Triassic

This period is part of the

Mesozoic era.

Triassic

Jurassic

Cretaceous

The Triassic is a Geologic period that extends from about 195 to 225 million years before the present. As with most older geologic periods, the rock beds that define the start and end are well identified, but the exact dates of the start and end of the period are uncertain by a few million years. The Triassic was named in 1834 by Freidrich Von Alberti for the three distinct layers of redbeds, capped by chalk, followed by black shales that are found throughout Germany and Northwest Europe. As the first Era of the Mesozoic Era (the Age of Dinosaurs), the Triassic follows the Permian and is followed by the Jurassic. Both start and end of the Triassic are marked by major extinction events.

The Triassic is usually separate into Lower, Middle, and Upper subdivisions. The Faunal stages from youngest to oldest are:

Upper Triassic
- Rhaetian (?-203 M.y.)
- Noranian (220-? M.y.)
- Carnian (230-220 M.y.)
Middle Triassic
- Ladinian (233-230 M.y.)
- Anisian (240-233 M.y.)
Lower Triassic (= Scythian)
- Olenkian (?-233 M.y.)
- Indusian (250-? M.y.)

During the Triassic, almost all the Earth's land mass remained concentrated into one Supercontinent -- Pangea. The characteristic sediments of the Triassic (red sandstones and evaporites) suggest a warm dry climate with no evidence of glaciation. As far as can be determined, there was no land or ice caps near either pole. Because of the limited shoreline of one continental mass, Triassic marine deposits are relatively rare despite their prominence in Western Europe. In North America, for example, marine deposits are limited to a few exposures in the West. Due to this, Triassic stratigraphy is mostly based on organisms living in laggons and hypersaline environments, such as Estheria crustaceans.

During the Triassic both marine and continental life show an adaptative radiation, following the permian extinction. New groups appear, such as reptiles (Dinosaurs) in land and shelled cephalopods (Ammonites) in the sea. Corals of the hexacoralia group make their first appearance. The first Angiosperms (flowering plants) may have evolved during the Triassic as did the first flying vertebrates although the latter appear to be flying reptiles, not ancestors of birds.