The idea of cloning extinct life forms still belongs to science fiction.
对绝种的生命形式进行克隆的想法仍然属于科学幻想。
Scientists are attempting to compare features of extinct animals with living analogues.
科学家正试图把已灭绝动物的特征与现存类似动物相比较。
At the current rate of decline, many of the rain forest animals could become extinct in less than 10 years.
按照目前的下降速度，许多雨林动物不到十年就会绝种。
The simulated mammoths were extinct within decades.
这些模拟的猛犸象群在几十年间便灭绝了。
There's always some guesswork when studying extinct animals.
在研究灭绝的动物时，总要做一些猜测。
As is known to all, the panda is in danger of becoming extinct.
众所周知，熊猫濒临灭绝。
We must protect these endangered animals before they become extinct.
在这些濒危动物灭绝之前，我们必须保护它们。
Unless tiger hunting decreases, tigers will soon be extinct in the wild.
除非减少对老虎的捕猎，否则野生老虎将很快灭绝。
They will tum out to be the second-largest species of birds to become extinct.
它们将成为第二大灭绝的鸟类。
When a species goes extinct, it dramatically changes the landscape of biodiversity.
当一个物种灭绝时，它会极大地改变生物多样性的状况。
Perhaps dinosaurs could not tolerate these extreme temperature changes and became extinct.
也许恐龙无法忍受这些极端的温度变化于是灭绝了。
Whatever the cause, dinosaurs, as well as about half of all species on the planet, went extinct.
不管什么原因，恐龙以及地球上几乎半数以上的物种灭绝了。
The Burgess Shale formation also has fossils of many extinct representatives of modern animal groups.
伯吉斯页岩地层中也有许多代表着现代动物群中已经灭绝的物种的化石。
If these great cats become extinct, the smaller animals they prey upon will overpopulate the forests.
如果这些大型猫科动物灭绝了，那么它们捕食的小型动物将会使森林中物种的密度过高。
Boundary clay layers are used by scientists to determine the rate at which an extinct species declined.
边界粘土层被科学家用来确定一个灭绝物种衰落的速度。
America's national symbol, the bald eagle, almost went extinct twenty years ago, but it has made a comeback.
美国的国家象征秃头鹰在20年前几乎都灭绝了，但它的数量最终有所恢复。
Humans have an obligation to try to save endangered animals, because it is our fault that they are going extinct.
人类有义务去拯救濒临灭绝的动物，因为它们的灭绝是我们的过错。
Cases in which many species become extinct within a geologically short interval of time are called mass extinctions.
许多物种在地质上很短的时间间隔内灭绝的情况称为大灭绝。
With all that attention paid to them, you'd think these creatures would at least have the gratitude not to go extinct.
人们对这些生物如此关注，你可能会想，它们没有灭绝至少应该心存感激。
Thanks to natural selection, most species that have ever lived has already gone extinct, so this is not a new phenomenon.
由于自然选择，大多数曾经存在过的物种已经灭绝，所以这不是一个新现象。
This break in Earth's history is marked by a mass extinction, when as many as half the species on the planet became extinct.
地球历史上的这次重大灾难以物种的大量消亡为标志；当时，地球上多达一半的物种都灭绝了。
Meteorite impacts can be advantageous for some species, which thrive, and disastrous for other species, which become extinct.
陨石的撞击对某些物种是有利的，它们会茁壮成长；而对其他物种则是灾难性的，它们会灭绝。
This was a landscape where antelope of all kinds abounded—along with Bos primigenius, a kind of oxen that has become extinct.
这是一片充满了各种羚羊的土地——还有原牛，一种已经灭绝的牛。
The beavers were hunted a lot, overhunted, they are almost extinct by the 1800s, that meant fewer wetlands, less standing water.
海狸被大量捕杀、过度捕杀，到19世纪它们几乎灭绝了，这意味着湿地和静水变得更少了。
Indeed, most analysts believe that some kind of environmental degradation underlies the demise of many extinct salmon populations.
事实上，大多数分析家认为某种环境退化是许多已灭绝鲑鱼种群消亡的根源。
When prehistoric man arrived in new parts of the world, something strange happened to the large animals: they suddenly became extinct.
当史前人类来到一处新地方时，一些奇怪的事情发生在大型动物身上，那就是它们突然灭绝了。
Geigl and her colleagues looked at 3200-year-old fossil bones belonging to a single individual of an extinct cattle species called an aurochs.
盖格尔和她的同事们研究了3200年前的骨头化石，这些骨头属于一种已经灭绝的叫做欧洲野牛的种类。
Even if the new population is of a different species, it can approximately fill the niche vacated by the extinct population and keep the food web intact.
即使新的种群属于不同物种，它也可以大致填补已灭绝种群空出的生态位，保持食物网的完整。
Other features, however, show experts that Pakicetus is a transitional form between a group of extinct flesh-eating mammals, the mesonychids, and cetaceans.
然而，专家认为巴基鲸是已经灭绝的食肉哺乳动物中爪类和鲸类之间的过渡物种。
Gause performed numerous tow-species experiments in the laboratory, in which one of the species became extinct when only a single kind of resource was available.
高斯在实验室里进行了许多双物种实验，其中一个物种在只有一种单一资源的情况下就灭绝了。
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