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''Kenyanthropus'' is a genus of extinct hominin identified from the
Lomekwi Lomekwi is an archaeological site located on the west bank of Turkana Lake in Kenya. It is an important milestone in the history of human archaeology. An archaeological team from Stony Brook University in the United States discovered traces o ...
site by
Lake Turkana Lake Turkana () is a saline lake in the Kenyan Rift Valley, in northern Kenya, with its far northern end crossing into Ethiopia. It is the world's largest permanent desert lake and the world's largest alkaline lake. By volume it is the world ...
, Kenya, dated to 3.3 to 3.2 million years ago during the Middle Pliocene. It contains one species, ''K. platyops'', but may also include the 2 million year old ''
Homo rudolfensis ''Homo rudolfensis'' is an extinct species of archaic human from the Early Pleistocene of East Africa about 2 million years ago (mya). Because ''H. rudolfensis'' coexisted with several other hominins, it is debated what specimens can be confiden ...
'', or ''K. rudolfensis''. Before its naming in 2001, ''
Australopithecus afarensis ''Australopithecus afarensis'' is an extinct species of australopithecine which lived from about 3.9–2.9 million years ago (mya) in the Pliocene of East Africa. The first fossils were discovered in the 1930s, but major fossil finds would not ta ...
'' was widely regarded as the only australopithecine to exist during the Middle Pliocene, but ''Kenyanthropus'' evinces a greater diversity than once acknowledged. ''Kenyanthropus'' is most recognisable by an unusually flat face and small teeth for such an early
hominin The Hominini (hominins) form a taxonomic tribe of the subfamily Homininae (hominines). They comprise two extant genera: ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos), and in standard usage exclude the genus '' Gorilla'' ( gorillas) ...
, with values on the extremes or beyond the range of variation for australopithecines in regard to these features. Multiple australopithecine species may have coexisted by foraging for different food items (
niche partitioning In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for e ...
), which may be reason why these apes anatomically differ in features related to chewing. The Lomekwi site also yielded the earliest
stone tool Stone tools have been used throughout human history but are most closely associated with prehistoric cultures and in particular those of the Stone Age. Stone tools may be made of either ground stone or knapped stone, the latter fashioned by a ...
industry Industry may refer to: Economics * Industry (economics), a generally categorized branch of economic activity * Industry (manufacturing), a specific branch of economic activity, typically in factories with machinery * The wider industrial sector ...
, the Lomekwian, characterised by the rudimentary production of simple flakes by pounding a
core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (laboratory), a highly specialized shared research resource * Core (manufacturing), used in casting and molding * Core (optical fiber ...
against an anvil or with a
hammerstone In archaeology, a hammerstone is a hard cobble used to strike off lithic flakes from a lump of tool stone during the process of lithic reduction. The hammerstone is a rather universal stone tool which appeared early in most regions of the wo ...
. It may have been manufactured by ''Kenyanthropus'', but it is unclear if multiple species were present at the site or not. The knappers were using volcanic rocks collected no more than from the site. ''Kenyanthropus'' seems to have lived on a lakeside or
floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high Discharge (hydrolog ...
environment featuring forests and grasslands.


Taxonomy


Discovery

In August 1998, field technician Blasto Onyango discovered a
hominin The Hominini (hominins) form a taxonomic tribe of the subfamily Homininae (hominines). They comprise two extant genera: ''Homo'' (humans) and '' Pan'' (chimpanzees and bonobos), and in standard usage exclude the genus '' Gorilla'' ( gorillas) ...
partial left
maxilla In vertebrates, the maxilla (: maxillae ) is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The two maxil ...
(upper jaw), specimen KNM-WT 38350, on the Kenyan
Lomekwi Lomekwi is an archaeological site located on the west bank of Turkana Lake in Kenya. It is an important milestone in the history of human archaeology. An archaeological team from Stony Brook University in the United States discovered traces o ...
dig site by
Lake Turkana Lake Turkana () is a saline lake in the Kenyan Rift Valley, in northern Kenya, with its far northern end crossing into Ethiopia. It is the world's largest permanent desert lake and the world's largest alkaline lake. By volume it is the world ...
, overseen by prominent paleoanthropologists Louise and Meave Leakey. In August 1999 at the Lomekwi site, research assistant Justus Erus discovered an uncharacteristically flat-faced
australopithecine The australopithecines (), formally Australopithecina or Hominina, are generally any species in the related genera of ''Australopithecus'' and ''Paranthropus''. It may also include members of '' Kenyanthropus'', ''Ardipithecus'', and '' Praeant ...
skull, specimen KNM-WT 40000. The 1998–1999 field season subsequently uncovered 34 more craniodental hominin specimens, but the research team was unable to determine if these can be placed into the same species as the former two specimens (that is, if multiple species were present at the site).


Age

The specimens were recovered near the Nabetili tributary of the Lomekwi river in a
mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from ''shale'' by its lack of fissility.Blatt, H., and R.J. Tracy, 1996, ''Petrology.'' New York, New York, ...
layer of the Nachukui Formation. KNM-WT 40000 was recovered from the Kataboi Member, below the 3.4 million year old Tulu Bor
Tuff Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock co ...
, and above the 3.57 million year old Lokochot Tuff. By
linear interpolation In mathematics, linear interpolation is a method of curve fitting using linear polynomials to construct new data points within the range of a discrete set of known data points. Linear interpolation between two known points If the two known po ...
, KNM-WT 40000 is approximately 3.5 million years old, dating back to the Middle Pliocene. Only three more specimens were recovered from the Kataboi Member at around the same level, the deepest KNM-WT 38341 probably sitting on 3.53 million year old sediments. KNM-WT 38350 was recovered from the Lomekwi Member above Tulu Bor, and is approximately 3.3 million years old. The other specimens from this member sit above Tulu Bor, roughly 3.3 million years old as well. The highest specimens—KNM-WT 38344, -55, and -56—may be around 3.2 million years old.


Classification

In 2001, Meave Leakey and colleagues assigned the Lomekwi remains to a new genus and species, ''Kenyanthropus platyops'', with KNM-WT 40000 the
holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...
, and KNM-WT 38350 a
paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype (biology), isotype ...
. The genus name honours Kenya where Lomekwi and a slew of other major human-ancestor sites have been identified. The species name derives from
Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
''platus'' "flat" and ''opsis'' "face" in reference to the unusually flat face for such an early hominin. The classification of early hominins with their widely varying anatomy has been a difficult subject matter. The 20th century generated an overabundance of hominin genera plunging the field into taxonomic turmoil, until German evolutionary biologist
Ernst Mayr Ernst Walter Mayr ( ; ; 5 July 1904 – 3 February 2005) was a German-American evolutionary biologist. He was also a renowned Taxonomy (biology), taxonomist, tropical explorer, ornithologist, Philosophy of biology, philosopher of biology, and ...
, surveying a "bewildering diversity of names", decided to recognise only a single genus, ''Homo'', containing a few species. Though other genera and species have since become popular, his more conservative view of hominin diversity has become the mainstay, and the acceptance of further genera is usually met with great resistance. Since Mayr, hominins are classified into ''
Australopithecus ''Australopithecus'' (, ; or (, ) is a genus of early hominins that existed in Africa during the Pliocene and Early Pleistocene. The genera ''Homo'' (which includes modern humans), ''Paranthropus'', and ''Kenyanthropus'' evolved from some ''Aus ...
'' which gave rise to ''
Homo ''Homo'' () is a genus of great ape (family Hominidae) that emerged from the genus ''Australopithecus'' and encompasses only a single extant species, ''Homo sapiens'' (modern humans), along with a number of extinct species (collectively called ...
'' (which includes modern humans) and the robust ''
Paranthropus ''Paranthropus'' is a genus of extinct hominin which contains two widely accepted species: ''Paranthropus robustus, P. robustus'' and ''P. boisei''. However, the validity of ''Paranthropus'' is contested, and it is sometimes considered to be sy ...
'' (which is sometimes not recognised as its own genus), which by definition leaves ''Australopithecus''
polyphyletic A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...
(a non-natural group which does not comprise a common ancestor and all of its descendants). In addition to ''Kenyanthropus'', the 1990s saw the introduction of '' A. bahrelghazali'', ''
Ardipithecus ''Ardipithecus'' is a genus of an extinct hominine that lived during the Late Miocene and Early Pliocene epochs in the Afar Depression, Ethiopia. Originally described as one of the earliest ancestors of humans after they diverged from the chim ...
'', ''
Orrorin ''Orrorin'' is an extinct genus of primate within Homininae from the Miocene Lukeino Formation and Pliocene Mabaget Formation, both of Kenya. The type species is ''O. tugenenesis'', named in 2001, and a second species, ''O. praegens'', assigne ...
'', and ''
Sahelanthropus ''Sahelanthropus'' is an extinct genus of hominid dated to about during the Late Miocene. The type species, ''Sahelanthropus tchadensis'', was first announced in 2002, based mainly on a partial cranium, nicknamed ''Toumaï'', discovered in north ...
'', which has complicated discussions of hominin diversity, though the latter three have not been met with much resistance on account of their greater age (all predating ''Australopithecus''). At the time ''Kenyanthropus'' was discovered, ''
Australopithecus afarensis ''Australopithecus afarensis'' is an extinct species of australopithecine which lived from about 3.9–2.9 million years ago (mya) in the Pliocene of East Africa. The first fossils were discovered in the 1930s, but major fossil finds would not ta ...
'' was the only recognised australopithecine to have existed between 4 and 3 million years ago, aside from its probable ancestor '' A. anamensis'', making ''A. afarensis'' the likely progenitor of all other australopithecines as they diversified in the late Pliocene and into the
Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
. Leakey and colleagues considered ''Kenyanthropus'' to be evidence of a greater diversity of Pliocene australopithecines than previously acknowledged. In 2015, Ethiopian palaeoanthropologist
Yohannes Haile-Selassie Yohannes Haile-Selassie Ambaye (born 23 February 1961) is an Ethiopian Paleoanthropology, paleoanthropologist. An authority on pre-''Homo sapiens'' hominids, he particularly focuses his attention on the East African Rift and Middle Awash valleys. ...
and colleagues erected a new species, '' A. deyiremeda'', which lived in the same time and region as ''Kenyanthropus'' and ''A. afarensis''. Meave Leakey and colleagues drew attention to namely the flat face and small
cheek teeth Cheek teeth or postcanines comprise the molar and premolar teeth in mammals. Cheek teeth are multicuspidate (having many folds or tubercles). Mammals have multicuspidate molars (three in placentals, four in marsupials, in each jaw quadrant) and ...
, in addition to several other traits, to distinguish the genus from earlier ''
Ardipithecus ''Ardipithecus'' is a genus of an extinct hominine that lived during the Late Miocene and Early Pliocene epochs in the Afar Depression, Ethiopia. Originally described as one of the earliest ancestors of humans after they diverged from the chim ...
'', contemporary and later ''
Australopithecus ''Australopithecus'' (, ; or (, ) is a genus of early hominins that existed in Africa during the Pliocene and Early Pleistocene. The genera ''Homo'' (which includes modern humans), ''Paranthropus'', and ''Kenyanthropus'' evolved from some ''Aus ...
'', and later ''Paranthropus''. ''Kenyanthropus'' lacks any of the derived traits seen in ''Homo''. They conceded ''Kenyanthropus'' could be subsumed into ''Australopithecus'' if the widest definition of the latter is used, but this conservative approach to hominin diversity leaves ''Australopithecus'' a grade taxon, a non-natural grouping of similar-looking species whereby it effectively encompasses all hominins not classifiable into ''Ardipithecus'' or ''Homo'' regardless of how they may be related to each other. Leakey and colleagues further drew parallels with KNM-WT 40000 and the 2 million year old KNM-ER 1470 assigned to ''
Homo rudolfensis ''Homo rudolfensis'' is an extinct species of archaic human from the Early Pleistocene of East Africa about 2 million years ago (mya). Because ''H. rudolfensis'' coexisted with several other hominins, it is debated what specimens can be confiden ...
'', attributing differences in
braincase In human anatomy, the neurocranium, also known as the braincase, brainpan, brain-pan, or brainbox, is the upper and back part of the skull, which forms a protective case around the brain. In the human skull, the neurocranium includes the calv ...
and
nasal Nasal is an adjective referring to the nose, part of human or animal anatomy. It may also be shorthand for the following uses in combination: * With reference to the human nose: ** Nasal administration, a method of pharmaceutical drug delivery * ...
anatomy to archaicness. They suggested ''H. rudolfensis'' may be better classified as ''K. rudolfensis''. In 2003, American palaeoanthropologist Tim D. White was concerned that KNM-WT 40000 was far too distorted to obtain any accurate metrics for classification purposes, especially because the skull was splintered into over 1,100 pieces often measuring less than across. Because such damage is rarely even seen, he argues that it cannot be reliably reconstructed. Because the skulls of modern ape species vary widely, he suggested further fossil discoveries in the region may prove the Lomekwi hominins to be a local variant of ''A. afarensis'' rather than a distinct genus or species. In response, anthropologist Fred Spoor and Meave and Louise Leakey produced much more detailed digital
topographical Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the landforms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary scienc ...
scans of the KNM-WT 40000 maxilla in 2010, permitting the comparison of many more anatomical landmarks on the maxillae of all other early hominins, modern humans,
chimpanzee The chimpanzee (; ''Pan troglodytes''), also simply known as the chimp, is a species of Hominidae, great ape native to the forests and savannahs of tropical Africa. It has four confirmed subspecies and a fifth proposed one. When its close rel ...
s, and
gorilla Gorillas are primarily herbivorous, terrestrial great apes that inhabit the tropical forests of equatorial Africa. The genus ''Gorilla'' is divided into two species: the eastern gorilla and the western gorilla, and either four or five su ...
s, in order to more accurately correct the distortion. The new reconstruction more convincingly verifies the distinctness of ''Kenyanthropus''. In 2003, Spanish writer
Camilo José Cela Conde Camilo José Arcadio Cela Conde, 2nd Marquess of Iria Flavia (born 17 January 1946), is a Spanish writer. He is the son of Nobel Prize in Literature, Nobel Prize winning writer Camilo José Cela and is currently a Professor (highest academic ran ...
and evolutionary biologist
Francisco J. Ayala Francisco José Ayala Pereda (March 12, 1934 – March 3, 2023) was a Spanish-American evolutionary biologist and philosopher who was a longtime faculty member at the University of California, Irvine, and University of California, Davis. Ayal ...
proposed resurrecting the genus "''Praeanthropus''" to house all australopithecines which are not ''Ardipithecus'', ''Paranthropus'', or '' A. africanus'', though they opted to synonymise ''Kenyanthropus'' with ''Homo'' as "''H. platyops''". Their recommendations have been largely rejected.


Anatomy

KNM-WT 40000 has been heavily distorted during the fossilisation process, the braincase shifted downwards and backwards, the nasal region to the right, and the mouth and cheek region forward. It is unclear if the specimen represents a male or a female. ''Kenyanthropus'' has a relatively flat face, including subnasally, between the nose and the mouth (the nasoalveolar clivus). The clivus inclines at 45° (there is relaxed sub-nasal
prognathism Prognathism is a positional relationship of the mandible or maxilla to the skeletal base where either of the jaws protrudes beyond a predetermined imaginary line in the coronal plane of the skull. In the case of ''mandibular'' prognathism (nev ...
), steeper than almost all other australopithecine specimens (on the upper end of variation for ''Paranthropus''), more comparable to ''H. rudolfensis'' and '' H. habilis''. This is the earliest example of a flat face in the hominin fossil record. Unlike ''A. afarensis'', ''Kenyanthropus'' lacks the anterior pillars, bony columns running down from the nasal aperture (nose hole). It is also one of the longest early hominin clivi discovered at . The nasal aperture (nose hole) is narrow compared to that of ''Australopithecus'' and ''Paranthropus''. The cheekbones are tall and steep, and the
anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
surface (where the cheeks juts out the most) is positioned above the premolars, more frequently seen in ''Paranthropus'' than other hominins. The zygomaticoalveolar crest (stretching between the cheek and the teeth) is low and curved. Overall, the face resembles ''H. rudolfensis'', though has longer nasal bones, a narrower nasal aperture, a shorter postcanine (the
molars The molars or molar teeth are large, flat tooth, teeth at the back of the mouth. They are more developed in mammal, mammals. They are used primarily to comminution, grind food during mastication, chewing. The name ''molar'' derives from Latin, '' ...
and
premolar The premolars, also called premolar Tooth (human), teeth, or bicuspids, are transitional teeth located between the Canine tooth, canine and Molar (tooth), molar teeth. In humans, there are two premolars per dental terminology#Quadrant, quadrant in ...
s) tooth row, and a less steeply inclined (less flat, more prognathic) midfacial region. Much later ''Paranthropus'' are also characterised by relatively flat faces, but this is generally considered to be an adaptation to maximise bite force through enormous teeth, which ''Kenyanthropus'' enigmatically does not have. Among all the specimens, only the M2 (2nd upper left molar) and the tooth sockets of the left side of the mouth of KNM-WT 40000 are preserved well enough to measure and study. With dimensions of , a surface area of , it is the smallest M2 ever discovered for an early hominin. For comparison, those of ''A. afarensis'' in the comparative sample Leakey and colleagues used ranged from about , ''H. habilis'' and ''H. rudolfensis'' , and the robust ''P. boisei'' (with the largest molars among hominins) about . The reconstructed dimensions of KNM-WT 38350's M1 are for a surface area of , which is on the lower end of variation for ''A. anamensis'', ''A. afarensis'' and ''H. habilis''. The thick molar enamel is on par with that of ''A. anamensis'' and ''A. afarensis''. KNM-WT40000 retains the ancestral ape premolar tooth root morphology, with a single lingual
root In vascular plants, the roots are the plant organ, organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often bel ...
(on the tongue side) and two buccal roots (towards the cheeks), though the P4 of KNM-WT 38350 may only have a single buccal root; the ancestral pattern is frequent in ''Paranthropus'' and variable in ''Australopithecus''. Individuals of more derived species typically have single-rooted premolars. The canine jugum is not visible (a line of bone in the maxilla corresponding to the canine tooth root), which may mean the canines were not that large. The cross-sectional area of the I2 (2nd upper
incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, wher ...
) is 90% the size of that of I1, whereas it is usually 50 to 70% in other great apes. The tooth roots of the incisors do not appear to be orientated out (there was probably no alveolar prognathism, the front teeth did not jut forward). Brain volume is uncalculable due to distortion of the braincase, but it was probably similar to that of ''Australopithecus'' and ''Paranthropus''. A sample of five ''A. afarensis'' averaged 445 cc. Like ''Paranthropus'', there is no frontal trigon (a triangle formed by the conjunction of the temporal lines behind the brow ridge). Unlike ''H. habilis'' but like ''H. rudolfensis'', there is no sulcus (trench) behind the brow ridge. The degree of postorbital constriction, the narrowing of the braincase in the
frontal lobe The frontal lobe is the largest of the four major lobes of the brain in mammals, and is located at the front of each cerebral hemisphere (in front of the parietal lobe and the temporal lobe). It is parted from the parietal lobe by a Sulcus (neur ...
region, is on par with that of ''Australopithecus'', ''H. rudolfensis'', and ''H. habilis'', but less than '' P. boisei''. Like the earlier '' A. anamensis'' and '' Ar. ramidus'', the
tympanic bone The tympanic part of the temporal bone is a curved plate of bone lying below the squamous part of the temporal bone, in front of the mastoid process, and surrounding the external part of the ear canal. It originates as a separate bone (tympanic ...
retains the ancestral hominin ear morphology, lacking the petrous crest, and bearing a narrow
ear canal The ear canal (external acoustic meatus, external auditory meatus, EAM) is a pathway running from the outer ear to the middle ear. The adult human ear canal extends from the auricle to the eardrum and is about in length and in diameter. S ...
with a small opening. The
foramen magnum The foramen magnum () is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblongata, passes thro ...
, where the skull connects to the
spine Spine or spinal may refer to: Science Biology * Spinal column, also known as the backbone * Dendritic spine, a small membranous protrusion from a neuron's dendrite * Thorns, spines, and prickles, needle-like structures in plants * Spine (zoology), ...
, was probably oval shaped as opposed to the heart-shaped one of ''P. boisei''.


Technology

In 2015, French archaeologist
Sonia Harmand Sonia Harmand (born in 1974) is a French archaeologist who studies Early Stone Age archaeology and the evolution of stone tool making. She received her undergraduate degree from the University of Paris where she was associated with the "Prehistory ...
and colleagues identified the Lomekwian stone-tool
industry Industry may refer to: Economics * Industry (economics), a generally categorized branch of economic activity * Industry (manufacturing), a specific branch of economic activity, typically in factories with machinery * The wider industrial sector ...
at the Lomekwi site. The tools are attributed to ''Kenyanthropus'' as it is the only hominin identified at the site, but in 2015, anthropologist Fred Spoor suggested that at least some of the indeterminate specimens may be assignable to ''A. deyiremeda'' as the two species have somewhat similar maxillary anatomy. At 3.3 million years old, it is the oldest proposed industry. The assemblage comprises 83 cores, 35 flakes, 7 possible anvils, 7 possible
hammerstone In archaeology, a hammerstone is a hard cobble used to strike off lithic flakes from a lump of tool stone during the process of lithic reduction. The hammerstone is a rather universal stone tool which appeared early in most regions of the wo ...
s, 5 pebbles (which may have also been used as hammers), and 12 indeterminant fragments, of which 52 were sourced from
basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...
, 51 from
phonolite Phonolite is an uncommon shallow intrusive or extrusive rock, of intermediate chemical composition between felsic and mafic, with texture ranging from aphanitic (fine-grained) to porphyritic (mixed fine- and coarse-grained). Phonolite is a var ...
, 35 from trachyphonolite (intermediate composition of phonolite and
trachyte Trachyte () is an extrusive igneous rock composed mostly of alkali feldspar. It is usually light-colored and aphanite, aphanitic (fine-grained), with minor amounts of mafic minerals, and is formed by the rapid cooling of lava (or shallow intrus ...
), 3 from vesicular basalt, 2 from trachyte, and 6 indeterminant. These materials could have originated at a conglomerate only from the site. The cores are large and heavy, averaging and . Flakes ranged in length, normally shorter than later
Oldowan The Oldowan (or Mode I) was a widespread stone tool archaeological industry during the early Lower Paleolithic spanning the late Pliocene and the first half of the Early Pleistocene. These early tools were simple, usually made by chipping one ...
industry flakes. Anvils were heavy, up to . Flakes seem to have been cleaved off primarily using the passive hammer technique (directly striking the core on the anvil) and/or the bipolar method (placing the core on the anvil and striking it with a hammerstone). They produced both
uniface In archaeology, a uniface is a specific type of stone tool that has been flaked on one surface only. There are two general classes of uniface tools: modified flakes and formalized tools, which display deliberate, systematic modification of the margi ...
s (the flake was worked on one side) and
biface A hand axe (or handaxe or Acheulean hand axe) is a Prehistory, prehistoric stone tool with two faces that is the longest-used tool in human history. It is made from stone, usually flint or chert that has been "reduced" and shaped from a larger ...
s (both sides were worked). Though they may have been shaping cores beforehand to make them easier to work, the knappers more often than not poorly executed the technique, producing incomplete fractures and fissures on several cores, or requiring multiple blows to flake off a piece. Harmand and colleagues suggested such rudimentary skills may place the Lomekwian as an intermediate industry between simple pounding techniques probably used by earlier hominins, and the flaking Oldowan industry developed by ''Homo''. It is typically assumed that early hominins were using stone tools to cut meat in addition to other organic materials. Wild chimpanzees and black-striped capuchins have been observed to make flakes by accident while using hammerstones to crack nuts on anvils, but the Lomekwi knappers were producing multiple flakes from the same core, and flipped over flakes to work the other side, which speak to the intentionality of their production. In 2016, Spanish archaeologists Manuel Domínguez-Rodrigo and Luis Alcalá argued Harmand and colleagues did not convincingly justify that the tools were discovered ''
in situ is a Latin phrase meaning 'in place' or 'on site', derived from ' ('in') and ' ( ablative of ''situs'', ). The term typically refers to the examination or occurrence of a process within its original context, without relocation. The term is use ...
'', that is, the tools may be much younger and were reworked into an older layer. If the date of 3.3 million years is accepted, then there is a 700,000 year gap between the next solid evidence of stone tools, at Ledi-Geraru associated with the earliest ''Homo''
LD 350-1 LD 350-1 is the earliest known specimen of the genus ''Homo'', dating to 2.75–2.8 million years ago (mya), found in the Ledi-Geraru site in the Afar Region of Ethiopia. The specimen was discovered in silts above the Gurumaha Tuff section of the ...
, the
Oldowan The Oldowan (or Mode I) was a widespread stone tool archaeological industry during the early Lower Paleolithic spanning the late Pliocene and the first half of the Early Pleistocene. These early tools were simple, usually made by chipping one ...
industry, reported by American palaeoanthropologist David Braun and colleagues in 2019. This gap can either be interpreted as the loss and reinvention of stone tool technology, or
preservation bias Taphonomy is the study of how organisms decay and become fossilized or preserved in the paleontological record. The term ''taphonomy'' (from Greek , 'burial' and , 'law') was introduced to paleontology in 1940 by Soviet scientist Ivan Efremov ...
(that tools from this time gap either did not preserve for whatever reason, or sit undiscovered), the latter implying the Lomekwian evolved into the Oldowan.


Palaeoecology

From 4.5 to 4 million years ago, Lake Turkana may have swelled to upwards of , in comparison to today's ; the lake at what is now the
Koobi Fora Koobi Fora refers primarily to a region around Koobi Fora Ridge, located on the eastern shore of Lake Turkana in the territory of the nomadic Gabbra people. According to the National Museums of Kenya, the name comes from the Gabbra language ...
site possibly sat at minimum below the surface. Volcanic hills by Lomekwi pushed basalt into the lake sediments. The lake broke up and from 3.6 to 3.2 million years ago, the region was probably characterised by a series of much smaller lakes, each covering no more than . Similarly, the
bovid The Bovidae comprise the family (biology), biological family of cloven-hoofed, ruminant mammals that includes Bos, cattle, bison, Bubalina, buffalo, antelopes (including Caprinae, goat-antelopes), Ovis, sheep and Capra (genus), goats. A member o ...
remains at Lomekwi are suggestive of a wet mosaic environment featuring both grasslands and forests on a lakeside or
floodplain A floodplain or flood plain or bottomlands is an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high Discharge (hydrolog ...
. '' Theropithecus brumpti'' is the most common monkey at the site as well as the rest of the Turkana Basin at this time; this species tends to live in more forested and closed environments. At the fossiliferous ''A. afarensis'' Hadar site in Ethiopia, '' Theropithecus darti'' is the most common monkey, which tends to prefer drier conditions conducive to wood- or grassland environments. Leakey and colleagues argued this distribution means ''Kenyanthropus'' was living in somewhat more forested environments than more northerly ''A. afarensis''. ''Kenyanthropus'', ''A. afarensis'', and '' A. deyiremeda'' all coexisted in the same time and region, and, because their anatomy largely diverges in areas relevant to chewing, they may have practised
niche partitioning In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of resources and competitors (for e ...
and foraged for different food items.


See also

*
List of fossil sites This list of fossil sites is a worldwide list of localities known well for the presence of fossils. Some entries in this list are notable for a single, unique find, while others are notable for the large number of fossils found there. Many of ...
*
List of human evolution fossils The following tables give an overview of notable finds of Hominini, hominin fossils and Skeleton, remains relating to human evolution, beginning with the formation of the tribe Hominini (the divergence of the Chimpanzee–human last common ancest ...


References


External links


The flat faced man of Kenya (''Nature'')

BBC Science article

A picture of ''Kenyathropus platyops'' at the American Museum of Natural History

Human Timeline (Interactive)
Smithsonian,
National Museum of Natural History The National Museum of Natural History (NMNH) is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. With 4.4 ...
(August 2016). {{Taxonbar, from=Q311123, from2=Q1813596, from3=Q56425720, from4=Q107742 Hominini Prehistoric primate genera Pliocene primates Fossil taxa described in 2001 Prehistoric Kenya Pliocene mammals of Africa