巴基鲸可能是通过像陆地哺乳动物一样的耳朵的开口来探测声音。
Pakicetus probably detected sound through the ear opening as in land mammals.
直到最近才发现的化石，显然是介于陆地哺乳动物和鲸类之间的过渡物种。
Missing until recently were fossils clearly intermediate, or transitional, between land mammals and cetaceans.
叉角羚与羚羊虽无亲缘关系，但却形似羚羊，它是新大陆速度最快的陆地哺乳动物。
The pronghorn, which resembles an antelope, though they are unrelated, is the fastest land mammal of the New World.
受到威胁的陆地哺乳动物主要集中在亚洲南部和东南亚地区。
Threatened land mammals are concentrated in south and south-east Asia.
长颈鹿是世界上最高的陆地哺乳动物，可以高达20英尺。
Giraffes are the tallest land mammals in the world, with heads that may tower 20 feet above ground.
由于气候的恶劣，格陵兰岛的陆地哺乳动物的数量是很有限的。
Because of the harsh climate, the number of Greenlandic terrestrial mammals is very limited.
但繁衍迟钝的陆地哺乳动物却因为有了同心专心只想满意一已私欲的人类而濒临。
But the slow-breeding mammals of the sea have been all but wiped out by humans seeking to satisfy their wants and whims.
在《物种起源》中，达尔文猜测了自然选择使陆地哺乳动物进化成鲸鱼的可能过程。
In "The Origin of Species," Darwin speculated on how natural selection could turn a land mammal into a whale.
大多数鸟、陆地哺乳动物、植物、树木和灌木丛的后代，正与此时陆地的振动相匹配。
Most subsequent generations of birds, land mammals, plants, trees and shrubs are matching the vibration of the land at this time.
加拿大科学家声称发现一个化石，这有助于帮助揭秘海豹如何从陆地哺乳动物进化而来。
Scientists in Canada say a fossil they found helps to understand how seals developed from land-based mammals.
对于某些人来说，冰河世纪毛犀牛的拱鼻和角并不意味着这种大型陆地哺乳动物，却是巨型鸟类的喙和爪。
To some, the arched snout and horns of skeletal Ice Age woolly rhinoceroses suggested not a vast land mammal, but the beak and claws of a giant bird.
例如，陆地哺乳动物如何回到水中，进化成鲸鱼、海豹和海牛呢？这一问题一直让Fish和他的同事困惑不解。
For instance, how terrestrial mammals moved back into the water and evolved into whales, seals and manatees continues to puzzle Fish and colleagues.
在陆地哺乳动物中，北极熊无疑是长距离游泳冠军。人们经常在距离陆地或者大块浮冰50英里远的地方看到它们。
Polar bears are champion long-distance swimmers among land mammals, and it is not uncommon to find them at sea as far as 50 miles from land or an ice floe.
南极是许多种海豹的栖息之地，就像这只毛皮海豹，它的大眼睛是用来在黑暗的海水中追寻猎物的，与陆地哺乳动物的眼睛形状稍有不同。
Antarctica is home to many seal species such as this fur seal. Its large eyes are designed to seek out prey in dim waters and are a slightly different shape to a land mammal's.
一项对全球野生动物的大规模年度调查表明，近四分之一的陆地哺乳动物物种濒临灭绝，还有许多其余的物种，甚至在科学界知道它们之前可能就已经绝迹了。
Nearly a quarter of the world's land mammal species are at risk of extinction, and many others may vanish before they are even known to science, according to a major annual survey of global wildlife.
对我们人类以及其他的陆地哺乳动物来说，有些感官是与生俱来的，然而对于鲸鱼来讲，这些功能要么已经衰退或彻底消失，要么就无法在水中正常发挥作用。
Some of the senses that we and other terrestrial mammals take for granted are either reduced or absent in cetaceans or fail to function well in water.
因此，你可能会想，现代陆龟可能从早期的陆栖时代就一直呆在陆地上，就像大多数哺乳动物，他们中的一些返回海洋之后所做的那样。
You might think, therefore, that modem land tortoises have probably stayed on land ever since those early terrestrial times, as most mammals did after a few of them went back to the sea.
大多数哺乳动物生活在陆地上。
许多原始生物灭绝，鲨鱼和硬骨鱼成为水域的主人，四足动物最终进化成了恐龙和哺乳动物，征服了陆地。
Many primitive lineages went extinct as sharks and bony fish became masters of the waters and tetrapods, the four-legged animals that eventually evolved into dinosaurs and mammals, conquered the land.
在陆地和海洋，人类都已处在巨大的生物金字塔的最顶端，成为所有生物的主宰，并给海洋哺乳动物带来巨大的危胁。
At sea, as on land, humans have now positioned themselves on the top of the whole great pyramid of life, and they have caused serious problems for the mammals of the sea.
我们也许还在津津乐道于恐龙时代或哺乳动物时代，但殊不知第一只动物爬上陆地时，昆虫的时代也已然来临。
We talk about the age of dinosaurs or the age of mammals, but since the first animal climbed onto land, every age has been, by any reasonable measure, the age of insects too.
在面积宽阔的陆地上，体型大的哺乳动物生存地最好，因为和体积小的动物相比，他们更少受寒冷伤害，被食肉动物袭击的机率也小。
On large expanses of land, big animals do best, because they are less vulnerable to cold and less likely to be attacked by predators.
但是，由于在陆地上不需要这样的电子磁场探测系统，爬行类动物，鸟类和哺乳动物都渐渐失去了这一功能。
However, over the years reptiles, birds and mammals lost their electrosense as it wasn’t needed for life on terra firma.
我通过看书知道大多数哺乳动物都生活在陆地上。
小型哺乳动物和土壤动物是陆地生态系统食物链中重要环节，在生物指示研究中具有十分重要的作用。
Small mammals and soil animals are key links of trophic chains in terrestrial eco-systems, and play very important roles in bio-indicative studies.
当然我们和另外一些陆地上的哺乳动物的一些器官或减少，或与鲸鱼不同，或丢失在水中很好生存的功能。
Some of the senses that we and other terrestrial mammals take for granted are either reduced or absent in cetaceans or fail to function well in water.
当然我们和另外一些陆地上的哺乳动物的一些器官或减少，或与鲸鱼不同，或丢失在水中很好生存的功能。
Some of the senses that we and other terrestrial mammals take for granted are either reduced or absent in cetaceans or fail to function well in water.
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