Cenozoic

Fossil of plants, invertebrates, vertebrates, and trace fossils have been identified in Yellowstone National Park from more than 40 stratigraphic units spanning more than 540 million years from the Cambrian to the Cenozoic eras.

The whole history of the earth is divided into five eras, with corresponding rock-systems. These are: 1. Archæan or Eozoic¹ era, embodied in the Laurentian system; 2. Palæozoic² era, embodied in the Palæozoic or Primary system; 3. Mesozoic³ era, recorded in the Secondary system; 4. Cenozoic,⁴ recorded in the Tertiary and Quaternary systems; and, 5. The Psychozoic era, or era of Mind, recorded in the recent system.

The researchers found that the first day of the Cenozoic was peppered with cataclysms. When the asteroid struck, it temporarily carved a hole 60 miles across and 20 miles deep.