Where does “oscitaturus” come from?

oscitaturus (Latin) comes from Latin ōscitō, from Latin citō, from Latin -tō, from Latin -tus, from Proto-Italic -tus, from Proto-Indo-European -tus — Derives action nouns from verb roots.

Definitions

Ancestry of “oscitaturus”, step by step

Step	Language	Word	Meaning
1	Latin	ōscitō	to open one's mouth, gape
2	Latin	citō	quickly, fast
3	Latin	-tō	Forms here
4	Latin	-tus	Forms the past participle of verbs; Forms...
5	Proto-Italic	-tus	—
6	Proto-Indo-European	-tus	Derives action nouns from verb roots

Every word from Proto-Indo-European -tus →Every word from Latin -tus →Every word from Latin -tō →