科学家首次发现怀孕蜥蜴化石
文章来源:未知 文章作者:enread 发布时间:2011-07-21 07:26 字体: [ ]  进入论坛
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A 120-million-year-old fossil is the oldest pregnant lizard1 ever discovered, according to scientists.

根据科学家研究显示,一具有1.2亿年历史的化石是迄今发现的最古老的怀孕蜥蜴化石。

The lizard was just days from giving birth when it died and was buried
The lizard was just days from giving birth when it died and was buried
The fossil, found in China, is a very complete 30cm (12in) lizard with more than a dozen embryos2 in its body.

Researchers from University College London, who studied the fossil, say it was just days from giving birth when it died and was buried during the Cretaceous period.

The team reports the findings in the journal Naturwissenschaften.

The fossil is especially interesting to scientists because it is a reptile3(爬行动物) that produced live young rather than laying eggs.

Only 20% of living lizards4 and snakes produce live young, and this shows it is an ancient, if unusual, trait.

"I didn't think much of the fossil when I first saw it," said Prof Susan Evans, joint5 lead author of the paper, from University College London.

But when her colleague, Yuan Wang, from the Chinese Academy of Sciences, examined the fossil he spotted6 the tiny remains7 of at least 15 almost fully8 developed embryos inside it.

"Sure enough, when I examined it under the microscope, I could see all these little babies," Prof Evans recalled.

The fossil is so well preserved that the minuscule9(极小的) teeth of the developing young are visible on very close inspection10.

"This specimen11 is the oldest pregnant lizard we have seen," said Prof Evans.

"It implies physiological12 adaptations, like adequate blood supply to the embryos and very thin shells - or no shells at all - to allow oxygen supply, evolved very early on."

Up until now the fossil records only contained examples of marine13 lizards giving birth to live young.

Scientists thought that, in extinct reptiles14, live birth was restricted to aquatic15(水生的) species, such as marine ichthyosaurs(亲戚,相关物) . These creatures would have been able to move through water with relative ease, even when heavily pregnant.



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1 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。
2 embryos 0e62a67414ef42288b74539e591aa30a     
n.晶胚;胚,胚胎( embryo的名词复数 )
参考例句:
  • Somatic cells of angiosperms enter a regenerative phase and behave like embryos. 被子植物体细胞进入一个生殖阶段,而且其行为象胚。 来自辞典例句
  • Evolution can explain why human embryos look like gilled fishes. 进化论能够解释为什么人类的胚胎看起来象除去了内脏的鱼一样。 来自辞典例句
3 reptile xBiz7     
n.爬行动物;两栖动物
参考例句:
  • The frog is not a true reptile.青蛙并非真正的爬行动物。
  • So you should not be surprised to see someone keep a reptile as a pet.所以,你不必惊奇有人养了一只爬行动物作为宠物。
4 lizards 9e3fa64f20794483b9c33d06297dcbfb     
n.蜥蜴( lizard的名词复数 )
参考例句:
  • Nothing lives in Pompeii except crickets and beetles and lizards. 在庞培城里除了蟋蟀、甲壳虫和蜥蜴外,没有别的生物。 来自辞典例句
  • Can lizards reproduce their tails? 蜥蜴的尾巴断了以后能再生吗? 来自辞典例句
5 joint m3lx4     
adj.联合的,共同的;n.关节,接合处;v.连接,贴合
参考例句:
  • I had a bad fall,which put my shoulder out of joint.我重重地摔了一跤,肩膀脫臼了。
  • We wrote a letter in joint names.我们联名写了封信。
6 spotted 7FEyj     
adj.有斑点的,斑纹的,弄污了的
参考例句:
  • The milkman selected the spotted cows,from among a herd of two hundred.牛奶商从一群200头牛中选出有斑点的牛。
  • Sam's shop stocks short spotted socks.山姆的商店屯积了有斑点的短袜。
7 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。
8 fully Gfuzd     
adv.完全地,全部地,彻底地;充分地
参考例句:
  • The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气,然后全部呼出。
  • They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。
9 minuscule V76zS     
adj.非常小的;极不重要的
参考例句:
  • The human race only a minuscule portion of the earth's history.人类只有占有极小部分地球历史。
  • As things stand,Hong Kong's renminbi banking system is minuscule.就目前的情况而言,香港的人民币银行体系可谓微不足道。
10 inspection y6TxG     
n.检查,审查,检阅
参考例句:
  • On random inspection the meat was found to be bad.经抽查,发现肉变质了。
  • The soldiers lined up for their daily inspection by their officers.士兵们列队接受军官的日常检阅。
11 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。
12 physiological aAvyK     
adj.生理学的,生理学上的
参考例句:
  • He bought a physiological book.他买了一本生理学方面的书。
  • Every individual has a physiological requirement for each nutrient.每个人对每种营养成分都有一种生理上的需要。
13 marine 77Izo     
adj.海的;海生的;航海的;海事的;n.水兵
参考例句:
  • Marine creatures are those which live in the sea. 海洋生物是生存在海里的生物。
  • When the war broke out,he volunteered for the Marine Corps.战争爆发时,他自愿参加了海军陆战队。
14 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》
15 aquatic mvXzk     
adj.水生的,水栖的
参考例句:
  • Aquatic sports include swimming and rowing.水上运动包括游泳和划船。
  • We visited an aquatic city in Italy.我们在意大利访问过一个水上城市。
TAG标签: fossil scientists lizard
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