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 北美托福答案 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