Examples: cartography card archaeology archetype monarchy legal loyal purse personal cinema kinase car carpenter hippopotamus Mesopotamia dative data date
...
Proto-Slavic *u

→ Bulgarian у (inherited)
→ Old Church Slavonic оу (inherited)
→ Lower Sorbian wu (inherited)
→ Lower Sorbian wu- (inherited)
→ Polish u (inherited)
→ Serbo-Croatian u (inherited)
→ Serbo-Croatian у (inherited(sh/ru))
→ Serbo-Croatian у (inherited)
→ Old Novgorodian оу (inherited)