gmatblood wrote:Fossils of the arm of a sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of the Greater Antilles islands.

A. sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of
B. sloth, that they found in Puerto Rico in 1991, has been dated at 34 million years old, thus making it the earliest mammal known on
C. sloth that was found in Puerto Rico in 1991, was dated at 34 million years old, making this the earliest known mammal of
D. sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on
E. sloth which, found in Puerto Rico in 1991, was dated at 34 million years old, made the sloth the earliest known mammal of

IMO:D

I think it is E

A - ... made IT the earliest (it is very far from the subject)
B - sloth, that THEY found (who - they?)
C - FOSSILS of the arm of the sloth... WAS dated (should be plural)
D - HAVE BEEN DATED (the action does not take place till now, should be past)
E - seems correct

Please correct me if I'm wrong!
What is the OA?

IMO: D

Thanks.

Killed A because of singular/plural issue.

Killed B because of ambiguous "they."

Killed C because of ambigouous "this."

Last clause of E sounds awkward.

IMO D.

Fossils of the arm of a sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on the Greater Antilles islands.

Only B and D uses 'on' at the end. so eliminate A C E
B - they doesn't have a clear referent

"Sloth" is the object of the preposition "of." The real subject is "fossils," which is indeed plural.

does "mammal of" and "mammal on" make any difference here?

Fossils of the arm of a sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of the Greater Antilles islands.

A. sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of
B. sloth, that they found in Puerto Rico in 1991, has been dated at 34 million years old, thus making it the earliest mammal known on
C. sloth that was found in Puerto Rico in 1991, was dated at 34 million years old, making this the earliest known mammal of
D. sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on
E. sloth which, found in Puerto Rico in 1991, was dated at 34 million years old, made the sloth the earliest known mammal of

This question has been discussed before. I wanted to know if mammal on and mammal of made any difference?

nidhis.1408 wrote:Fossils of the arm of a sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of the Greater Antilles islands.

A. sloth found in Puerto Rico in 1991, and dated at 34 million years old, made it the earliest known mammal of
B. sloth, that they found in Puerto Rico in 1991, has been dated at 34 million years old, thus making it the earliest mammal known on
C. sloth that was found in Puerto Rico in 1991, was dated at 34 million years old, making this the earliest known mammal of
D. sloth, found in Puerto Rico in 1991, have been dated at 34 million years old, making the sloth the earliest known mammal on
E. sloth which, found in Puerto Rico in 1991, was dated at 34 million years old, made the sloth the earliest known mammal of

This question has been discussed before. I wanted to know if mammal on and mammal of made any difference?

It depends on whether you want to emphasize the mammal's presence on the Islands or its provenance from the Islands. The difference is slight but "on" makes more sense if you think about it (i.e., it is unlikely that the sloth originated on the Islands).