The earliest geological epoch of the Palaeogene period. It began about 66 million years ago, following the Cretaceous period, and extended for about 10 million years to the beginning of the Eocene (the Palaeocene is sometimes included in the Eocene). It was named by the palaeobotanist W. P. Schimper in 1874. A major floral and faunal discontinuity occurred between the end of the Cretaceous and the beginning of the Palaeocene (see alvarez event): following the extinction of many reptiles the mammals became abundant on land. By the end of the epoch primates and rodents had evolved.