Shallow oceans cover much of the continents, breaking the land into large islands. Mammals remain small, possibly nocturnal. Most modern groups of organisms appear. During this period, following the extinction of the dinosaurs, mammals evolved from small shrew-like types into all the diverse types around today, as well as many different prehistoric forms. The modern world.
Land masses take their present shape.
The climate, originally tropical, becomes increasingly more seasonal as ice age conditions develop, possibly triggered by the rise of the Himalayan mountain uplift.