蛇类的祖先长什么样
文章来源:未知 文章作者:enread 发布时间:2015-05-22 06:47 字体: [ ]  进入论坛
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The original snake ancestor was a nocturnal, stealth-hunting predator1 that had tiny hindlimbs with ankles and toes, according to research published in the open access journal BMC Evolutionary2 Biology. The study, led by Yale University, USA, analyzed3 fossils, genes4, and anatomy5 from 73 snake and lizard6 species, and suggests that snakes first evolved on land, not in the sea, which contributes to a longstanding debate. They most likely originated in the warm, forested ecosystems7 of the Southern Hemisphere around 128 million years ago.
 
Snakes show incredible diversity, with over 3,400 living species found in a wide range of habitats, such as land, water and in trees. But little is known about where and when they evolved, and how their original ancestor looked and behaved.
 
Lead author Allison Hsiang said: "While snake origins have been debated for a long time, this is the first time these hypotheses have been tested thoroughly8 using cutting-edge methods. By analyzing9 the genes, fossils and anatomy of 73 different snake and lizard species, both living and extinct, we've managed to generate the first comprehensive reconstruction10 of what the ancestral snake was like."
 
By identifying similarities and differences between species, the team constructed a large family tree and illustrated11 the major characteristics that have played out throughout snake evolutionary history.
 
Their results suggest that snakes originated on land, rather than in water, during the middle Early Cretaceous period (around 128.5 million years ago), and most likely came from the ancient supercontinent of Laurasia. This period coincides with the rapid appearance of many species of mammals and birds on Earth.


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1 predator 11vza     
n.捕食其它动物的动物;捕食者
参考例句:
  • The final part of this chapter was devoted to a brief summary of predator species.本章最后部分简要总结了食肉动物。
  • Komodo dragon is the largest living lizard and a fearsome predator.科摩多龙是目前存在的最大蜥蜴,它是一种令人恐惧的捕食性动物。
2 evolutionary Ctqz7m     
adj.进化的;演化的,演变的;[生]进化论的
参考例句:
  • Life has its own evolutionary process.生命有其自身的进化过程。
  • These are fascinating questions to be resolved by the evolutionary studies of plants.这些十分吸引人的问题将在研究植物进化过程中得以解决。
3 analyzed 483f1acae53789fbee273a644fdcda80     
v.分析( analyze的过去式和过去分词 );分解;解释;对…进行心理分析
参考例句:
  • The doctors analyzed the blood sample for anemia. 医生们分析了贫血的血样。 来自《简明英汉词典》
  • The young man did not analyze the process of his captivation and enrapturement, for love to him was a mystery and could not be analyzed. 这年轻人没有分析自己蛊惑著迷的过程,因为对他来说,爱是个不可分析的迷。 来自《简明英汉词典》
4 genes 01914f8eac35d7e14afa065217edd8c0     
n.基因( gene的名词复数 )
参考例句:
  • You have good genes from your parents, so you should live a long time. 你从父母那儿获得优良的基因,所以能够活得很长。 来自《简明英汉词典》
  • Differences will help to reveal the functions of the genes. 它们间的差异将会帮助我们揭开基因多种功能。 来自英汉非文学 - 生命科学 - 生物技术的世纪
5 anatomy Cwgzh     
n.解剖学,解剖;功能,结构,组织
参考例句:
  • He found out a great deal about the anatomy of animals.在动物解剖学方面,他有过许多发现。
  • The hurricane's anatomy was powerful and complex.对飓风的剖析是一项庞大而复杂的工作。
6 lizard P0Ex0     
n.蜥蜴,壁虎
参考例句:
  • A chameleon is a kind of lizard.变色龙是一种蜥蜴。
  • The lizard darted out its tongue at the insect.蜥蜴伸出舌头去吃小昆虫。
7 ecosystems 94cb0e40a815bea1157ac8aab9a5380d     
n.生态系统( ecosystem的名词复数 )
参考例句:
  • There are highly sensitive and delicately balanced ecosystems in the forest. 森林里有高度敏感、灵敏平衡的各种生态系统。 来自《简明英汉词典》
  • Madagascar's ecosystems range from rainforest to semi-desert. 马达加斯加生态系统类型多样,从雨林到半荒漠等不一而足。 来自辞典例句
8 thoroughly sgmz0J     
adv.完全地,彻底地,十足地
参考例句:
  • The soil must be thoroughly turned over before planting.一定要先把土地深翻一遍再下种。
  • The soldiers have been thoroughly instructed in the care of their weapons.士兵们都系统地接受过保护武器的训练。
9 analyzing be408cc8d92ec310bb6260bc127c162b     
v.分析;分析( analyze的现在分词 );分解;解释;对…进行心理分析n.分析
参考例句:
  • Analyzing the date of some socialist countries presents even greater problem s. 分析某些社会主义国家的统计数据,暴露出的问题甚至更大。 来自辞典例句
  • He undoubtedly was not far off the mark in analyzing its predictions. 当然,他对其预测所作的分析倒也八九不离十。 来自辞典例句
10 reconstruction 3U6xb     
n.重建,再现,复原
参考例句:
  • The country faces a huge task of national reconstruction following the war.战后,该国面临着重建家园的艰巨任务。
  • In the period of reconstruction,technique decides everything.在重建时期,技术决定一切。
11 illustrated 2a891807ad5907f0499171bb879a36aa     
adj. 有插图的,列举的 动词illustrate的过去式和过去分词
参考例句:
  • His lecture was illustrated with slides taken during the expedition. 他在讲演中使用了探险时拍摄到的幻灯片。
  • The manufacturing Methods: Will be illustrated in the next chapter. 制作方法将在下一章说明。
TAG标签: species genes snake
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