At the outset of the Cainozoic period the climate of the world was austere.
The differences between the life of the Cainozoic and Mesozoic periods are far profounder than the resemblances.
And the terms Palæozoic, Mesozoic, and Cainozoic, are used to indicate these three successive systems of life.
The mesozoic and cainozoic systems occupy the surface area to the westward.
The differentiation of the climate during one stage of the Cainozoic era is well illustrated by the Miocene flora.
