南美发现超大海龟化石
文章来源:未知 文章作者:enread 发布时间:2012-05-21 05:41 字体: [ ]  进入论坛
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Picture a turtle the size of a Smart car, with a shell large enough to double as a kiddie(小孩) pool. Paleontologists from North Carolina State University have found just such a specimen1 -- the fossilized remains2 of a 60-million-year-old South American giant that lived in what is now Colombia. The turtle in question is Carbonemys cofrinii, which means "coal turtle," and is part of a group of side-necked turtles known as pelomedusoides. The fossil was named Carbonemys because it was discovered in 2005 in a coal mine that was part of northern Colombia's Cerrejon formation. The specimen's skull3 measures 24 centimeters, roughly the size of a regulation NFL football. The shell which was recovered nearby -- and is believed to belong to the same species -- measures 172 centimeters, or about 5 feet 7 inches, long. That's the same height as Edwin Cadena, the NC State doctoral student who discovered the fossil.

"We had recovered smaller turtle specimens4 from the site. But after spending about four days working on uncovering the shell, I realized that this particular turtle was the biggest anyone had found in this area for this time period -- and it gave us the first evidence of giantism in freshwater turtles," Cadena says.

Smaller relatives of Carbonemys existed alongside dinosaurs5. But the giant version appeared five million years after the dinosaurs vanished, during a period when giant varieties of many different reptiles6 -- including Titanoboa cerrejonensis, the largest snake ever discovered -- lived in this part of South America. Researchers believe that a combination of changes in the ecosystem7, including fewer predators8, a larger habitat area, plentiful9 food supply and climate changes, worked together to allow these giant species to survive. Carbonemys' habitat would have resembled a much warmer modern-day Orinoco or Amazon River delta10.

In addition to the turtle's huge size, the fossil also shows that this particular turtle had massive, powerful jaws11 that would have enabled the omnivore(杂食动物) to eat anything nearby -- from mollusks(软体动物) to smaller turtles or even crocodiles.

Thus far, only one specimen of this size has been recovered. Dr. Dan Ksepka, NC State paleontologist and research associate at the North Carolina Museum of Natural Sciences, believes that this is because a turtle of this size would need a large territory in order to obtain enough food to survive. "It's like having one big snapping turtle living in the middle of a lake," says Ksepka, co-author of the paper describing the find. "That turtle survives because it has eaten all of the major competitors for resources. We found many bite-marked shells at this site that show crocodilians preyed13 on side-necked turtles. None would have bothered an adult Carbonemys, though -- in fact smaller crocs would have been easy prey12 for this behemoth(巨兽,河马) ."

The paleontologists' findings appear in the Journal of Systematic14 Palaeontology. Dr. Carlos Jaramillo from the Smithsonian Tropical Research Institute in Panama and Dr. Jonathan Bloch from the Florida Museum of Natural History contributed to the work. The research was funded by grants from the Smithsonian Institute and the National Science Foundation.



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1 specimen Xvtwm     
n.样本,标本
参考例句:
  • You'll need tweezers to hold up the specimen.你要用镊子来夹这标本。
  • This specimen is richly variegated in colour.这件标本上有很多颜色。
2 remains 1kMzTy     
n.剩余物,残留物;遗体,遗迹
参考例句:
  • He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
  • The remains of the meal were fed to the dog.残羹剩饭喂狗了。
3 skull CETyO     
n.头骨;颅骨
参考例句:
  • The skull bones fuse between the ages of fifteen and twenty-five.头骨在15至25岁之间长合。
  • He fell out of the window and cracked his skull.他从窗子摔了出去,跌裂了颅骨。
4 specimens 91fc365099a256001af897127174fcce     
n.样品( specimen的名词复数 );范例;(化验的)抽样;某种类型的人
参考例句:
  • Astronauts have brought back specimens of rock from the moon. 宇航员从月球带回了岩石标本。
  • The traveler brought back some specimens of the rocks from the mountains. 那位旅行者从山上带回了一些岩石标本。 来自《简明英汉词典》
5 dinosaurs 87f9c39b9e3f358174d58a584c2727b4     
n.恐龙( dinosaur的名词复数 );守旧落伍的人,过时落后的东西
参考例句:
  • The brontosaurus was one of the largest of all dinosaurs. 雷龙是所有恐龙中最大的一种。 来自《简明英汉词典》
  • Dinosaurs have been extinct for millions of years. 恐龙绝种已有几百万年了。 来自《简明英汉词典》
6 reptiles 45053265723f59bd84cf4af2b15def8e     
n.爬行动物,爬虫( reptile的名词复数 )
参考例句:
  • Snakes and crocodiles are both reptiles. 蛇和鳄鱼都是爬行动物。 来自《简明英汉词典》
  • Birds, reptiles and insects come from eggs. 鸟类、爬虫及昆虫是卵生的。 来自《现代汉英综合大词典》
7 ecosystem Wq4xz     
n.生态系统
参考例句:
  • This destroyed the ecosystem of the island.这样破坏了岛上的生态系统。
  • We all have an interest in maintaining the integrity of the ecosystem.维持生态系统的完整是我们共同的利益。
8 predators 48b965855934a5395e409c1112d94f63     
n.食肉动物( predator的名词复数 );奴役他人者(尤指在财务或性关系方面)
参考例句:
  • birds and their earthbound predators 鸟和地面上捕食它们的动物
  • The eyes of predators are highly sensitive to the slightest movement. 捕食性动物的眼睛能感觉到最细小的动静。 来自《简明英汉词典》
9 plentiful r2izH     
adj.富裕的,丰富的
参考例句:
  • Their family has a plentiful harvest this year.他们家今年又丰收了。
  • Rainfall is plentiful in the area.这个地区雨量充足。
10 delta gxvxZ     
n.(流的)角洲
参考例句:
  • He has been to the delta of the Nile.他曾去过尼罗河三角洲。
  • The Nile divides at its mouth and forms a delta.尼罗河在河口分岔,形成了一个三角洲。
11 jaws cq9zZq     
n.口部;嘴
参考例句:
  • The antelope could not escape the crocodile's gaping jaws. 那只羚羊无法从鱷鱼张开的大口中逃脱。
  • The scored jaws of a vise help it bite the work. 台钳上有刻痕的虎钳牙帮助它紧咬住工件。
12 prey g1czH     
n.被掠食者,牺牲者,掠食;v.捕食,掠夺,折磨
参考例句:
  • Stronger animals prey on weaker ones.弱肉强食。
  • The lion was hunting for its prey.狮子在寻找猎物。
13 preyed 30b08738b4df0c75cb8e123ab0b15c0f     
v.掠食( prey的过去式和过去分词 );掠食;折磨;(人)靠欺诈为生
参考例句:
  • Remorse preyed upon his mind. 悔恨使他内心痛苦。 来自《现代英汉综合大词典》
  • He had been unwise and it preyed on his conscience. 他做得不太明智,这一直让他良心不安。 来自辞典例句
14 systematic SqMwo     
adj.有系统的,有计划的,有方法的
参考例句:
  • The way he works isn't very systematic.他的工作不是很有条理。
  • The teacher made a systematic work of teaching.这个教师进行系统的教学工作。
TAG标签: species shell turtle
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