei upper limb function and the taxonomy of isolated early Pleistocene hominin remains.

Scapular anatomy of Paranthropus boisei from Ileret, Kenya

KNM-ER 47000A is a new 1.52 Ma hominin scapular fossil belonging to an associated partial skeleton from the Koobi Fora Formation, Kenya (FwJj14E, Area 1A). This fossil effectively doubles the record of Early Pleistocene scapulae from East Africa, with KNM-WT 15000 (early African Homo erectus) preserving the only other known scapula to date. KNM-ER 47000A consists of a complete glenoid cavity preserving a portion of the scapular spine and neck, the proximal half of the acromion, and a majority of the axillary border. A sufficient amount of anatomy is preserved to compare KNM-ER 47000A with scapulae of several Australopithecus species, extinct Homo, and living hominoids. The glenohumeral joint of KNM-ER 47000A is more laterally oriented than those of great apes and Australopithecus, aligning it closely with KNM-WT 15000 and modern humans. While this morphology does not imply a strong commitment to arboreality, its scapular spine is obliquely oriented—as in gorillas and some Australopithecus fossils—particularly when compared to the more horizontal orientation seen in KNM-WT 15000 and modern humans. Such a spine orientation suggests a narrow yet long infraspinous region, a feature that has been attributed to suspensory taxa. Accordingly, the morphology of KNM-ER 47000A presents conflicting behavioral implications. Nonetheless, a multivariate consideration of the available scapular traits aligns KNM-ER 47000A and Australopithecus with great apes, whereas KNM-WT 15000 resembles modern humans. The scapular morphology of KNM-ER 47000A is unique among fossil and extant hominoids and its morphological differences from KNM-WT 15000 strengthen the attribution of KNM-ER 47000 to Paranthropus boisei as opposed to early Homo. As the first evidence of scapular morphology in P. boisei, KNM-ER 47000A provides important new information on variation in hominin shoulder and upper limb anatomy from this critical period of hominin evolutionary history.

Crevasse‐splay and associated depositional environments of the hominin‐bearing lower Okote Member, Koobi Fora Formation (Plio‐Pleistocene), Kenya

AbstractThe Okote Member from the northeast Turkana Basin of Kenya represents an exceptionally good archive of Early Pleistocene archaeological and fossil sites. Field study of the lower Okote Member and underlying deposits was conducted in detail at two sets of outcrops (500 to 1000 m long) separated by some 22 km of modern landscape. The examined sections (10 to 15 m thick) preserve two facies: interbedded sandstones, tuffs and mudstones (crevasse splay) and ribbon‐like bodies of sandstone/tuff (crevasse channel). Mudstones are overprinted with small carbonate nodules and sparse slickensides that are interpreted as evidence of weak soil development after the cessation of suspension deposition in a floodplain. The immaturity of the ancient soils implies that sediment accumulation was fairly rapid, yet the nodules and slickensides indicate seasonal contrasts in moisture. Episodically rapid sedimentation is suggested by the types of depositional environments and their structures, and indications of soft‐sediment deformation. Crevassing may have been influenced by rivers that flooded in response to monsoonal rainfall variations and the voluminous influx of fluvially reworked volcaniclastics to the basin. A well‐developed palaeosol directly underlying the lower Okote Member suggests that the deposits accumulated following a significant depositional hiatus. This basal contact, in addition to the apparent pervasiveness and penecontemporaneousness of the sedimentary facies, resembles a crevasse‐splay system deposited by a sub‐delta lobe or river avulsion. A paucity of lacustrine/deltaic indicators might indicate that the studied deposits correspond better with an avulsion origin. Sedimentation rates calculated from prior radiometric dating of tuffs tend to overestimate the timeframe of accumulation for individual strata of the lower Okote Member. Many appear to have formed on the order of 100to 103 years, as suggested by facies, palaeosols and observations of modern crevasse splays. This cautions against using sedimentation rates alone to infer how much time a stratum preserving fossil/archaeological information represents.

Humeral torsion does not dictate shoulder position, but does influence throwing speed

KNM-ER 47000A is a new 1.52 Ma hominin scapular fossil belonging to an associated partial skeleton from the Koobi Fora Formation, Kenya (FwJj14E, Area 1A). This fossil effectively doubles the record of Early Pleistocene scapulae from East Africa, with KNM-WT 15000 (early African Homo erectus) preserving the only other known scapula to date. KNM-ER 47000A consists of a complete glenoid cavity preserving a portion of the scapular spine and neck, the proximal half of the acromion, and a majority of the axillary border. A sufficient amount of anatomy is preserved to compare KNM-ER 47000A with scapulae of several Australopithecus species, extinct Homo, and living hominoids. The glenohumeral joint of KNM-ER 47000A is more laterally oriented than those of great apes and Australopithecus, aligning it closely with KNM-WT 15000 and modern humans. While this morphology does not imply a strong commitment to arboreality, its scapular spine is obliquely oriented—as in gorillas and some Australopithecus fossils—particularly when compared to the more horizontal orientation seen in KNM-WT 15000 and modern humans. Such a spine orientation suggests a narrow yet long infraspinous region, a feature that has been attributed to suspensory taxa. Accordingly, the morphology of KNM-ER 47000A presents conflicting behavioral implications. Nonetheless, a multivariate consideration of the available scapular traits aligns KNM-ER 47000A and Australopithecus with great apes, whereas KNM-WT 15000 resembles modern humans. The scapular morphology of KNM-ER 47000A is unique among fossil and extant hominoids and its morphological differences from KNM-WT 15000 strengthen the attribution of KNM-ER 47000 to Paranthropus boisei as opposed to early Homo. As the first evidence of scapular morphology in P. boisei, KNM-ER 47000A provides important new information on variation in hominin shoulder and upper limb anatomy from this critical period of hominin evolutionary history.

Humeral torsion and throwing proficiency in early human evolution

KNM-ER 47000A is a new 1.52 Ma hominin scapular fossil belonging to an associated partial skeleton from the Koobi Fora Formation, Kenya (FwJj14E, Area 1A). This fossil effectively doubles the record of Early Pleistocene scapulae from East Africa, with KNM-WT 15000 (early African Homo erectus) preserving the only other known scapula to date. KNM-ER 47000A consists of a complete glenoid cavity preserving a portion of the scapular spine and neck, the proximal half of the acromion, and a majority of the axillary border. A sufficient amount of anatomy is preserved to compare KNM-ER 47000A with scapulae of several Australopithecus species, extinct Homo, and living hominoids. The glenohumeral joint of KNM-ER 47000A is more laterally oriented than those of great apes and Australopithecus, aligning it closely with KNM-WT 15000 and modern humans. While this morphology does not imply a strong commitment to arboreality, its scapular spine is obliquely oriented—as in gorillas and some Australopithecus fossils—particularly when compared to the more horizontal orientation seen in KNM-WT 15000 and modern humans. Such a spine orientation suggests a narrow yet long infraspinous region, a feature that has been attributed to suspensory taxa. Accordingly, the morphology of KNM-ER 47000A presents conflicting behavioral implications. Nonetheless, a multivariate consideration of the available scapular traits aligns KNM-ER 47000A and Australopithecus with great apes, whereas KNM-WT 15000 resembles modern humans. The scapular morphology of KNM-ER 47000A is unique among fossil and extant hominoids and its morphological differences from KNM-WT 15000 strengthen the attribution of KNM-ER 47000 to Paranthropus boisei as opposed to early Homo. As the first evidence of scapular morphology in P. boisei, KNM-ER 47000A provides important new information on variation in hominin shoulder and upper limb anatomy from this critical period of hominin evolutionary history.

Feeding habits of extant and fossil canids as determined by their skull geometry

AbstractThe canids belong to one of the most prominent families of mammalian carnivores. Feeding adaptations of extant species is well documented by field observations; however, we are still missing palaeoecological insights for many enigmatic fossil specimens. We employ geometric morphometrics to quantify skull size and shape in extant and fossil members of the Canini tribe, inclusive of jackals and wolf‐like taxa. Skull data are tested to identify correlates of dietary adaptations in extant species for predicting adaptations in fossils. Main vectors of shape variation correlate with the relative skull‐palatal length, the position of the upper carnassial tooth and the anterior tip of the secondary palate. Allometry occurs in the palatal shape but size explains only a small fraction (about 4%) of shape variance. Although we quantified only palatal and tooth shape for the inclusion of fragmentary fossils, discriminant function analysis successfully classify extant Canini in dietary groups (small, medium and large prey specialist) with 89% of accuracy. The discriminant functions provide insights into many enigmatic specimens such as Eucyon adoxus (=small prey), fossil jackal‐like from Koobi Fora formation (=small prey) and the Plio‐Pleistocene Old World canid guild (Canis etruscus, C. arnensis and Lycaon falconeri). Clearly, both skull size and shape are excellent predictors of feeding habits in Canini thus also provide information about fossil taxonomic affinities.

Shell and operculum taphonomy of the bithyniid gastropodGabbiellain the Pleistocene Turkana Basin, North Kenya

Shells and opercula of bithyniid gastropods assigned toGabbiellaare found in high abundance in the Pleistocene upper Burgi and KBS Members of the Koobi Fora Formation, Turkana Basin, northern Kenya. The systematic paleontology of the Turkana BasinGabbiellais revised herein based on morphological comparison with the opercula of other Recent African bithyniids. The fossils from the upper Burgi and KBS Members are here assigned toGabbiella roseaMandahl-Barth, 1968, a species not known from the Turkana fossil record before, but extant in this lake today. A sampling and taphonomic bias is identified which influences the relative abundance ofGabbiellashells and opercula, as a mesh size of 0.63 mm or less is necessary to capture all opercula preserved in the sediments. Accordingly, opercula were found to be significantly more abundant than shells, indicating a different preservation potential of shells and opercula, as the calcitic operculum is more robust than the aragonitic shell. In contrast to previous arguments that most shellbeds in the Turkana Basin sequence represent undisturbed life assemblages, a taphonomic bias is clearly evident reducing the fidelity of the Turkana Basin mollusk assemblages.

A New and Open CoiledValvata(Gastropoda) from the Pliocene Koobi Fora Formation of the Turkana Basin, Northern Kenya

New field collections allow the study and description ofValvata juliaenew species from the Pliocene upper Burgi Member of the Koobi Fora Formation of Kenya. The shell morphology of this species varies from trochospiral to planispiral to open coiled. The species is restricted to a short stratigraphic interval.Valvata juliaeis considered as an invader of the Turkana Basin during a lacustrine transgression event. The open coiling of the species is interpreted as an ecophenotypic response to a high level of environmental stress caused by lake level fluctuations and emergence of delta systems. These environmental conditions broughtValvata juliaeto extinction soon after it invaded the Turkana Basin.

Early hominin diet included diverse terrestrial and aquatic animals 1.95 Ma in East Turkana, Kenya

The manufacture of stone tools and their use to access animal tissues by Pliocene hominins marks the origin of a key adaptation in human evolutionary history. Here we report an in situ archaeological assemblage from the Koobi Fora Formation in northern Kenya that provides a unique combination of faunal remains, some with direct evidence of butchery, and Oldowan artifacts, which are well dated to 1.95 Ma. This site provides the oldest in situ evidence that hominins, predating Homo erectus, enjoyed access to carcasses of terrestrial and aquatic animals that they butchered in a well-watered habitat. It also provides the earliest definitive evidence of the incorporation into the hominin diet of various aquatic animals including turtles, crocodiles, and fish, which are rich sources of specific nutrients needed in human brain growth. The evidence here shows that these critical brain-growth compounds were part of the diets of hominins before the appearance of Homo ergaster/erectus and could have played an important role in the evolution of larger brains in the early history of our lineage.

New species of Crocuta from the early Pliocene of Kenya, with an overview of early Pliocene hyenas of eastern Africa

ABSTRACT A new species of Crocuta (spotted hyenas), Crocuta eturono n. sp., from the Early Pliocene of the Turkana Basin, Kenya is described. The species has been recovered from LO6S, a site in the Kataboi Member of the Nachukui Formation, on the western side of Lake Turkana. The site is dated to >3.4 Ma. The new species differs from all previously identified species of Crocuta in its length proportions of the cheek teeth, having a very long m1 and short p3 and p4. The species is also tentatively identified from the Tulu Bor Member of the Koobi Fora Formation, east side of Lake Turkana. The new species provides information for a discussion of the structure of the hyena guild in eastern Africa 4–3 Ma. Three groups of taxa are identified with distinct distributions. It is hypothesized that specific ecomorphologies of each group account for these distinctions.

Landscape-scale variation in hominin tool use: Evidence from the Developed Oldowan

The relationship between artifact manufacture, use, and discard in the Developed Oldowan is complex. Here we use digital-image-analysis techniques to investigate the intensity of reduction in single-platform cores of the Developed Oldowan of the Okote Member, Koobi Fora Formation. Data suggest that this method provides a more accurate measure of reduction intensity than previous applications of a unifacial-scraper model. Assemblages of single-platform cores excavated from extensive lateral exposures of the Okote Member provide insights into the relationship between raw-material availability and discard patterns. Variation in reduction intensity suggests that tools are not always discarded in patterns that would be predicted by the availability of raw material. Further, it appears that hominin transport decisions involved an assessment of the potential use-life of certain forms. Many aspects of Developed Oldowan technology conform to previously developed models of curated technologies.

Oldowan reduction sequences: methodological considerations

Transport of resources is a major feature of Oldowan hominin technological adaptations. Comparisons between different Oldowan localities often employ measures of transport that are based on artefact attributes as proxies for the intensity of raw material utilization. The Technological Flake Category system [Toth, N., 1985. Oldowan reassessed: a close look at early stone artifacts, Journal of Archaeological Science 12, pp. 101–120] has been used extensively to infer the relative intensity of lithic reduction within Oldowan assemblages. Here we use a large experimental sample to test the relationship between a flake's stage in a reduction sequence and various quantitative attributes. We demonstrate how many previously described attributes are affected by initial core size. We then develop a multiple linear regression model that incorporates several variables to predict the placement of a flake within a generalized reduction sequence. The model is then applied to Oldowan assemblages in the Koobi Fora Formation which explores the strengths and weaknesses of different methods of investigating reduction intensity on an assemblage level.

Plio-Pleistocene facies environments from the KBS Member, Koobi Fora Formation: implications for climate controls on the development of lake-margin hominin habitats in the northeast Turkana Basin (northwest Kenya)

Climate change is hypothesized as a cause of major events of Plio-Pleistocene East African hominin evolution, but the vertically discontinuous and laterally confined nature of the relevant geological records has led to difficulties with assessing probable links between the two. High-resolution sedimentary sequences from lacustrine settings can provide comprehensive data of environmental changes and detailed correlations with well-established orbital and marine records of climate. Hominin-bearing deposits from Koobi Fora Ridge localities in the northeast Turkana Basin of Kenya are an archive of Plio-Pleistocene lake-margin sedimentation though significant developmental junctures of northern African climates, East African environments, and hominin evolution. This study examines alluvial channel and floodplain, nearshore lacustrine, and offshore lacustrine facies environments for the approximately 136-m-thick KBS Member (Koobi Fora Formation) exposed at the Koobi Fora Ridge. Aspects of the facies environments record information on the changing hydrosedimentary dynamics of the lake margin and give insights into potential climatic controls. Seasonal/yearly climate changes are represented by the varve-like laminations in offshore mudstones and the slickensides, dish-shaped fractures, and other paleosol features overprinted on floodplain strata. Vertical shifts between facies environments, however, are interpreted to indicate lake-level fluctuations deriving from longer-term, dry-wet periods in monsoonal rainfall. Recurrence periods for the inferred lake-level changes range from about 10,000 to 50,000 years, and several are consistent with the average estimated timescales of orbital precession (∼20,000 years) and obliquity (∼40,000 years). KBS Member facies environments from the Koobi Fora Ridge document the development of lake-margin hominin habitats in the northeast Turkana Basin. Environmental changes in these habitats may be a result of monsoonal rainfall variations that derive from orbital insolation and/or glacial forcing.

Paleogeographic variations of pedogenic carbonate δ 13C values from Koobi Fora, Kenya: implications for floral compositions of Plio-Pleistocene hominin environments

Plio-Pleistocene East African grassland expansion and faunal macroevolution, including that of our own lineage, are attributed to global climate change. To further understand environmental factors of early hominin evolution, we reconstruct the paleogeographic distribution of vegetation (C 3-C 4 pathways) by stable carbon isotope (δ 13C) analysis of pedogenic carbonates from the Plio-Pleistocene Koobi Fora region, northeast Lake Turkana Basin, Kenya. We analyzed 202 nodules (530 measurements) from ten paleontological/archaeological collecting areas spanning environments over a 50-km 2 area. We compared results across subregions in evolving fluviolacustrine depositional environments in the Koobi Fora Formation from 2.0–1.5 Ma, a stratigraphic interval that temporally brackets grassland ascendancy in East Africa. Significant differences in δ 13C values between subregions are explained by paleogeographic controls on floral composition and distribution. Our results indicate grassland expansion between 2.0 and 1.75 Ma, coincident with major shifts in basin-wide sedimentation and hydrology. Hypotheses may be correct in linking Plio-Pleistocene hominin evolution to environmental changes from global climate; however, based on our results, we interpret complexity from proximate forces that mitigated basin evolution. An ∼2.5 Ma tectonic event in southern Ethiopia and northern Kenya exerted strong effects on paleography in the Turkana Basin from 2.0–1.5 Ma, contributing to the shift from a closed, lacustrine basin to one dominated by open, fluvial conditions. We propose basin transformation decreased residence time for Omo River water and expanded subaerial floodplain landscapes, ultimately leading to reduced proportions of wooded floras and the establishment of habitats suitable for grassland communities.

Implications of new early Homo fossils from Ileret, east of Lake Turkana, Kenya

Sites in eastern Africa have shed light on the emergence and early evolution of the genus Homo. The best known early hominin species, H. habilis and H. erectus, have often been interpreted as time-successive segments of a single anagenetic evolutionary lineage. The case for this was strengthened by the discovery of small early Pleistocene hominin crania from Dmanisi in Georgia that apparently provide evidence of morphological continuity between the two taxa. Here we describe two new cranial fossils from the Koobi Fora Formation, east of Lake Turkana in Kenya, that have bearing on the relationship between species of early Homo. A partial maxilla assigned to H. habilis reliably demonstrates that this species survived until later than previously recognized, making an anagenetic relationship with H. erectus unlikely. The discovery of a particularly small calvaria of H. erectus indicates that this taxon overlapped in size with H. habilis, and may have shown marked sexual dimorphism. The new fossils confirm the distinctiveness of H. habilis and H. erectus, independently of overall cranial size, and suggest that these two early taxa were living broadly sympatrically in the same lake basin for almost half a million years.

Sequence of tuffs between the KBS Tuff and the Chari Tuff in the Turkana Basin, Kenya and Ethiopia

This paper describes a sequence of tuffs between the KBS and the Chari Tuff of Omo Group formations in Kenya and Ethiopia. These tuffs have recently been shown to be 1.87 ± 0.02 Ma and 1.38 ± 0.03 Ma in age, respectively. The sequence of tuffs that is derived is consistent with 40 Ar/ 39 Ar ages reported separately, and provides the stratigraphic framework for interpreting those ages. Further, new correlations are established to the Konso Formation in southern Ethiopia. As drainage from the Ethiopian Rift to the Omo–Turkana Basin developed after deposition of the Konso Formation, pumice clasts in tuffs of the Omo–Turkana Basin probably were transported there by the Omo River. The tuffs are divided into five groups on the basis of their stratigraphic position in relation to extensive ash layers. The sequence of tuffs has import for the placement and age of archaeological sites in the Koobi Fora Formation, and for ages of mammalian faunas (including hominids). Many tuffs were deposited during a 90 ka interval during which Mediterranean sapropels are lacking, suggesting that Nile flow was reduced, and that the level of a lake that occupied the Omo–Turkana Basin at the time was low. Thus the record of climatic influence on deposition in the Omo–Turkana Basin, previously shown for the Kibish Formation (≤200 ka), extends at least to early Pleistocene time.

Early Hominin Activity Traces at FxJj43, a One and a Half Million Year Old Locality in the Koobi Fora Formation, in Northern Kenya: a Field Report

FxJj43 is one of a series of Early Stone Age archaeological sites preserved in the Okote Member of the Koobi Fora Formation, in northern Kenya. It is the focus of a new research project that aims to explore the impact of time-averaging on the composition and characteristics of Early Stone Age archaeological assemblages. FxJj43 lends itself particularly well to this exercise because, unlike other sites in the Okote Member, it preserves a laterally extensive set of interlocking landforms. These include part of a sandy river channel, its southern bank, levee, and adjacent floodplain.Chipped stone artefacts and broken-up animal bones occur in clusters of varying size and density all the way along the 200 m long strip of outcrops containing the remnants of these landforms. Small-scale excavations aimed at investigating the characteristics of archaeological assemblages preserved in different palaeotopographic settings, and in clusters of varying size and density, suggest the existence of archaeological occurrences representing different amounts of overprinting. This underscores the long-term research potential of this locality for exploring the relationship between the material remains of individual behavioural events and agglomerations of debris resulting from many, often unrelated sets of activities.

The Structure of the Lower Pleistocene Archaeological Record: A Case Study From the Koobi Fora Formation [and Comments and Reply

The Structure of the Lower Pleistocene Archaeological Record: A Case Study From the Koobi Fora Formation [and Comments and Reply