In the geologic timescale , the Middle Triassic is the second of three epochs of the Triassic period or the middle of three series in which the Triassic system is divided in chronostratigraphy . The Middle Triassic spans the time between 247.2 Ma and 237 Ma (million years ago). It is preceded by the Early Triassic Epoch and followed by the Late Triassic Epoch. The Middle Triassic is divided into the Anisian and Ladinian ages or stages .
4-516: The San Salvatore Dolomite , sometimes known as the Salvatore Dolomite or San Salvatore Formation , is a Middle Triassic (late Anisian ) geological formation in Switzerland and Italy . The primarily lithology is micritic dolomite with a high proportion of algal mounds ( stromatolites ). It corresponds to a thick warm-water carbonate platform on the northern edge of an island in what
8-533: A deeper and more anoxic basin between carbonate platforms. This article about a specific stratigraphic formation in Europe is a stub . You can help Misplaced Pages by expanding it . Middle Triassic Formerly the middle series in the Triassic was also known as Muschelkalk . This name is now only used for a specific unit of rock strata with approximately Middle Triassic age, found in western Europe. Following
12-656: Is now the Po Plain . This formation and its local equivalents are common in the hills around Lake Maggiore , Varese , and Lugano , preserving fossils of marine invertebrates such as ammonoids , gastropods , and bivalves . At its southernmost extent on Monte San Giorgio , only the lower part of the San Salvatore Dolomite is preserved. The middle and upper parts are replaced by the Besano Formation , San Giorgio Dolomite , and Meride Limestone , which were deposited in
16-514: The Permian–;Triassic extinction event , the most devastating of all mass-extinctions, life recovered slowly. In the Middle Triassic, many groups of organisms reached higher diversity again, such as the marine reptiles (e.g. ichthyosaurs , sauropterygians , thallatosaurs ), ray-finned fish and many invertebrate groups like molluscs ( ammonoids , bivalves , gastropods ). During
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