时间:2018-05-21 编辑:良培 手机版

  For more than fifty years, many evolutionary biologists posited that early fish such as Eusthenopteron developed limbs as a result of the need to drag themselves across short distances when their watery habitats dried up during periods of drought. However, new fossil evidence suggests that this hypothesis is incorrect. Fossilized remains of Acanthostega, a primitive fish, reveal that even though the animal had rudimentary limbs, it could not walk on land. Acanthostega lacked ankles, which means that its limbs couldn’t support its weight; furthermore, its ribs were too short to prevent the organism’s chest cavity from collapsing once the animal left water.

  1. Which of the following would most strengthen the author’s argument?

  A. The fossilized remains of the Acanthostega are the earliest known evidence of early fish.

  B. The modem descendants of Acanthostega are not able to drag themselves across short distances on land.

  C. Biologists have found that some aquatic species can successfully drag themselves across land even though these species do not possess ankles.

  D. Any animal with a collapsed chest cavity is not able to survive long enough to travel even a short distance across land.

  E. Some evolutionary biologists believe that the new fossils are not from Acanthostega.