Some nouns derived from verbs look like future participles: cultura from colere, sepultura from sepelire, scriptura from scribere… These do not have a future meaning, but are merely names for the activity associated with the verb. Are they actually related to the future participle in one way or another? Or do they just happen to have an unrelated suffix that looks the same?
Gary Miller, in Latin Suffixal Derivatives in English and Their Indo-European Ancestry says that there is no direct relation between nouns formed from verbs with -ura and the similar future active participles.
Formally, this suffix seems to be an adjectival *-ro- (fem. *-reh2) extension of nominal *-t(e/o)u-.... While -tura bears a close resemblance to the future active participle -turus, -a, -um, there is no simple way the two can be related. (p. 118)
He gives three reasons for this lack of resemblance:
- Temporal difference
Since the future active participle futurus, -a, -um is older than the substantivized neuter futurum, pl. futura, the nominal suffix could not have spawned the future participle. (ibid)
Differences in stem formation: Two examples:
- FAP pariturus vs. noun partura
- FAP stātūrus vs. noun statūra (short a)
Similarity with other nominal suffixes
The nominal suffix patterns with -or/-tor (etc.) in having an older form -ura beside -tura (build on stem II). (ibid)
An example of this would be figura and fictura.