GWD 27-22

Q22:

Whales originated in the freshwater lakes and rivers of ancient Asia about sixty million years ago.  Not until about ten million years later did species of whales develop specialized kidneys enabling them to drink salt water.  Although fossil evidence shows that some early whale species that lacked such kidneys sometimes swam in the Earth’s saltwater oceans, these species must have had to return frequently to freshwater rivers to drink.

Which of the following is most strongly supported by the information given?

1. Fossils of whale species dating from between sixty million and fifty million years ago will not be found on continents that were at the time separated from ancient Asia by wide expanses of ocean.

2. Among whale fossils that date from later than about fifty million years ago, none are fossils of whale species that drank only fresh water.

3. Fossils of whale species that drank fresh water will not be found in close proximity to fossils of whale species that drank salt water.

4. The earliest whales that drank salt water differed from fresh-water-drinking whales only in their possession of specialized kidneys.

     E Between sixty million and fifty million years ago, the freshwater lakes and rivers in which whales originated were     gradually invaded by salt water

答案是 A , 我觉得C , 对A 不是很理解, 是不是说,那块陆地是因为海洋扩展造成的, 也就是说那块地靠海, 所以就不会有淡水鲸鱼了, 我的理解对嘛? 那C 为什么错, 难道有些地方是淡水的会变成海水,所有可能有两种鲸鱼的化石?

LZ没读懂题目意思吧。 A中是讲50-60million years ago的化石不可能存在于被大海隔离的ancient asia之外的地方。因为他们不可以喝海水，游不过去。

C错，在哪个进化的过程中，应该有两种不同的whale同时存在的。淡水和海水并不是两个不可并存的概念，试想一下入海口和沿海。

只要把年代搞清出就好

60M年前，金鱼从淡水里形成

10m语前，金鱼开始可以进入海水里了

但是呢，早先有些没有适应海水器官的金鱼也seldom去海里游，但他们常常会回到淡水

那C肯定不能得出来，因为既然有鱼海里游游，淡水里游游，那化石发现在一起是很正常的事

A：sixty million and fifty million years ago不可能有金鱼出现在被海水环绕的大陆上，因为那时候金鱼还未完全形成，金鱼要在60m年前才在ASIA 大陆上形成。所以之前是不会有金鱼在那块被分开的陆地上的。

哦. 又是阅读的问题, 多谢你们的解释,很明了了

虫哥...

答案应该是E吧.

A,被大海割开的大陆就没有淡水么? 日本岛呢?

E 的意思是鲸鱼生存的淡水被海水侵蚀,所以逐渐导致了鲸鱼进行盐水适应性的演变啊!

大家再讨论讨论吧!

A is right answer. The conclusion is that whale kidney developed to be able to drink salty water between the time period. A is a scenario where no whale, without the specialized kidney, did not exist on continents other than Asia from which the whale is originated.

A->B and (no B, no A) are logically consistent, hence strengthening the argument.