Oligocene rhymes with:
adenosine, biocine, eocene, glycine, internecine, isoprinosine, kerosene, miocene, overseen, paleocene, plasticine, pleistocene, pliocene
Oligocene sounds like:
ohlsen, ohlson, ohlsson, olajuwon, olesen, oleson, olexson, olguin, ollison, olsen, olshan, olson, olsson