61:2.8

30,000,000 years ago the modern types of mammals began to make their appearance. Formerly the mammals had lived for the greater part in the hills, being of the mountainous types; suddenly there began the evolution of the plains or hoofed type, the grazing species, as differentiated from the clawed flesh eaters. These grazers sprang from an undifferentiated ancestor having five toes and forty-four teeth, which perished before the end of the age. Toe evolution did not progress beyond the three-toed stage throughout this period.