Eighty million years ago, dinosaurs ruled the earth.
八千万年前，地球是恐龙的天下。
South America and Africa separated 200 million years ago.
南美洲和非洲于2亿年前分离。
South America separated from Africa 200 million years ago.
2亿年前南美洲和非洲分离。
The age of the earth is reckoned at about 4 600 million years.
估计地球的年龄大约为46亿年。
Twenty million years ago, Idaho was populated by dense primordial forest.
两千万年前，爱达荷州遍布着茂密的原始森林。
The most ancient parts of the continental crust are 4000 million years old.
该大陆地壳最古老的那些部分有40亿年了。
It has been suggested that mammals took over from dinosaurs 65 million years ago.
有人提出哺乳动物是在6 500万年前取代恐龙的。
Twenty million years ago, Idaho was not the arid place it is now. Rather, it was warm and damp, populated by dense primordial forest.
2000万年前，爱达荷州不像现在这样干旱。确切地说，它那时温暖潮湿，生长着茂密的原始森林。
In geological time, a million years is recent history.
在地质时代，一百万年属于近代史。
Ants were farmers fifty million years before humans were.
蚂蚁比人类早五千万年成为农民。
A million years ago, we were essentially an endangered species.
一百万年前，我们基本上是濒临灭绝的物种。
It is said that dinosaurs were living in 200 million years ago.
据说恐龙是生存在200万年前。
For seven million years they lived on the planet as part of nature.
七百万年来，他们作为大自然的一部分在这个星球上生活。
It must be really old, about 4 billion years, give or take a few hundred million years.
它一定非常古老，大约有40亿年，有几亿年的误差。
Wild carrots probably evolved with the other flowering plants about 360 million years ago.
在大约3.6亿年前，野生胡萝卜也许是和其它开花植物一起进化的。
These calculations suggest that a period of about one million years would have been required.
这些计算表明，这个过程可能需要大约一百万年的时间。
The early human skeleton reconstruction "Lucy" dating back 3.2 million years debuted yesterday.
昨天，追溯到320万年前的原始人骨架重建“露西”首次亮相。
Ant societies existed in something like their present form more than seventy million years ago.
蚂蚁社会大约在七千万年前就以类似现在的形式存在。
For reasons not fully understood, the field itself reverses periodically every million years or so.
由于一些尚不完全清楚的原因，该领域本身大约每隔百万年就会周期性地翻转一次。
Whales originated in the freshwater lakes and rivers of ancient Asia about sixty million years ago.
鲸鱼起源于大约六千万年前亚洲的淡水湖泊和河流。
Indeed, unaltered shells of marine invertebrates are known from deposits over 100 million years old.
事实上，海洋无脊椎动物不变的外壳是通过1亿年前的沉积物发现的。
In some parts of the world you can still find tools that people used more than two million years ago.
在世界的某些地方，你仍然可以找到两百多万年前人们使用的工具。
Over the past two million years, colder glacial periods have alternated with warmer interglacial periods.
在过去的200万年里，寒冷的冰期与较暖和的间冰期交替出现。
This gigantic boa constrictor, like a snake, lived 60 million years ago in what is now northern Colombia.
6千万年前，这种类似于蟒的巨蛇生活在现在的哥伦比亚北部。
The researchers found that venom evolved before snakes even existed, about a hundred million years before.
研究人员发现毒液甚至在蛇出现之前就已经进化出来了，大约在一亿年前。
We knew that it was formed from sandstone that solidified somewhere between 150 and 300 million years ago.
我们知道它是由1.5亿到3亿年前在某地固化的砂岩形成的。
For today, let's look at a reptile, a predator that hasn't evolved much in the last seventy million years.
今天，让我们来看看一种爬行动物，一种在过去七千万年里没有进化很多的食肉动物。
About 160 million years ago, a female pterosaur with an injured wing dropped from the sky into a watery grave.
约一亿六千万年前，一只雌性翼龙隐翅膀受伤而坠落，葬身水底。
Human beings used stone chips for more than two million years, but human life changed very little in that time.
人类使用石屑超过二百万年，但在那段时间里，人类的生活几乎没有改变。
It will take me a million years to explain even just the basics of this movement as precession is quite complex.
哪怕是这个运动的基本原理，我也要花一百万年才能解释清楚，因为旋进是相当复杂的。
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