The hypothesis
has been advanced that
the ancestors of
such plants and animals as the giant sequoia, the alligator, and the horse
appeared on the fringes of the Arctic Ocean millions of years before lower latitudes.
- before can either act as a preposition followed by a noun or a conjunction followed by a clause.
(A) before lower latitudes : grammar is correct, comparison is incorrect. [appeared on the fringes of the Arctic Ocean millions of years compared to lower altitudes]
(B) before at lower latitudes [incorrect grammer, above explanation]
(C) before they did it at lower latitudes [ it has no pronoun anticident]
(D) before they appeared at lower latitudes : [appeared on the fringes of the Arctic Ocean millions of years compared to they appeared at lower latitudes]
(E) preceding their appearance at lower latitudes [meaning of sentence changed. and in correct modifier]