听力文本

He named the jaw livoniana and to prove it really was a transitional form
他将这块颚骨化石命名为“文塔螈”，为了证明它的确是过渡型物种
he ran it through something called a cladistic analysis.
他用所谓的谱系分支分析对它进行研究
A computer is programmed with all the anatomical features that distinguish fish from tetrapods.
把能够区别鱼和四足动物的解剖结构特点输入电脑
Some are obvious, such as does the specimen have limbs or fins?
其中一些区别很明显，比如标本是有肢，还是有鳍
Others are tiny shifts in the position of blood vessels or bones.
另一些区别则很微妙，如血管或骨头的位置
Such minute details allow scientists to identify a creature from just a fossil fragment
这些微小的细节使科学家们仅用一块化石碎片就能鉴定这种动物
and place it in an evolutionary tree relative to other animals.
并把它放在进化树上与其它动物关联的位置

For this comparison a lobe-finned fish jaw is on one side,
通过比较，肉鳍鱼的颚位于一端
livoniana is in the middle and a Devonian tetrapod jaw is on the other side.
文塔螈处于中间，而泥盆纪四足动物的颚则位于另一端
What you can see if we look at the end points that these two jaws differ in quite a lot of ways.
如果光看这两边的两块颚骨，你会发现它们有很多不同点
First of all if we look at this pit in the fish jaw which is particularly important feature,
首先我们看一下鱼颚骨的这个凹陷区，它是最重要的特征
a deep hollow that goes all the way through to underlying bones.
这个深洞一直通到了下面的骨头
The bone you get in the bottom there is a different one to what are coming up on the surface here.
这下面的骨头与上面位于表面的骨头不是同一块
In Devonian that's the same place.
这是泥盆纪颚骨的同一块区域，
The pit has almost disappeared surrounding now a blood vessel hole here which we wouldn't have in the other jaw.
凹陷基本上消失，现在环绕的是一个血管出口，这一点有别于其它颚骨。

词汇解析

1.distinguish...from... 将…与…区分开
Only doubt can distinguish prophets from maniacs.
唯有怀疑才能区分先知与疯子。

2.in the position of 处在…位置上
Dealers do this when they sense you're undecided, but they want to be in the position of control.
经销商们感到你犹豫不决时就会这样做，不过他们是想占据支配地位。

3.quite a lot of 非常多，相当多
He'd done quite a lot of properties locally and seemed to be working out where our story fitted in.
他通过做这些获得了许多的财产，并且看起来似乎在这之前就有过相同的经验。

视频及简介

19世纪，英国生物学家赫胥黎在研究了尼安德特人的头骨以后，认为是一个具有猿脸的头骨，但决不是人与猿之间的中间缺环。这就告诉我们，人与猿之间的亲缘关系，似乎还应该有一环。1891年发现直立猿人（爪哇猿人）的骨胳，证明这个缺环确实是存在的。可是，日本的人类学家认为爪哇猿人尚不是真正的中间缺环。那么，在猿与人之间到底应该是什么样的一环呢？在埃塞俄比亚发现的早期人科动物化石，很可能是过渡物种。这一发现，弥补了原始人类进化中的一个“缺环”。