Kanapoi is a paleontological site in the Kenyan Rift Valley, to the southwest of Lake Turkana . Fossils were first found at Kanapoi in the 1960s by a Harvard expedition, and later by expeditions from the National Museums of Kenya .
47-567: Fossils at Kanapoi were deposited in sediments formed by lake margins, rivers and deltas between 3.4 - 4.2 Million years ago (Ma). Kanapoi fossils include a diverse array of fish, turtles, crocodiles, primates including likely human ancestors, elephants, giraffes, rhinoceroses, rodents, horses, hippos, pigs and a variety of herbivores and carnivores. The hominin Australopithecus anamensis appears in Kanapoi between 3.9 and 4.2 Ma, one of
94-531: A drainage basin with no outflow centered around the north-southwards directed Gregory Rift system in Kenya and southern Ethiopia. The deepest point of the basin is the endorheic Lake Turkana , a brackish soda lake with a very high ecological productivity in the Gregory Rift. A narrower definition for the term Turkana Basin is also in widespread use and means Lake Turkana and its environment within
141-433: A dietary shift was also found, suggesting the consumption of harder foods. This was indicated by thicker enamel in teeth and more intense molar crowns. Australopithecus anamensis is the intermediate species between Ardipithecus ramidus and Australopithecus afarensis and has multiple shared traits with humans and other apes. Fossil studies of the wrist morphology of A. anamensis have suggested knuckle-walking, which
188-481: A narrow upper face with no forehead and a large mid-face with broad zygomatic bones. Before this new discovery, it was widely believed that Australopithecus anamensis and Australopithecus afarensis evolved one right after the other in a single lineage. However, with the discovery of MRD, it suggests that A. afarensis did not result from anagenesis , but that the two hominin species lived side by side for at least 100,000 years. Australopithecus anamensis
235-535: A number of Kenyan and international researchers. Geological investigation of Kanapoi and the sedimentary sequences found there define the Kanapoi formation, a series of sedimentary deposits formed during three primary phases in the early Pliocene . The Kanapoi formation overlays Miocene-Pliocene basalt topography with substantial relief. Many of these underlying older deposits appear on the surface today through weathering or excavation of younger material. The earliest and lowest sedimentary deposits are fluvial, formed by
282-675: A number of expeditions to fossil sites around the Turkwel River , Kerio River , Kanapoi and then Lothagam . These expeditions were followed by another series launched by the International Omo Research Expedition (IORE) from 1967–76, led by Kenyan, French and American researchers. Efforts continued in the 1980s under the direction of the National Museums of Kenya and Richard Leakey. More recent work in Kanapoi has been led by Meave Leakey and
329-498: A number of fossil specimens demonstrating that human ancestors were already bipedal by this time. Kanapoi also is the site of archaeological discoveries. Count Sámuel Teleki von Szék and Ludwig von Höhnel were the first European explorers to reach Lake Turkana, in 1888. They named it Lake Rudolf after the Prince of Austro-Hungary. An expedition by French naturalist Bourg de Bozas revealed a rich assemblage of vertebrate fossils around
376-500: A series of horst and graben structures, and led to approximately 1 km of sedimentary deposits at the center of the basin every 1 million years. Sedimentary records , which become more sparse and discontinuous at greater distance from the basin center, suggest that the basin has alternated between fluvial and lacustrine regimes throughout the Plio-Pleistocene , primarily as a result of continued volcanic activity first to
423-598: A similar diet to that of the modern gorilla. The microwear patterns are consistent on all Australopithecus anamensis molar fossils regardless of location or time. This shows that their diet largely remained the same no matter what their environment. The earliest dietary isotope evidence in Turkana Basin hominin species comes from the Australopithecus anamensis . This evidence suggests that their diet consisted primarily of C3 resources, possibly however with
470-518: A singular large cusp. Additionally, A. anamensis has a narrow first milk molar that contains a large dominant cusp with minimum surface area, which may have been used for crushing. Turkana Basin The greater Turkana Basin in East Africa (mainly northwestern Kenya and southern Ethiopia , smaller parts of eastern Uganda and southeastern South Sudan ) determines a large endorheic basin ,
517-831: A small amount of C4 derived resources. Within the next 1.99- to 1.67-Ma time period, at least two distinctive hominin taxa shifted to a higher level of C4 resource consumption. At this point, there is no known cause for this shift in diet. One should recognize that this research does not by itself indicate a plant-based diet, because the isotopes can be ingested by eating animals and insects that fed on C3 and C4 resources. A. anamensis had thick, long, and narrow jaws with their side teeth arranged in parallel lines. The palate, rows of teeth, and other characteristics of A. anamensis dentition suggests that they were omnivores and their diets were composed heavily on fruit, similar to chimpanzees . These characteristics came from Ar. ramidus , who were thought to have preceded A. anamensis . Evidence of
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#1732772509811564-402: A somewhat wide jaw joint that was flat from front to back, which resembles a curvature similar to those seen in great apes. Furthermore, the ear canal of A. anamensis fossils are narrow in diameter. The ear canal most resembles that of chimpanzees and is contrasting to the wide ear canals of both later Australopithecus and Homo. The first lower premolar of A. anamensis is characterized by
611-576: Is a derived trait shared with other African apes. The A. anamensis hand portrays robust phalanges and metacarpals, and long middle phalanges. These characteristics show that the A. anamensis likely engaged in arboreal living but were largely bipedal, although not in an identical way to Homo . All Australopithecus were bipedal, small-brained, and had large teeth. A. anamensis is often confused with Australopithecus afarensis due to their similar bone structure and their habitation of woodland areas. These similarities include thick tooth enamel, which
658-449: Is a shared derived trait of all Australopithecus and shared with most Miocene hominoids. Tooth size variability in A. anamensis suggests that there was significant body size variation. In relation to their diet, A. anamensis has similarities with their predecessor Ardipithecus ramidus . A. anamensis sometimes had much larger canines than later Australopithecus species. A. anamensis and A. afarensis have similarities in
705-480: Is not fully settled whether the lineage that led to extant humans emerged in A. afarensis , or directly in A. anamensis. Fossil evidence determines that Australopithecus anamensis is the earliest hominin species in the Turkana Basin , but likely co-existed with afarensis towards the end of its existence. A. anamensis and A. afarensis may be treated as a single grouping. Preliminary analysis of
752-439: Is suggested that the environment was much wetter. While it is not definitive, it also could have been possible that nut or seed-bearing trees could have been present at Allia Bay, however more research is needed. Studies of the microwear on Australopithecus anamensis molar fossils show a pattern of long striations. This pattern is similar to the microwear on the molars of gorillas; suggesting that Australopithecus anamensis had
799-415: The A. anamensis population). The skull itself was found by Afar herder Ali Bereino in 2016. Other scientists (e.g. Alemseged, Kimbel, Ward, White) cautioned that one forehead bone fossil, which they viewed as not conclusively A. afarensis , should not be taken as disproving the possibility of anagenesis yet. In August 2019, scientists announced the discovery of MRD-VP-1/1 , a nearly intact skull, for
846-631: The Gombe basalts in the Koobi Fora formation to the east and with the Lothagam basalts further south; this event created a lake in the center of the basin and apparently established the modern, continuous depositional system of the Turkana Basin. Deposition in the Turkana Basin overall is driven primarily by subsidence , a result of rifting between the Somali and Nubian plates that has created
893-573: The Miocene world was more lush than the Pliocene . Some herbivores, like horses , responded rapidly to the spread of C4 grasslands , while other herbivores evolved more slowly, or developed a number of different responses to an increasingly arid landscape. Evolutionary studies of the Turkana Basin have found what may be major intervals of faunal turnover after the Miocene as well, most notably in
940-584: The Plio-Pleistocene era. Nearly one hundred fossil specimens of A. anamensis are known from Kenya and Ethiopia , representing over twenty individuals. The first fossils of A. anamensis discovered, are dated to around 3.8 and 4.2 million years ago and were found in Kanapoi and Allia Bay in Northern Kenya. It is usually accepted that A. afarensis emerged within this lineage. However, A. anamensis and A. afarensis appear to have lived side by side for at least some period of time, and it
987-473: The evolutionary tree . The A. anamensis find is dated to about 4.2 million years ago, the Ar. ramidus find to 4.4 million years ago, placing only 200,000 years between the two species and filling in yet another blank in the pre- Australopithecus hominid evolutionary timeline . In 2010 journal articles were published by Yohannes Haile-Selassie and others describing the discovery of around 90 fossil specimens in
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#17327725098111034-632: The humerus and the tibia . They both have human-like features and matching sizes. It has also been found that the bodies of A. anamensis are somewhat larger than those of A. afarensis . Based on additional afarensis collections from the Hadar, Ethiopia site, the A. anamensis radius is similar to that of afarensis in the lunate and scaphoid surfaces. Additional findings suggest that A. anamensis have long arms compared to modern humans. Based on fossil evidence, A. anamensis expresses high degrees of sexual dimorphism . Although considered to be
1081-417: The 2000s from stratigraphic sequences dating to about 4.1–4.2 million years ago. Specimens have been found between two layers of volcanic ash , dated to 4.17 and 4.12 million years, coincidentally when A. afarensis appears in the fossil record. The fossils (twenty one in total) include upper and lower jaws , cranial fragments, and the upper and lower parts of a leg bone ( tibia ). In addition to this,
1128-412: The Turkana Basin. The deposits include many ostracods and mollusks, most notably the gastropod Bellamya . Sediments alternate between clay and siltstone, and coarsen upward into sands until the deposition of the Kanapoi volcanic tuff. The upper sedimentary deposits grade from lake to river-dominated deposition, and include Etheria mussel reefs, sandstones, coarse gravels, occasional lake phases, and
1175-668: The Turkana grits like the Lapurr Sandstone and are dominated by eastward flowing fluvial sequences draining into the Indian Ocean; later formations from the Oligocene and Miocene are characterised by similar fluvial regimes that are not however unified under a single geological group or system . Approximately 4.2 million years ago (Ma), the region experienced widespread and significant volcanism , associated with
1222-439: The aforementioned fragment of humerus found in 1965 at the same site at Kanapoi has now been assigned to this species. In 2006, a new A. anamensis find was officially announced, extending the range of A. anamensis into northeast Ethiopia. Specifically, one site known as Asa Issie provided 30 A. anamensis fossils. These new fossils, sampled from a woodland context, include the largest hominid canine tooth yet recovered and
1269-638: The bone was published in Science in 1967; their initial analysis suggested an Australopithecus specimen and an age of 2.5 million years. Patterson and colleagues subsequently revised their estimation of the specimen's age to 4.0–4.5 mya based on faunal correlation data. In 1994, the London-born Kenyan paleoanthropologist Meave Leakey and archaeologist Alan Walker excavated the Allia Bay site and uncovered several additional fragments of
1316-643: The center of the Turkana Basin and is flanked by the Chalbi Desert to the east, the Lotakipi Plains to the north, Karasuk to the west and Samburu to the south. Included within these regions are desert scrub, desert grass and shrubland, and scattered acacia or open grasslands. The only true perennial river is the Omo River in Ethiopia, in the northern part of the basin, which discharges into
1363-573: The confines of the Gregory Rift in Kenya and Ethiopia. This includes the lower Omo River valley in Ethiopia. The Basin in the narrower definition is a site of geological subsidence containing one of the most continuous and temporally well controlled fossil records of the Plio-Pleistocene with some fossils as old as the Cretaceous . Among the Basin's critical fossiliferous sites are Lothagam , Allia Bay , and Koobi Fora . Lake Turkana sits at
1410-454: The cranial capacity is much smaller and the face is very prognathic , both of which indicate that it is earlier than A. afarensis . Known as the MRD cranium, it is that of a male who was at an "advanced developmental age" determined by the worn down post-canine teeth. The teeth show mesiodistal elongation, which differs from A. afarensis . Similar to other australopiths , however, it has
1457-407: The earliest Australopithecus femur . The find was in an area known as Middle Awash , home to several other more modern Australopithecus finds and only six miles (9.7 kilometers) away from the discovery site of Ardipithecus ramidus , the most modern species of Ardipithecus yet discovered. Ardipithecus was a more primitive hominid, considered the next known step below Australopithecus on
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1504-656: The east, and later to the south of the basin. Fossil records in the basin help establish much of what is known about African faunal evolution in the Neogene and Quaternary . As in other regions, the end-Miocene Messinian aridification crisis and global cooling trend seem to have influenced fossil assemblages in the Turkana Basin, either through migrations or de novo evolutionary events . Fossilized leaves characteristic of more mesic landscapes, faunal community compositions, and increase " C4 " or arid-adapted plant contribution to herbivore carbon intake, all suggest that
1551-399: The first time, and dated to 3.8 million years ago, of A. anamensis in Ethiopia. The skull itself was found by Afar herder Ali Bereino in 2016. This skull is important in supplementing the evolutionary lineage of hominins . The skull has a unique combination of derived and ancestral characteristics. It was determined that the cranium is older than A. afarensis through analyzing that
1598-482: The formation of soils. A late formation of green claystones appears at approximately 3.5 Ma, suggesting that these sediments may have formed with the Lokochot lake found elsewhere in the Basin. Australopithecus anamensis Australopithecus anamensis is a hominin species that lived approximately between 4.3 and 3.8 million years ago and is the oldest known Australopithecus species, living during
1645-481: The hominid, including one complete lower jaw bone which closely resembles that of a common chimpanzee (Pan troglodytes) but whose teeth bear a greater resemblance to those of a human . Based on the limited postcranial evidence available, A. anamensis appears to have been habitually bipedal, although it retained some primitive features of its upper limbs. In 1995, Meave Leakey and her associates, taking note of differences between Australopithecus afarensis and
1692-447: The lake in 1902-3, eventually inspiring Arambourg's Mission Scientifique de l'Omo in the 1930s and 1940s. Louis Leakey and what would become the National Museums of Kenya explored the fossil deposits in the 1940s, until political and military turmoil stymied work in the aftermath of World War II. Following L.H. Robbins' investigations around the southern margins of Lake Turkana and the Turkana Basin , Harvard's Bryan Patterson launched
1739-544: The lake on its northern shore and supplies the lake with more than 98% of its annual water inflow. The two intermittent rivers – which almost alone contribute the remaining 2% of water inflow – are the Turkwel River and the Kerio River in Kenya, in the western part of the basin. Much of the Turkana Basin today can be described as arid scrubland or even desert. The exception is the Omo- Gibe River valley to
1786-400: The late Pliocene and early Pleistocene, though later studies have suggested more gradual changes in herbivore community composition throughout this interval. One cause of focus on the late Pliocene and early Pleistocene is the large literature on hominin fossil remains showing an apparent " adaptive radiation " across this boundary. While previous hominin species are considered to be part of
1833-448: The layering of clays, sandstones, pebbles and cobbles washed downstream by flowing rivers. The deposits are marked by mollusks, ostracods and carbonized plant parts, and demonstrate alternating passage of river channels or meandering streams. The lowest deposits are marked by a series of volcanic ash layers. The middle sedimentary deposits are lacustrine, corresponding to the ancient Lonyuman lake interval found at other locations throughout
1880-499: The more primitive of the australopiths, A. anamensis had parts of the knee, tibia, and elbow that were different from apes, which indicates bipedalism as the species' form of locomotion. Specifically, the tibia bone of A. anamensis has a more expansive upper end with bone. In addition to the modified body parts that indicate bipedalism, A. anamensis fossils show evidence of tree climbing. Archeology finds indicate that A. anamensis had long forearms, as well as modified features of
1927-682: The new finds, assigned them to a new species, A. anamensis , deriving its name from the Turkana word anam , meaning "lake". Although the excavation team did not find hips, feet or legs, Meave Leakey believes that Australopithecus anamensis often climbed trees. Tree climbing was one behavior retained by early hominins until the appearance of the first Homo species about 2.5 million years ago. A. anamensis shares many traits with Australopithecus afarensis and may well be its direct predecessor. Fossil records for A. anamensis have been dated to between 4.2 and 3.9 million years ago, with findings in
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1974-534: The north. Important towns within the Turkana Basin include Lokitaung, Kakuma, Lodwar, Lorogumu, Ileret and Kargi. The Turkana people inhabit the west of the Basin, the Samburu and Pokot people inhabit the south, and the Nyangatom , Daasanach and Borana Oromo peoples inhabit the north and east. The oldest sedimentary records go back to the Cretaceous , including units previously informally referred to as
2021-450: The same Haile-Selassie team announced the discovery of a nearly intact skull for the first time, and dated to 3.8 mya, of A. anamensis in Ethiopia. This discovery also indicated that an earlier forehead bone fossil from 3.9 mya was A. afarensis and therefore the two species over-lapped and could not be a chronospecies (noting that this does not prevent A. afarensis being descended from A. anamensis , but would be descended from only part of
2068-515: The sole upper cranial fossil indicates A. anamensis had a smaller cranial capacity (estimated 365-370 c.c. ) than A. afarensis . The first fossilized specimen of the species, although not recognized as such at the time, was a single fragment of humerus (arm bone) found in Pliocene strata in the Kanapoi region of West Lake Turkana by a Harvard University research team in 1965. Bryan Patterson and William W. Howells 's initial paper on
2115-547: The time period 3.6 to 3.8 million years ago (mya), in the Afar area of Ethiopia, filling in the time gap between A. anamensis and Australopithecus afarensis and showing a number of features of both. This supported the idea (proposed for instance by Kimbel et al. in 2006 ) that A. anamensis and A. afarensis were in fact one evolving species (i.e. a chronospecies resulting from anagenesis ), but in August 2019, scientists from
2162-482: The wrist bone. Both the forearms and finger bones of A. anamensis indicate a potential of utilizing the upper limbs as support when operating in trees or on the ground. Forearm bones belonging to A. anamensis have been found to be 265 millimeters to 277 millimeters in length. The curved proximal hand phalanx of A. anamensis in the fossil record that contains strong ridges is indicative of its potential ability to climb. Fossil evidence reveals that A. anamensis had
2209-407: Was found in Kenya, specifically at Allia Bay, East Turkana. Through analysis of stable isotope data, it is believed that their environment had more closed woodland canopies surrounding Lake Turkana than are present today. The greatest density of woodlands at Allia Bay was along the ancestral Omo River. There was believed to be more open savanna in the basin margins or uplands. Similarly at Allia Bay, it
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