Based on real-text corpora with syntactic annotation, this study quantitatively addressed the following two questions: whether quantitative methods and indexes can point to the diachronic syntactic drifts characterizing the evolution from Latin to Romance languages and whether these methods and indexes can provide evidence to evince the shared syntactic features among Romance languages and define them as a distinctive language subgroup. Our study shows that the distributions of dependency directions are suggestive of positive answers to the above two questions. In addition, the dependency syntactic networks extracted from the dependency treebanks reflect the degree of inflectional variation of a language, and the clustering analysis shows that these parameters, in spite of some imperfections, can also help differentiate Romance languages from Latin diachronically and from other languages synchronically.