The Romance plural isogloss and linguistic change: A comparative study of Romance nouns

• Romance noun structures share a unique set of functional categories.
• Parameters on the structure of the noun account for cross-linguistic diversity.
• I argue that Italian plural -i derives from Latin accusative plural -s.

Romance nouns show a well-known morphological isogloss. There are two groups of languages: those pluralizing by suffixing -s (such as Spanish), and those pluralizing by changing the quality of the final vowel (such as Italian). In this paper, I propose an explanation of this isogloss. More precisely, I argue that the cross-linguistic diversity within Romance depends on morpho-phonological parameters on the structure of the noun. These parameters consist of language-particular restrictions on the form of the (nominal) roots and the exponents of gender and number.