A group of paleontologists recently announced that a site in Utah has yielded fossils of some of the biggest armored dinosaurs ever found, and that they were at least 25 million years older than any similar dinosaur type previously found in North America.

A) Same
B) and they are at least 25 million years older than those of any similar dinosaur type that previously was
C) and the fossils are at least 25 million years older than any similar dinosaur types that previously were
D) fossils that are at least 25 million years older than those of any similar dinosaur type previously
E) fossils at least 25 million years older than similar dinosaur types previously

I put C. Why is D correct?

Howdy. In the future, please provide an exact citation for the source of a problem (book/website, problem number, etc.) so we can categorize the threads.

In this question, two "splits" provide insight into the grammatical issues under consideration. First, the original sentence and answer choice B use the ambiguous pronoun "they," which can refer either to fossils (correctly) or to paleontologists or dinosaurs (incorrectly). Once choices A and B are eliminated, the remaining choices test parallel structure by focusing on similar comparison terms. Answer choices C and E incorrectly compare fossils to dinosaur types; however, the sentence must compare fossils to fossils rather than fossils to dinosaurs. Answer choice D, the credited answer, corrects this comparison by including the pronoun those to explicitly refer to fossils.

Hope that makes sense!
-dan

Great explanation. Thanks!

Dan was nice enough to answer this without a source but, in future, please cite the source. Officially, we don't answer test questions unless / until the source is cited. Thanks!

If it still matters (I'd searched your forums, and found this answer - excellent by the way, thank you v much!), this was from the GMATPrep Practice Test 2.

I'd gotten it too, and had thought the answer was D as well...

thank you Dan!

Thanks!