How does Romanian preserve more of the Latin case system than other Romance languages?

While the Latin nominal case system has largely disappeared in other modern Romance languages, Romanian preserves a functional case distinction through its use of an inflected article.1

In Romanian, this system allows the language to distinguish between the nominative-accusative (direct) and the genitive-dative (oblique) cases. While other Romance languages typically rely on prepositions to indicate relationships between words—such as using de la in French or della in Italian to denote possession—Romanian employs an inflected form that mirrors the Latin structure. For example, the Latin matris ("the mother's") corresponds to the Romanian mamei, whereas other Romance languages must use additional words to convey the same grammatical meaning.12

Consequently, Romanian maintains a level of morphological inflection that has been replaced by word order or prepositional constructions in most other related languages.1