Australopithecus Fossils Found East of the Great Rift Valley

Australopithecus Fossils Found East of the Great Rift Valley


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New fossils from Kenya suggest that an early hominid species -- Australopithecus afarensis -- lived far eastward beyond the Great Rift Valley and much farther than previously thought. An international team of paleontologists led by Emma Mbua of Mount Kenya University and Masato Nakatsukasa of Kyoto University report findings of fossilized teeth and forearm bone from an adult male and two infant A. afarensis from an exposure eroded by the Kantis River in Ongata-Rongai, a settlement in the outskirts of Nairobi.

"So far, all other A. afarensis fossils had been identified from the center of the Rift Valley," explains Nakatsukasa. "A previous Australopithecus bahrelghazali discovery in Chad confirmed that our hominid ancestor's distribution covered central Africa, but this was the first time an Australopithecus fossil has been found east of the Rift Valley. This has important implications for what we understand about our ancestor's distribution range, namely that Australopithecus could have covered a much greater area by this age."

A. afarensis is believed to have lived 3,700,000-3,000,000 years ago, as characterized by fossils like "Lucy" from Ethiopia.

Cast of the remains of "Lucy". ( CC BY-SA 3.0 )

Stable isotope analysis revealed that the Kantis region was humid, but had a plain-like environment with fewer trees compared to other sites in the Great Rift Valley where A. afaransis fossils had previously appeared. "The hominid must have discovered suitable habitats in the Kenyan highlands. It seems that A. afaransis was good at adapting to varying environments," notes Nakatsukasa.

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The team's survey also turned up masses of mammal fossils, including a few that probably belong to new species of bovids or baboons.

A reconstruction of a female A. afarensis.

The authors write that the Kantis site was first noted in a 1991 geological survey. At that time, a farmer said that he and his family had come across fossilized bones from Kantis in the 1970s, although they did not recognize their importance. Following airing of Kenyan television programs on paleontological research, locals gradually started to appreciate the fossils. Since then, Kantis and other sites have been identified thanks to fossil notifications from the local population.

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The team welcomes this achievement not only for its academic implications, but also for the benefits to the local community. "Kantis is in the vicinity of Nairobi, a major city," said Nakatsukasa. "We hope that the discovery of the new site and the fossils will aid in increasing tourism, and in improving educational awareness of the local community."

Featured image: A. afarensis reconstruction ( CC BY-SA 3.0 ), an adult left ulna of Australopithecus afarensis. Several fossilized teeth have also been found in the Kantis site. Credit: Image courtesy of Kyoto University

The article ‘ Australopithecus fossils found east of the Great Rift Valley by Kyoto University was originally published on Science Daily .

Source: Kyoto University. "Australopithecus fossils found east of the Great Rift Valley: New remains demonstrate early hominid's adaptability." ScienceDaily. ScienceDaily, 24 March 2016.


    Cradle of Humankind

    The paleoanthropological site self-proclaimed [1] [2] [3] as the Cradle of Humankind is located about 50 km (31 mi) northwest of Johannesburg, South Africa, in the Gauteng province. Declared a World Heritage site by UNESCO in 1999, [4] the site currently occupies 47,000 hectares (180 sq mi) [5] and contains a complex of limestone caves. The registered name of the site in the list of World Heritage sites is Fossil Hominid Sites of South Africa.

    According to existing archaeological and fossil evidence, however, the Cradle of Humankind (originally known as Cradle of Mankind) is the Afar Triangle in East Africa, which is often referred to as the Cradle of Humanity. [6] [7]

    The Sterkfontein Caves were the site of the discovery of a 2.3-million-year-old fossil Australopithecus africanus (nicknamed "Mrs. Ples"), found in 1947 by Robert Broom and John T. Robinson. The find helped corroborate the 1924 discovery of the juvenile Australopithecus africanus skull known as the "Taung Child", by Raymond Dart, at Taung in the North West Province of South Africa, where excavations still continue.

    Nearby, but not in the site, the Rising Star Cave system contains the Dinaledi Chamber (chamber of stars), in which were discovered fifteen fossil skeletons of an extinct species of hominin, provisionally named Homo naledi.

    Sterkfontein alone has produced more than a third of early hominid fossils ever found prior to 2010. [8] The Dinaledi Chamber contains over 1,500 H. naledi fossils, the most extensive discovery of a single hominid species ever found in Africa. [9]


    Australopithecus: Human ancestors better at adapting to new environments than thought

    Newly discovered fossils in Kenya suggest that early hominids, the Australopithecus afarensis, were present in far more regions than scientists previously believed. The discovery of fossils in an area they were not to have thought to have lived shows the species was better at adapting to new regions than thought.

    The findings, published in the Journal of Human Evolution, were made by an international team from Mount Kenya University and Kyoto University, in Japan.

    The palaeontologists were exploring a settlement near Kenya's capital Nairobi called Ongata-Rongai, when they came across fossilised teeth and a forearm bone belonging to a male adult and two children, from the same Australopithecus group as the famous "Lucy", the fossilised female partial s keleton discovered in 1974. The fossils had been exposed due to erosion by the Kantis River.

    Understanding spatial distribution

    This discovery is a major step to understanding how our prehistorical ancestors moved around Africa and settled down in different areas of the continent. Though previous findings had already challenged the belief that all Australopithecus lived in the Great Rift Valley (the ridge system running from the north to the south of Kenya), the fact that Australopithecus afarensis is found outside of the area, to the east, is something of a novelty.

    It is the first time fossils have been found east of the Rift Valley Wikipedia Commons

    "So far, all other A. afarensis fossils had been identified from the centre of the [Great] Rift Valley," says research co-leader Masato Nakatsukasa.

    "A previous Australopithecus bahrelghazali discovery in Chad confirmed that our hominid ancestors' distribution covered central Africa, but this was the first time an Australopithecus fossil has been found east of the [Great] Rift Valley.

    "This has important implications for what we understand about our ancestors' distribution range, namely that Australopithecuscould have covered a much greater area by this age."

    This is all the more surprising, because the environment and the climate is not exactly similar in the different regions where the fossils were found. The Kantis region is humid, but its plain-like environment, with few trees, make it a very different place than the Great Rift Valley. "The hominid must have discovered suitable habitats in the Kenyan highlands. It seems that A. afaransis was good at adapting to varying environments," Nakatsukasa adds.

    Beyond these palaeontological discoveries, which have key implications for our understanding of Lucy's contemporaries, the team also hopes this will have a positive impact on the communities that live near the fossils, boosting tourism and renewing interest for their region.


    Australopithecus fossils found east of the Great Rift Valley

    New remains demonstrate adaptability of this precursor to early humans.

    KYOTO UNIVERSITY—New fossils from Kenya suggest that an early hominid species— Australopithecus afarensis—lived far eastward beyond the Great Rift Valley and much farther than previously thought. An international team of paleontologists led by Emma Mbua of Mount Kenya University and Masato Nakatsukasa of Kyoto University report findings of fossilized teeth and forearm bone from an adult male and two infant A. afarensis from an exposure eroded by the Kantis River in Ongata-Rongai, a settlement in the outskirts of Nairobi.

    “So far, all other A. afarensis fossils had been identified from the center of the Rift Valley,” explains Nakatsukasa. “A previous Australopithecus bahrelghazali discovery in Chad confirmed that our hominid ancestor’s distribution covered central Africa, but this was the first time an Australopithecus fossil has been found east of the Rift Valley. This has important implications for what we understand about our ancestor’s distribution range, namely that Australopithecus could have covered a much greater area by this age.”

    A. afarensis is believed to have lived 3,700,000-3,000,000 years ago, as characterized by fossils like “ Lucy ” from Ethiopia.

    Above: A forensic facial reconstruction of A. afarensis based on fossil evidence. Cicero Moraes, Wikimedia Commons

    Stable isotope analysis revealed that the Kantis region was humid, but had a plain-like environment with fewer trees compared to other sites in the Great Rift Valley where A. afaransis fossils had previously appeared. “The hominid must have discovered suitable habitats in the Kenyan highlands. It seems that A. afaransis was good at adapting to varying environments,” notes Nakatsukasa.

    The team’s survey also turned up masses of mammal fossils, including a few that probably belong to new species of bovids or baboons.

    The authors write that the Kantis site was first noted in a 1991 geological survey. At that time, a farmer said that he and his family had come across fossilized bones from Kantis in the 1970s, although they did not recognize their importance. Following airing of Kenyan television programs on paleontological research, locals gradually started to appreciate the fossils. Since then, Kantis and other sites have been identified thanks to fossil notifications from the local population.

    The team welcomes this achievement not only for its academic implications, but also for the benefits to the local community. “Kantis is in the vicinity of Nairobi, a major city,” said Nakatsukasa. “We hope that the discovery of the new site and the fossils will aid in increasing tourism, and in improving educational awareness of the local community.”


    Australopithecus East of the Great Rift Valley

    An international team of paleontologists led by Emma Mbua of Mount Kenya University and Masato Nakatsukasa of Kyoto University report findings of fossilized teeth and forearm bone from an adult male and two infant A. afarensis from an exposure eroded by the Kantis River in Ongata-Rongai, a settlement in the outskirts of Nairobi. CREDIT Masato Nakatsukasa / Kyoto University

    Late last month, an international team of paleontologists led by Emma Mbua of Mount Kenya University and Masato Nakatsukasa of Kyoto University reported the findings of fossilized teeth and forearm bone from an adult male and two infant A. afarensis from an exposure eroded by the Kantis River in Ongata-Rongai, a settlement in the outskirts of Nairobi. They published their findings Journal of Human Evolution.

    So far, all other A. afarensis fossils had been identified from the center of the Rift Valley. Stable isotope analysis revealed that the Kantis region was humid, but had a plain-like environment with fewer trees compared to other sites in the Great Rift Valley where A. afaransis fossils had previously appeared… It seems that A. afaransis was good at adapting to varying environments.


    Australopithecus fossils found east of the Great Rift Valley

    New fossils from Kenya suggest that an early hominid species -- Australopithecus afarensis -- lived far eastward beyond the Great Rift Valley: much farther than previously thought. An international team of paleontologists led by Emma Mbua of Mount Kenya University and Masato Nakatsukasa of Kyoto University report findings of fossilized teeth and forearm bone from an adult male and two infant A. afarensis from an exposure eroded by the Kantis River in Ongata-Rongai, a settlement in the outskirts of Nairobi.

    "So far, all other A. afarensis fossils had been identified from the center of the Rift Valley," explains Nakatsukasa. "A previous Australopithecus bahrelghazali discovery in Chad confirmed that our hominid ancestor's distribution covered central Africa, but this was the first time an Australopithecus fossil has been found east of the Rift Valley. This has important implications for what we understand about our ancestor's distribution range, namely that Australopithecus could have covered a much greater area by this age."

    A. afarensis is believed to have lived 3,700,000-3,000,000 years ago, as characterized by fossils like “Lucy” from Ethiopia.

    Stable isotope analysis revealed that the Kantis region was humid, but had a plain-like environment with fewer trees compared to other sites in the Great Rift Valley where A.afaransis fossils had previously appeared. "The hominid must have discovered suitable habitats in the Kenyan highlands. It seems that A. afaransis was good at adapting to varying environments," notes Nakatsukasa.

    The team's survey also turned up masses of mammal fossils, including a few that probably belong to new species of bovids or baboons.

    The authors write that the Kantis site was first noted in a 1991 geological survey. At that time, a farmer said that he and his family had come across fossilized bones from Kantis in the 1970s, although they did not recognize their importance. Following airing of Kenyan television programs on paleontological research, locals gradually started to appreciate the fossils. Since then, Kantis and other sites have been identified thanks to fossil notifications from the local population.

    The team welcomes this achievement not only for its academic implications, but also for the benefits to the local community. "Kantis is in the vicinity of Nairobi, a major city," said Nakatsukasa. "We hope that the discovery of the new site and the fossils will aid in increasing tourism, and in improving educational awareness of the local community."


    An adult left ulna of Australopithecus afarensis . Several fossilized teeth have also been found in the Kantis site.

    Paper Information

    Mbua, E. et al.
    "Kantis: A new Australopithecus site on the shoulders of the Rift Valley near Nairobi, Kenya"
    Journal of Human Evolution, May 2016


    New Fossils of Australopithecus afarensis Found in Kenya

    Fieldwork at the Pliocene site of Kantis, Kenya, has yielded fossilized teeth and forearm bone attributable to Australopithecus afarensis, a hominid species that lived from 3.85 to 2.95 million years ago.

    Forensic facial reconstruction of Australopithecus afarensis. Image credit: Cicero Moraes / CC BY-SA 3.0.

    The new fossils – from an adult male and two infant Australopithecus afarensis – suggest that this hominid species lived far eastward beyond the Great Rift Valley and much farther than previously thought.

    The fossils all date to between 3.5 and 3.3 million years ago, according to a team of scientists led by Dr. Emma Mbua of Mount Kenya University and Dr. Masato Nakatsukasa of Kyoto University.

    Australopithecus afarensis was previously known from northern Ethiopia to northern Tanzania,” the researchers said. “The presence of A. afarensis in the Turkana basin of Kenya is contested.”

    “The Kantis hominin specimens are the first clear evidence of this species in Kenya.”

    “In addition, Kantis is unique in Kenya in its location on the eastern shoulder of the Gregory Rift Valley, hence expanding the A. afarensis range east of the Rift Valley.”

    According to the team, the Kantis region was humid, but had a plain-like environment with fewer trees compared to other sites in the Great Rift Valley where Australopithecus afarensis fossils had previously appeared.

    Australopithecus afarensis bone from Kenya. Eroded parts are shown with shading. Abbreviations: sp and arrow heads – supinator crest, ic – interosseous crest, br – insertion of the brachialis muscle, fd – origin of the flexor digitorum superficialis and pronator teres muscles. Scale – 5 cm. Image credit: Masato Nakatsukasa, Kyoto University.

    “The hominid must have discovered suitable habitats in the Kenyan highlands,” Dr. Nakatsukasa said.

    “It seems that A. afarensis was good at adapting to varying environments.”

    The team’s survey also turned up masses of mammal fossils, including a few that probably belong to new species of bovids or baboons.

    The Kantis fossils were described in the Journal of Human Evolution.


    Contents

    Organizing the expedition Edit

    French geologist and paleoanthropologist Maurice Taieb discovered the Hadar Formation for paleoanthropology in 1970 in the Afar Triangle of Ethiopia in Hararghe region he recognized its potential as a likely repository of the fossils and artifacts of human origins. Taieb formed the International Afar Research Expedition (IARE) and invited three prominent international scientists to conduct research expeditions into the region. These were: Donald Johanson, an American paleoanthropologist and curator at the Cleveland Museum of Natural History, who later founded the Institute of Human Origins, now part of Arizona State University Mary Leakey, the noted British paleoanthropologist and Yves Coppens, a French paleoanthropologist now based at the Collège de France which is considered to be France's most prestigious research establishment. An expedition was soon mounted with four American and seven French participants in the autumn of 1973 the team began surveying sites around Hadar for signs related to the origin of humans. [9]

    First find Edit

    In November 1971, near the end of the first field season, Johanson noticed a fossil of the upper end of a shinbone, which had been sliced slightly at the front. The lower end of a femur was found near it, and when he fitted them together, the angle of the knee joint clearly showed that this fossil, reference AL 129-1, was an upright walking hominin. This fossil was later dated at more than three million years old—much older than other hominin fossils known at the time. The site lay about 2.5 kilometres (1.6 mi) from the site where "Lucy" subsequently was found, in a rock stratum 60 metres (200 ft) deeper than that in which the Lucy fragments were found. [10] [11]

    Subsequent findings Edit

    The team returned for the second field season the following year and found hominin jaws. Then, on the morning of 24 November 1974, near the Awash River, Johanson abandoned a plan to update his field notes and joined graduate student Tom Gray to search Locality 162 for bone fossils. [12] [13] [14] [15] [1] [2]

    By Johanson's later (published) accounts, both he and Tom Gray spent two hours on the increasingly hot and arid plain, surveying the dusty terrain. On a hunch, Johanson decided to look at the bottom of a small gully that had been checked at least twice before by other workers. At first view nothing was immediately visible, but as they turned to leave a fossil caught Johanson's eye an arm bone fragment was lying on the slope. Near it lay a fragment from the back of a small skull. They noticed part of a femur (thigh bone) a few feet (about one meter) away. As they explored further, they found more and more bones on the slope, including vertebrae, part of a pelvis, ribs, and pieces of jaw. They marked the spot and returned to camp, excited at finding so many pieces apparently from one individual hominin. [3] [16]

    In the afternoon, all members of the expedition returned to the gully to section off the site and prepare it for careful excavation and collection, which eventually took three weeks. That first evening they celebrated at the camp at some stage during the evening they named fossil AL 288-1 "Lucy", after the Beatles' song "Lucy in the Sky with Diamonds", which was being played loudly and repeatedly on a tape recorder in the camp. [17]

    Over the next three weeks the team found several hundred pieces or fragments of bone with no duplication, confirming their original speculation that the pieces were from a single individual ultimately, it was determined that an amazing 40 percent of a hominin skeleton was recovered at the site. Johanson assessed it as female based on the one complete pelvic bone and sacrum, which indicated the width of the pelvic opening. [17]

    Assembling the pieces Edit

    Lucy was 1.1 m (3 ft 7 in) tall, [18] weighed 29 kg (64 lb), and (after reconstruction) looked somewhat like a chimpanzee. The creature had a small brain like a chimpanzee, but the pelvis and leg bones were almost identical in function to those of modern humans, showing with certainty that Lucy's species were hominins that had stood upright and had walked erect. [19]

    Reconstruction in Cleveland Edit

    With the permission of the government of Ethiopia, Johanson brought all the skeletal fragments to the Cleveland Museum of Natural History in Ohio, where they were stabilized and reconstructed by anthropologist Owen Lovejoy. Lucy the pre-human hominid and fossil hominin, captured much public notice she became almost a household name at the time. Some nine years later, and now assembled altogether, she was returned to Ethiopia. [20]

    Later discoveries Edit

    Additional finds of A. afarensis were made during the 1970s and forward, gaining for anthropologists a better understanding of the ranges of morphic variability and sexual dimorphism within the species. An even more complete skeleton of a related hominid, Ardipithecus, was found in the same Awash Valley in 1992. "Ardi", like "Lucy", was a hominid-becoming-hominin species, but, dated at 4.4 million years ago , it had evolved much earlier than the afarensis species. Excavation, preservation, and analysis of the specimen Ardi was very difficult and time-consuming work was begun in 1992, with the results not fully published until October 2009. [21]

    Initial attempts were made in 1974 by Maurice Taieb and James Aronson in Aronson's laboratory at Case Western Reserve University to estimate the age of the fossils using the potassium-argon radiometric dating method. These efforts were hindered by several factors: the rocks in the recovery area were chemically altered or reworked by volcanic activity datable crystals were very scarce in the sample material and there was a complete absence of pumice clasts at Hadar. (The Lucy skeleton occurs in the part of the Hadar sequence that accumulated with the fastest rate of deposition, which partly accounts for her excellent preservation.)

    Fieldwork at Hadar was suspended in the winter of 1976–77. When it was resumed thirteen years later in 1990, the more precise argon-argon technology had been updated by Derek York at the University of Toronto. By 1992 Aronson and Robert Walter had found two suitable samples of volcanic ash—the older layer of ash was about 18 m below the fossil and the younger layer was only one meter below, closely marking the age of deposition of the specimen. These samples were argon-argon dated by Walter in the geochronology laboratory of the Institute of Human Origins at 3.22 and 3.18 million years. [22]

    Ambulation Edit

    One of the most striking characteristics of the Lucy skeleton is a valgus knee, [23] which indicates that she normally moved by walking upright. Her femur presents a mix of ancestral and derived traits. The femoral head is small and the femoral neck is short both are primitive traits. The greater trochanter, however, is clearly a derived trait, being short and human-like—even though, unlike in humans, it is situated higher than the femoral head. The length ratio of her humerus (arm) to femur (thigh) is 84.6%, which compares to 71.8% for modern humans, and 97.8% for common chimpanzees, indicating that either the arms of A. afarensis were beginning to shorten, the legs were beginning to lengthen, or both were occurring simultaneously. Lucy also had a lordose curve, or lumbar curve, another indicator of habitual bipedalism. [24] She apparently had physiological flat feet, not to be confused with pes planus or any pathology, even though other afarensis individuals appear to have had arched feet. [25]

    Pelvic girdle Edit

    Johanson recovered Lucy's left innominate bone and sacrum. Though the sacrum was remarkably well preserved, the innominate was distorted, leading to two different reconstructions. The first reconstruction had little iliac flare and virtually no anterior wrap, creating an ilium that greatly resembled that of an ape. However, this reconstruction proved to be faulty, as the superior pubic rami would not have been able to connect were the right ilium identical to the left.

    A later reconstruction by Tim White showed a broad iliac flare and a definite anterior wrap, indicating that Lucy had an unusually broad inner acetabular distance and unusually long superior pubic rami. Her pubic arch was over 90 degrees and derived that is, similar to modern human females. Her acetabulum, however, was small and primitive.

    Cranial specimens Edit

    The cranial evidence recovered from Lucy is far less derived than her postcranium. Her neurocranium is small and primitive, while she possesses more spatulate canines than other apes. The cranial capacity was about 375 to 500 cc.

    Rib cage and plant-based diet Edit

    Australopithecus afarensis seems to have had the same conical rib-cage found in today's non-human great apes (like the chimpanzee and gorilla), which allows room for a large stomach and the longer intestine needed for digesting voluminous plant matter. Fully 60% of the blood supply of non-human apes is used in the digestion process, greatly impeding the development of brain function (which is limited thereby to using about 10% of the circulation). The heavier musculature of the jaws—those muscles operating the intensive masticatory process for chewing plant material—similarly would also limit development of the braincase. During evolution of the human lineage these muscles seem to have weakened with the loss of the myosin gene MYH16, a two base-pair deletion that occurred about 2.4 million years ago. [ citation needed ]

    Other findings Edit

    A study of the mandible across a number of specimens of A. afarensis indicated that Lucy's jaw was rather unlike other hominins, having a more gorilla-like appearance. [26] Rak et al. concluded that this morphology arose "independently in gorillas and hominins", and that A. afarensis is "too derived to occupy a position as a common ancestor of both the Homo and robust australopith clades". [27]

    Work at the American Museum of Natural History uncovered a possible Theropithecus vertebral fragment that was found mixed in with Lucy's vertebrae, but confirmed the remainder belonged to her. [28]

    Lucy's cause of death cannot be determined. The specimen does not show the signs of post-mortem bone damage characteristic of animals killed by predators and then scavenged. The only visible damage is a single carnivore tooth mark on the top of her left pubic bone, believed to have occurred at or around the time of death, but which is not necessarily related to her death. Her third molars were erupted and slightly worn and, therefore, it was concluded that she was fully matured with completed skeletal development. There are indications of degenerative disease to her vertebrae that do not necessarily indicate old age. It is believed that she was a mature but young adult when she died, about 12 years old. [29]

    In 2016 researchers at the University of Texas at Austin suggested that Lucy died after falling from a tall tree. [30] [31] Donald Johanson and Tim White disagreed with the suggestions. [32]

    The Lucy skeleton is preserved at the National Museum of Ethiopia in Addis Ababa. A plaster replica is publicly displayed there instead of the original skeleton. A cast of the original skeleton in its reconstructed form is displayed at the Cleveland Museum of Natural History. [33] At the American Museum of Natural History in New York City a diorama presents Australopithecus afarensis and other human predecessors, showing each species and its habitat and explaining the behaviors and capabilities assigned to each. A cast of the skeleton as well as a corpus reconstruction of Lucy is displayed at The Field Museum in Chicago.

    US tour Edit

    A six-year exhibition tour of the United States was undertaken during 2007–13 it was titled Lucy's Legacy: The Hidden Treasures of Ethiopia and it featured the actual Lucy fossil reconstruction and over 100 artifacts from prehistoric times to the present. The tour was organized by the Houston Museum of Natural Science and was approved by the Ethiopian government and the U.S. State Department. [34] A portion of the proceeds from the tour was designated to modernizing Ethiopia's museums.

    There was controversy in advance of the tour over concerns about the fragility of the specimens, with various experts including paleoanthropologist Owen Lovejoy and anthropologist and conservationist Richard Leakey publicly stating their opposition, while discoverer Don Johanson, despite concerns for the possibility of damage, felt the tour would raise awareness of human origins studies. The Smithsonian Institution, Cleveland Museum of Natural History and other museums declined to host the exhibits. [8] [35]

    The Houston Museum made arrangements for exhibiting at ten other museums, including the Pacific Science Center in Seattle. [8] In September 2008, between the exhibits in Houston and Seattle, the skeletal assembly was taken to the University of Texas at Austin for 10 days to perform high-resolution CT scans of the fossils. [36]

    Lucy was exhibited at the Discovery Times Square Exposition in New York City from June until October 2009. [37] In New York, the exhibition included Ida (Plate B), the other half of the recently announced Darwinius masilae fossil. [38] She was also exhibited in Mexico at the Mexico Museum of Anthropology until its return to Ethiopia in May 2013.


    Australopithecus fossils found east of the Great Rift Valley

    New fossils from Kenya suggest that an early hominid species — Australopithecus afarensis — lived far eastward beyond the Great Rift Valley: much farther than previously thought. An international team of paleontologists led by Emma Mbua of Mount Kenya University and Masato Nakatsukasa of Kyoto University report findings of fossilized teeth and forearm bone from an adult male and two infant A. afarensis from an exposure eroded by the Kantis River in Ongata-Rongai, a settlement in the outskirts of Nairobi.

    “So far, all other A. afarensis fossils had been identified from the center of the Rift Valley,” explains Nakatsukasa. “A previous Australopithecus bahrelghazali discovery in Chad confirmed that our hominid ancestor’s distribution covered central Africa, but this was the first time an Australopithecus fossil has been found east of the Rift Valley. This has important implications for what we understand about our ancestor’s distribution range, namely that Australopithecus could have covered a much greater area by this age.”

    A. afarensis is believed to have lived 3,700,000-3,000,000 years ago, as characterized by fossils like “Lucy” from Ethiopia.

    Stable isotope analysis revealed that the Kantis region was humid, but had a plain-like environment with fewer trees compared to other sites in the Great Rift Valley where A.afaransis fossils had previously appeared. “The hominid must have discovered suitable habitats in the Kenyan highlands. It seems that A. afaransis was good at adapting to varying environments,” notes Nakatsukasa.

    The team’s survey also turned up masses of mammal fossils, including a few that probably belong to new species of bovids or baboons.

    The authors write that the Kantis site was first noted in a 1991 geological survey. At that time, a farmer said that he and his family had come across fossilized bones from Kantis in the 1970s, although they did not recognize their importance. Following airing of Kenyan television programs on paleontological research, locals gradually started to appreciate the fossils. Since then, Kantis and other sites have been identified thanks to fossil notifications from the local population.

    The team welcomes this achievement not only for its academic implications, but also for the benefits to the local community. “Kantis is in the vicinity of Nairobi, a major city,” said Nakatsukasa. “We hope that the discovery of the new site and the fossils will aid in increasing tourism, and in improving educational awareness of the local community.”


    Rift Valley

    A rift valley is a lowland region that forms where Earth&rsquos tectonic plates move apart, or rift.

    Earth Science, Geology, Geography, Physical Geography

    Many of Earth&rsquos deepest rift valleys are found underwater, dividing long mountain ranges called mid-ocean ridges. As tectonic plates move away from one another at mid-ocean ridges, molten rock from the mantle may well up and harden as it contacts the frigid sea, forming new oceanic crust at the bottom of the rift valley.

    In the northern Mid-Atlantic Ridge, the North American plate and the Eurasian plate are splitting apart at a rate of about 2.5 centimeters (1 inch) per year. Over millions of years, the Mid-Atlantic Ridge has formed rift valleys as wide as 15 kilometers (9 miles).

    In the Pacific Ocean, the East Pacific Rise has created rift valleys where the Pacific plate is separating from the North American plate, Cocos plate, Nazca plate, and Antarctic plate. Like many underwater rift valleys, the East Pacific Rise is dotted with hydrothermal vents. Geologic activity beneath the underwater rift valley creates these vents, which spew super-heated water and vent fluids into the ocean.

    Continental Rift Valleys

    Today, however, the Great Rift Valley exists as a cultural concept, not a scientific one. All of the rift valleys in the &ldquosystem&rdquo are connected, but not part of a single unit.

    The northern part of the system is the Jordan Rift Valley. The Jordan Rift Valley stretches from the Golan Heights, near Israel&rsquos border with Syria and Lebanon, to the Dead Sea, to the Gulf of Aqaba&mdashan inlet of the Red Sea that separates the Sinai Peninsula from the Arabian Peninsula.

    Associated with the Jordan Rift Valley to the south is the Red Sea Rift. Millions of years ago, the Arabian Peninsula was connected to Africa. Seafloor spreading caused the Arabian and African plates to rift apart. The Indian Ocean flooded the rift valley between the continents, creating the Red Sea. Today, Africa and Asia are connected by the triangle of the Sinai Peninsula. Eventually, the Red Sea Rift will separate Africa and Asia entirely and connect the Mediterranean and Red Seas.

    Photograph by Emory Kristof, National Geographic

    Grabens
    Rift valleys are sometimes called grabens, which means &ldquoditch&rdquo in German. While there is no official distinction between a graben and a rift valley, a graben usually describes a small rift valley.

    Lakes in the Rift
    Not all lakes located around the East African Rift are rift lakes. Lake Victoria, the largest freshwater lake in Africa, is not a rift lake, for instance. Lake Victoria&rsquos basin formed as mountains uplifted around it. It did not sink as a result of the nearby East African Rift.

    Finds in the Rift
    Many, many important paleoanthropological discoveries have been made in the East African Rift, nicknamed the &ldquocradle of humanity.&rdquo &ldquoLucy,&rdquo for instance, is a 3.2 million-year-old hominin skeleton that was discovered in Ethiopia, while &ldquoTurkana Boy&rdquo is a 1.5-million-year old hominin skeleton unearthed in Kenya. Scientists think that the tectonic activity that created the East African Rift also contributed to creating an environment that was ideal to the proliferation of life. The continual erosion of the cliffs of East African Rift also contribute to the dozens of discoveries.

    Valles Marineris
    The largest and deepest rift valley yet discovered is not on Earth&mdashit&rsquos on Mars. Valles Marineris was formed millions of years ago, when the rocky Martian lithosphere was still rifting and shifting. Valles Marineris reaches depths of up to 7 kilometers (4 miles) and spans about 4,000 kilometers (2,500 miles) long. That&rsquos about 20% of the diameter of Mars itself!

    Let Her Rift
    With so much volcanic and tectonic activity going on there, the East African Rift Valley is a potent power source. The United Nations Environment Program is developing a geothermal energy program that would tap into this potential. The program would convert the heat created by the rift valley&rsquos underground activity into electricity through a series of steam wells. One of the wells in Kenya produces enough power for 5,700 homes! If successful, this program would provide a sustainable energy source for millions of people, many of whom do not have access to electricity today.


    Watch the video: Origins of Genus HomoAustralopiths and Early Homo; Variation of Early Homo; Speciation of Homo


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