Pronoun reference to a noun in a prepositional phrase

[mikrodj]

Hi everyone,
I have a question regarding the use of the pronouns. In the problem 78 in the sentence correction section of the OG 12th, the pronoun it refers to a noun that is in a prepositional phrase. Here is the complete sentence

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

My question is whether this is a rule you can always apply; Thus you cannot use pronouns to refer to an object in a prepositional phrase.
Then a sentence such as:

The pile of plates fell off the table;many of them were broken.

Can them refer to plates here?

If the official sentence were

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

Would it be correct?

Thanks in advance.

[RonPurewal]

My question is whether this is a rule you can always apply; Thus you cannot use pronouns to refer to an object in a prepositional phrase.
Then a sentence such as:

The pile of plates fell off the table;many of them were broken.

i've seen instances in which pronouns can clearly refer to objects of prepositions. however, in all of those cases, the pronouns themselves were ALSO objects of prepositions - so they were PARALLEL to the referent nouns.

your sentence (about plates) should actually be fine, as "them" (object of the second prep "of") is clearly parallel to "plates" (object of the first prep "of"). moreover, it's 100% unambiguous, as there are no other plural nouns in the sentence.

however, i would be extremely suspicious of choices in which a NONPARALLEL pronoun tries to refer to such a noun.

If the official sentence were

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

Would it be correct?

Thanks in advance.

i would say "no", since you don't have the type of parallelism that i mentioned above.

in any case, pronoun ambiguity is a very fuzzy principle, on which the OG writers seem to go back and forth a lot. so you should try to eliminate on other principles first, and only use pronoun ambiguity if it's the ONLY thing you can see.

[mikrodj]

Thank you very much for your explanation.

[Ben Ku]

Glad that helped.

[mikrodj]

Just for the record. I found a correct answer choice in GMAT prep, in which the pronoun it refers to a noun in a prepositional phrase

It was only after Katharine Graham became publisher of The Washington Post in 1963 that it moved into the first rank of American newspapers, and it was under her command that the paper won high praise for its unrelenting reporting of the Watergate scandal.