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Lucy is the common name of AL 288-1, several hundred pieces of bone fossils representing 40 percent of the skeleton of a female of the hominin species ''Australopithecus afarensis''. In Ethiopia, the assembly is also known as Dinkinesh, which means "you are marvelous" in the Amharic language. Lucy was discovered in 1974 near the village Hadar in the Awash Valley of the Afar Triangle in Ethiopia by paleoanthropologist Donald Johanson.〔 The Lucy specimen is an early australopithecine and is dated to about 3.2 million years ago. The skeleton presents a small skull akin to that of non-hominin apes, plus evidence of a walking-gait that was bipedal and upright, akin to that of humans (and other hominins); this combination supports the (debated) view of human evolution that bipedalism preceded increase in brain size.〔''Hadar'' entry in ''Encyclopædia'' (2008).〕 "Lucy" acquired her name from the song "Lucy in the Sky with Diamonds" by the Beatles, which was played loudly and repeatedly in the expedition camp all evening after the excavation team's first day of work on the recovery site. After public announcement of the discovery, Lucy captured much public interest, becoming almost a household name at the time. Beginning in 2007, the fossil assembly and associated artifacts were exhibited publicly in an extended six-year tour of the United States; the exhibition was called ''Lucy’s Legacy: The Hidden Treasures of Ethiopia.'' Lucy became famous in the US and around the world, and was returned to Ethiopia in 2013. ==Discovery== French geologist and paleoanthropologist Maurice Taieb discovered the Hadar Formation for paleoanthropology in 1972 in the Afar Triangle of Ethiopia; 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. 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. In November 1973, 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 from the site where "Lucy" subsequently was found, in a rock stratum deeper than that in which the Lucy fragments were found.〔("Letter from Donald Johanson, August 8, 1989" ), Lucy's Knee Joint, Talk Origins〕 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. 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.〔(【引用サイトリンク】title=Institute of Human Origins: Lucy's Story )〕 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. 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.〔 Lucy was tall, weighed , 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. 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.〔(【引用サイトリンク】 publisher=BBC Home )〕 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 , it had evolved much earlier than the ''afarensis'' species, and there is debate about whether Ardipithecus achieved full status as a hominin. 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. ==Age estimates of the Lucy fossil== 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. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lucy (Australopithecus)」の詳細全文を読む スポンサード リンク
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