Where does “dotzena” come from?

dotzena (Old Occitan) comes from Old Occitan dotze, from Vulgar Latin dodeci, from Latin duodecim, from Latin decem, from Latin -nus, from Proto-Italic -nos, from Proto-Indo-European -nós — Creates verbal adjectives from roots.

Ancestry of “dotzena”, step by step

Step	Language	Word	Meaning
1	Old Occitan	dotze	—
2	Vulgar Latin	dodeci	—
3	Latin	duodecim	twelve; 12; dozen
4	Latin	decem	ten; 10
5	Latin	-nus	-an
6	Proto-Italic	-nos	Creates verbal adjectives from verb stems
7	Proto-Indo-European	-nós	Creates verbal adjectives from roots

Every word from Proto-Indo-European -nós →Every word from Latin -nus →Every word from Latin decem →