Тауң баласы - ежелгі гоминид қаңқасы

Hominin fossil

The Taung Child (or Taung Baby) is the fossilised skull of a young Australopithecus africanus. It was discovered in 1924 by quarrymen working for the Northern Lime Company in Taung, South Africa. Raymond Dart described it as a new species in the journal Nature in 1925. The Taung skull is in repository at the University of Witwatersrand. Dean Falk, a specialist in brain evolution, has called it "the most important anthropological fossil of the twentieth century."

In the early 20th century, the workers at limestone quarries in Southern Africa routinely uncovered fossils from the tufa formations that they mined. The tufa did not form consistently, and over time cavities were left open and they became beneficial areas for animals to take shelter in. As a result, many bones began to build up in these areas. These areas were mostly sandstone, and they stood in the way of successful mining. So, miners would use explosives to clear these areas, and discard all the debris. However, many fossils began to show up, and these were saved by many of the miners. Many were of extinct fauna, which included baboons and other primates, and the more complete or somehow more interesting fossils were kept as curiosities by the Europeans who managed operations.

In 1924, workers at the Buxton Limeworks, near Taung, showed a fossilized primate skull to E. G. Izod, the visiting director of the Northern Lime Company, the managing company of the quarry. The director gave it to his son, Pat Izod, who displayed it on the mantle over the fireplace. When Josephine Salmons, a friend of the Izod family, paid a visit to Pat's home, she noticed the primate skull, identified it as from an extinct monkey and realised its possible significance to her mentor, Raymond Dart. Salmons was the first female student of Dart, an anatomist at the University of Witwatersrand. Salmons was permitted to take the fossilized skull and presented it to Dart, who also recognized it as a significant find. Dart asked the company to send any more interesting fossilized skulls that were unearthed. When a consulting geologist, Robert Young, paid a visit to the quarry office, the director, A. E. Speirs, presented him with a collection of fossilised primate skulls that had been gathered by a miner, Mr. De Bruyn. A. E. Speirs was using a particular fossil as a paperweight, and Young asked him for this as well. Young sent some of the skulls back to Dart. When Dart examined the contents of the crate, he found a fossilized endocast of a skull showing the impression of a complex brain. He quickly searched through the rest of the fossils in the crates, and matched it to a fossilized skull of a juvenile primate, which had a shallow face and fairly small teeth. Only forty days after he first saw the fossil, Dart completed a paper that named the species of Australopithecus africanus, the "southern ape from Africa", and described it as "an extinct race of apes intermediate between living anthropoids and man". The paper appeared in the 7 February 1925 issue of the journal Nature. The fossil was soon nicknamed the Taung Child.

Scientists were initially reluctant to accept that the Taung Child and the new genus Australopithecus were ancestral to modern humans. In the issue of Nature immediately following the one in which Dart's paper was published, several authorities in British paleoanthropology criticized Dart's conclusion. Three of the four scholars were members of the Piltdown Man committee: Sir Arthur Keith, Grafton Elliot Smith, and Sir Arthur Smith Woodward. They were much more skeptical about this fossil's place in evolutionary history, and believed it deserved to be categorized as a chimp or gorilla rather than a human ancestor. However, Dart still had the hesitant support of W. L. H. Duckworth, but he still asked for more information on the brain to support this claim. Dart's former mentor, Keith, one of the most prominent anatomists of his time, claimed that there was insufficient evidence to accept Dart's claim that Australopithecus was transitional between apes and humans. Grafton Elliot Smith stated that he needed more evidence and a larger picture of the skull before he could judge the significance of the new fossil. Arthur Smith Woodward dismissed the Taung Child as having "little bearing" on the issue of "whether the direct ancestors of man are to be sought in Asia or Africa". The critiques became more fervent a few months later. Elliot Smith concluded that the Taung fossil was "essentially identical" to the skull of "the infant gorilla and chimpanzee". Infant apes appear more human like because of the "shape of their forehead and the lack of fully developed brow ridges". Subsequently, Falk unearthed an unpublished manuscript that Dart completed in 1929 in the Archives of the University of Witwatersrand, which provides a much more thorough description and analysis of the Taung endocast than Dart's earlier announcement in Nature. This was barred from being published to Dart's dismay in 1931. It remains unpublished in these archives. In this writing, Falk discovered that she and Dart had come to similar conclusions surrounding the evolutionary process of the brain that Taung indicates. Whereas Dart had identified only two potential sulci on the Taung endocast in 1925, he identified and illustrated 14 additional sulci in this still unpublished monograph. There, too, Dart detailed how Taung's endocast was expanded globally in three different regions, contrary to the suggestion that he believed hominin brains evolved back end first, in a so called mosaic fashion. Comparison of the Taung Child fossil to the skull of a nine year old modern child suggest that A. africanus had a growth rate to adolescence more similar to that of modern apes, like chimpanzees (genus Pan), than to that of modern Homo sapiens. The creature stood tall and weighed between It had a cranial capacity of 400–500 cc, which is comparable to that of a modern adult chimpanzee. Because mature brain size is attained within the first few years of life, the relatively small size is unlikely to be attributed to the specimen being a juvenile. The skull also possesses features more commonly found in humans than apes, including a rising forehead and round eye sockets. Although the lower portion of the nose resembled a chimpanzee, the overall shorter shape was human like. Likewise, the lower portion of the face was protruded, albeit to a lesser degree than in modern apes. A bony shelf found within the inner jaw of apes could not be found. Dart opted to describe the remains as a "man ape" rather than as an "ape man" to highlight the more human features present compared to the remains found of the more recent Pithecanthropus erectus.

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