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|Asian Straight-tusked Elephant - Palaeoloxodon namadicus|
|Tweet Topic Started: Dec 23 2012, 10:30 PM (2,734 Views)|
|Taipan||Dec 23 2012, 10:30 PM Post #1|
Asian Straight-tusked Elephant - Palaeoloxodon namadicus
Temporal range: Pleistocene
Species: Palaeoloxodon namadicus
Palaeoloxodon namadicus or the Asian straight-tusked elephant, was a species of prehistoric elephant that ranged throughout Pleistocene Asia, from India (where it was first discovered) to Japan, where the indigenous Neolithic cultures hunted that particular subspecies for food. It is a descendant of the Straight-tusked Elephant.
Some authorities regard it to be a subspecies of Palaeoloxodon antiquus, the Straight-tusked Elephant, due to extreme similarities of the tusks. Their skull structure was also different from that of a modern elephant.
Several studies have attempted to estimate the size of the Asian straight-tusked elephants, as well as other prehistoric proboscideans, usually using comparisons of thigh bone length and knowledge of relative growth rates to estimate the size of incomplete skeletons.
One partial skeleton found in India in 1905 had thigh bones that likely measured 160 centimetres (5.2 ft) when complete, suggesting a total shoulder height of 4.3 metres (14 ft) and weight of 14 tonnes (14 long tons; 15 short tons) for this individual elephant.
Two partial thigh bones were found in the 19th century and would have measured 155 cm (5.1 ft) when complete. A fragment from the same locality was said to be almost a quarter larger; volumetric analysis then yields a size estimate of 5 metres (16 ft) tall at the shoulder and 22 tonnes (24 short tons) in weight. This makes P. namadicus the largest land mammal of all time, surpassing the largest indricotheres and up to twice the size of the well-known dinosaur Diplodocus carnegii. (units:tonnes = 1000 kilograms, long ton= 2,240 pounds, short ton=2000 pounds)
Extinct elephant 'survived late' in North China
By Michelle Warwicker
Reporter, BBC Nature
19 December 2012 Last updated at 11:30
Palaeoloxodon was believed to have died out around 10,000 years ago
Wild elephants living in North China 3,000 years ago belonged to the extinct genus Palaeoloxodon, scientists say.
They had previously been identified as Elephas maximus, the Asian elephant that still inhabits southern China.
The findings suggest that Palaeoloxodon survived a further 7,000 years than was thought.
The team from China examined fossilised elephant teeth and ancient elephant-shaped bronzes for the study.
The research, published in Quaternary International was carried out by a group of scientists from Shaanxi Normal University and Northwest University in Xi'an and The Institute of Geographic Sciences and Natural Resources Research, Beijing.
No wild elephants live in North China today, but historical documents indicate that they roamed freely 3,000 years ago.
For decades experts believed that the ancient elephants were E. maximus - a species adapted to a tropical climate and that is still found in China's southerly Yunnan province.
"They thought North China was controlled by tropical climate at that time," explained Ji Li, from Shaanxi Normal University, who collaborated on the study with colleagues professor Yongjian Hou, professor Yongxiang Li and Jie Zhang.
But later research into China's climate history indicates that 3,000 years ago most parts of North China were still controlled by the warm temperate climate zone, and not the subtropic zone.
This discovery would mean that "the air temperature of North China 3,000 years ago was still not high enough for Elephas to live," said Mr Li.
"The species of the elephants is not only a problem of zoology, but also a problem about global climate change," he added.
Palaeoloxodon was thought to have disappeared from its last stronghold in China just before the Pleistocene-Holocene boundary, around 10,000 years ago.
To investigate whether these mammals continued to live beyond the Pleistocene epoch and into the Holocene (the current geological epoch), the team re-examined fossilised elephant teeth discovered in Holocene layers of rock in North China during the 1900s.
Palaeoloxodon's thick tusks reached 3-4m in length
Earlier scientists had identified these fossils as remains of E. maximus. But Mr Li's team concluded the molars and tusks were more like those of the straight-tusked Palaeoloxodon:
"The tusks of Palaeoloxodon are thicker, stronger and longer than [those of] E. maximus", he explained, whereas E. maximus's tusks are "more incurvate".
The team also examined dozens of ancient elephant-shaped bronze wares from the Xia, Shang and Zhou dynasties (around 4,100-2,300 years ago) after Mr Li noticed the trunks on the ornaments didn't resemble those of E. maximus.
Elephants can either have one or two of "fingers" on the tip of their trunk, used for grasping objects.
The 33 elephant bronzes exhumed from different sites in North China all depicted elephants with two "fingers" on their trunks, while E. maximus (Asian elephant) has just one "finger".
Whether Palaeoloxodon had one or two fingers on its trunk is not known. "However, on the trunk of E. maximus, there cannot be two fingers," writes Mr Li in the study.
The age of these elephant-shaped bronzes supports the researchers' theory that Palaeoloxodon did not become extinct until thousands of years later than thought.
Their findings correlate with other recent paleontological discoveries that further large mammal species, thought to have died out at the end of the Pleistocene, actually lasted in to the Holocene.
These include the woolly rhinoceros (Coelodonta antiquitatis), woolly mammoth (Mammuthus primigenius) and the aurochs (Bos primigenius).
Such discoveries suggest that the extinction period of many Pleistocene land mammals may have lasted longer than was previously thought.
Edited by Taipan, Jul 23 2016, 10:59 PM.
|Ausar||Dec 29 2012, 11:52 AM Post #2|
Deathless Decepticon since '12
|What finally killed of the last Palaeoloxodon?|
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