[Edit]

Shorter times

34.7 million years -- half-life of niobium-92

36 million years -- time since end of Eocene Epoch and beginning of Oligocene Epoch, age of the Cercopithecidae (Old World primates) superfamily.

40 million years -- Estimated period of time until Australia will collide with Asia, time since the age of the Catarrhini parvorder.

65 million years -- time since Cretaceous-Tertiary extinction event at end of Cretaceous Period (end of Mesozoic Era) and beginning of Tertiary Period (beginning of Cenozoic Era), age of the Haplorrhini suborder.

135 million years -- time since end of Jurassic and beginning of Cretaceous Period.

195 million years -- time since end of Triassic and beginning of Jurassic Period, age of the earliest mammals.

225 million years -- time since end of Permian Period (end of Palaeozoic Era) and beginning of Triassic Period (beginning of Mesozoic Era).

250 million years -- Galactic year - A revolution around the center of Milky way of Sun and the Solar system.

280 million years -- time since end of Carboniferous and beginning of Permian Period.

Longer times