This paper deals with the evolution of nominal expressions with prenominal possessives in Romance languages. Until now, the prevalent view has been that their historical development follows one of the two diachronic paths: either they stop co-occurring with determiners (French, Spanish) or they start requiring their presence (European Portuguese). One common analysis associates the first case with a transition from a modifier to a determiner semantics of possessives and the second with a retention of a modifier semantics (e.g. Alexiadou 2004). It has also been observed, however, that documented Romance languages each make use of two morphologically distinct possessive paradigms, the so-called short and long forms, and, at least for French, that the short forms co-occur with determiners in historical documents less frequently than the long ones (Butet 2018). We adduce novel quantitative evidence from treebanks of French, Spanish, and Portuguese to the latter observation and show for the first time that the two paradigms followed very different evolutionary trajectories: frequency of determiners goes monotonically up with long possessives and goes up and then down with the short possessives across the three languages. Given these new data, we argue that the only point of evolutionary divergence in Romance possessive DPs is the choice of either the long or the short prenominal possessive in each of the languages, while the semantics of long and short possessives is stable both diachronically and across the three languages we examine. We also argue that the observed diachronic developments are consequences of a pan-Romance rise of a DP grammar. The paper thus contributes to our understanding of the emergence of DP in general and definiteness marking in particular, of the semantico-syntactic architecture of possessive DPs, as well as of the evolutionary divergence and convergence within a language family.