age of mammals(n = noun.time) cenozoic, cenozoic era - approximately the last 63 million years; Array
is a kind of era, geological era
is a part of phanerozoic, phanerozoic aeon, phanerozoic eon
has parts: age of man, quaternary, quaternary period, tertiary, tertiary period

age, age bracket, age class, age group, age limit, age norm, age of consent, age of fishes, age of man, age of reason, age of reptiles, age old, bone age, bronze age, chronological age, come of age, developmental age, drinking age, elizabethan age, eolithic age, fertilization age, fetal age, gestational age, golden age, ice age, information age, iron age, legal age, mental age, mesolithic age, middle age, neolithic age, new stone age, of age, old age, paleolithic age, silver age, space age, stone age, stone age man, tender age, victorian age, voting age