Even the earliest known species

This topic has expert replies
Moderator
Posts: 7187
Joined: Thu Sep 07, 2017 4:43 pm
Followed by:23 members

Even the earliest known species

by BTGmoderatorDC » Fri Dec 08, 2017 10:35 pm
Even the earliest known species of land animals, known from fossils dating from the late Silurian period, 400 million years ago, show highly evolved adaptations to life on land. Since neither aquatic nor amphibious animals exhibit these adaptations, early species of land animals must have evolved very rapidly after leaving an aquatic environment.

Which one of the following is an assumption on which the argument depends?

(A) Known fossils of early land animals include fossils of animals that lived relatively soon after the first emergence of land animals.

(B) Fossils from the late Silurian period represent only a small number of the animal species that were alive at that time.

(C) No plants were established on land before the late Silurian period.

(D) No present-day species of aquatic animal is descended from a species of animal that once lived on land.

(E) All animals alive in the late Silurian period lived either exclusively on land or exclusively in the water.

I am confused in it, isn't the best option E?

OA E
Source: — Critical Reasoning |

User avatar
Master | Next Rank: 500 Posts
Posts: 228
Joined: Thu Apr 20, 2017 1:02 am
Location: Global
Thanked: 32 times
Followed by:3 members
GMAT Score:770

by elias.latour.apex » Mon Dec 11, 2017 5:21 pm
No, I'm pretty sure that (A) is the credited response.

The conclusion talks about evolving quite rapidly. Why would we think that the animals evolved rapidly? Couldn't it have taken them millions of years to do so? Answer choice (A), if negated, indicates that: Known fossils of early land animals include no fossils of animals that lived relatively soon after the first emergence of land animals. If that is true, we have no reason to conclude that the evolution happened rapidly.

I'm curious about these questions you post. What is the source?
Elias Latour
Verbal Specialist @ ApexGMAT
blog.apexgmat.com
+1 (646) 736-7622