Earliest epoch of Tertiary period. First epoch of the Tertiary period of geological time, 65–55 million years ago. Many types of mammals spread rapidly after the disappearance of the great reptiles of the Mesozoic.From 58 million to 63 million years ago; appearance of birds and earliest mammals; Also called: Paleocene epoch.
From 40 million to 58 million years ago; presence of modern mammals; Also called: Eocene epoch.
Second epoch of the Tertiary period of geological time, 56.5–35.5 million years ago. Originally considered the earliest division of the Tertiary, the name means “early recent”, referring to the early forms of mammals evolving at the time, following the extinction of the dinosaurs.
From 25 million to 40 million years ago; appearance of sabertoothed cats; Also called: Oligocene epoch.
Third epoch of Tertiary period.
Third epoch of the Tertiary period of geological time, 35.5–3.25 million years ago. The name, from Greek, means “a little recent”, referring to the presence of the remains of some modern types of animals existing at that time.
From 13 million to 25 million years ago; appearance of grazing mammals; Also called: Miocene epoch.
Fourth epoch of the Tertiary period of geological time, 23.5–5.2 million years ago. At this time grasslands spread over the interior of continents, and hoofed mammals rapidly evolved.
From 2 million to 13 million years ago; growth of mountains; cooling of climate; more and larger mammals; Also called: Pliocene epoch.
Fifth and last epoch of the Tertiary period of geological time, 5.2–1.64 million years ago. The earliest hominid, the humanlike ape Australopithecines, evolved in Africa.
See also human species.
In the Roman Catholic Church, a member of a “third order” (see under holy orders); a lay person who, while marrying and following a normal employment, attempts to live in accordance with a modified version of the rule of one of the religious orders. The first such order was founded by St Francis 1221.
Period of geological time 65–1.64 million years ago, divided into five epochs: Paleocene, Eocene, Oligocene, Miocene, and Pliocene. During the Tertiary, mammals took over all the ecological niches left vacant by the extinction of the dinosaurs, and became the prevalent land animals. The continents took on their present positions, and climatic and vegetation zones as we know them became established. Within the geological time column the Tertiary follows the Cretaceous period and is succeeded by the Quaternary period.