評論
打印
He named the jaw livoniana and to prove it really was a transitional form
他將這塊顎骨化石命名為“文塔螈”，為了證明它的確是過渡型物種
he ran it through something called a cladistic analysis.
他用所謂的譜系分支分析對它進(jìn)行研究
A computer is programmed with all the anatomical features that distinguish fish from tetrapods.
把能夠區(qū)別魚和四足動物的解剖結(jié)構(gòu)特點(diǎn)輸入電腦
Some are obvious, such as does the specimen have limbs or fins?
其中一些區(qū)別很明顯，比如標(biāo)本是有肢，還是有鰭
Others are tiny shifts in the position of blood vessels or bones.
另一些區(qū)別則很微妙，如血管或骨頭的位置
Such minute details allow scientists to identify a creature from just a fossil fragment
這些微小的細(xì)節(jié)使科學(xué)家們僅用一塊化石碎片就能鑒定這種動物
and place it in an evolutionary tree relative to other animals.
并把它放在進(jìn)化樹上與其它動物關(guān)聯(lián)的位置
For this comparison a lobe-finned fish jaw is on one side,
通過比較，肉鰭魚的顎位于一端
livoniana is in the middle and a Devonian tetrapod jaw is on the other side.
文塔螈處于中間，而泥盆紀(jì)四足動物的顎則位于另一端
What you can see if we look at the end points that these two jaws differ in quite a lot of ways.
如果光看這兩邊的兩塊顎骨，你會發(fā)現(xiàn)它們有很多不同點(diǎn)
First of all if we look at this pit in the fish jaw which is particularly important feature,
首先我們看一下魚顎骨的這個凹陷區(qū)，它是最重要的特征
a deep hollow that goes all the way through to underlying bones.
這個深洞一直通到了下面的骨頭
The bone you get in the bottom there is a different one to what are coming up on the surface here.
這下面的骨頭與上面位于表面的骨頭不是同一塊
In Devonian that's the same place.
這是泥盆紀(jì)顎骨的同一塊區(qū)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，現(xiàn)在環(huán)繞的是一個血管出口，這一點(diǎn)有別于其它顎骨。
