oligocene epoch Definition

oligocene, permian period, miocene epoch, triassic period, cretaceous period, jurassic period, cambrian period, devonian period, eocene epoch, cenozoic era, faunas, pleistocene epoch, cenozoic, neogene, upper paleolithic, holocene epoch, interglacial, pliocene epoch, phanerozoic, genus australopithecus, paleozoic era, mesozoic era, carboniferous period, tertiary period, middle paleolithic, mya, homo heidelbergensis, angiosperm, deglaciation, paleolithic age, ostracods, placental mammal, brachiopods, archaean, neolithic age, glaciation, noachian, biogeographical, eukaryote, plesiosaurs, comb jelly, paleocene, carboniferous, quaternary period, trilobites, paleogene, conodonts, laurasia, supercontinent, stegodon, theropod dinosaur, paranthropus, eocene, iguanodon, habilis, gondwanaland, australopithecines, toothed whale, molluscan, ordovician, staghorn coral, placentals, floras, lower paleolithic, isopods, fossil, pleistocene, minoan civilization, microfossils, hadean, mesozoic, sauropod dinosaur, fossilisation, paleoecology, semidesert, flatfishes, stromatolite, mycenaean, hominoid, pliocene, mammuthus, amphipods, prehistory, mesolithic, lower palaeolithic, homo erectus, coevolution, columbian mammoth, eastern lowland gorilla, stegosaurs, subpolar, megafauna, robustus, ichthyosaur, dinosauria, bryozoans, volcanism, diatom, geochronology, bryophytes,