In Latin we have the ablative case case. We often use itIts common uses can be described as instrumental and locative (ablativus loci). But in Slavonic languages we have a separate case: thedistinct locative case.
What was first: didDid the instrumental and locative merge into one case in Latin, or did the Slavonic language invent the separate cases? When did this happen? Why don't we have a distinct locative case in Latin?