Gerund verbs generate root clauses in Old Romanian (OR), but not in Modern Romanian (MR). We argue that the root clause phenomenon arises from the presence of a null Assertion Operator in OR, which has been lost in MR. This Operator originates from the mapping of discourse features to syntax, but involves a marked option for feature checking (i.e., pragmatic versus syntactic), so it is easier for it to disappear in the process of language acquisition.