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Triassic

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. The Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events.

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

 Rhaetian (Upper Triassic)
 Noranian/Alaunian (Upper Triassic)
 Carnian/Tuvalian/Julian (Upper Triassic)
 Ladinian (Middle Triassic)
 Anisian/Illyrian/Pelsonian/Aegean (Middle Triassic)
 Spathian/Olenekian (Scythian=Early Triassic)
 Nammalian/Induan/Olekian/Smithian/Dienerian (Scythian=Early Triassic)
 Gresbachian/Induan/Ellesmerian/Gangetian (Scythian=Early Triassic)

The Triassic is the first Era of the Mesozoic Era -- the Age of Dinosaurs.

During the Triassic, almost all the Earth's land mass remained concentrated into one Supercontinent -- Pangea. Climates were warm with no evidence of glaciation. As far as can be determined, there was no land 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.

During the Triassic marine life reached a more or less stable state with the "highest" life forms being fish and marine reptiles. Among invertebrates brachiopods and mollusks remained common. Shelled cephalopods in particular were common and diverse. On land, large sophisticated reptiles became dominant. 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.

See also; Geologic timescale



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