As long as we're on languages, such things as "cases" and "declensions" are a lot of the reason Latin eased off into the "romance" languages (French, Italian, Spanish , Portuguese, and a smattering of Romanian).
The reason it's "super hanc petram" is because "super" ("above" or "on") is one of the prepositions that required the accusative case. Other prepositions required the ablative case.
German also has "cases", which are modifications (endings) on nouns or adjectives depending on the use in the sentence. Aus, auser, bei, mit, nach, zeit, von, and zu are known as the "dative" prepositions, meaning that they require the "dative" case (indirect object, usually).
With cases, nominative = subject, genitive = possessive, accusative = direct object, and dative = indirect object. Latin also had "ablative" and "vocative". German settled for just the four.