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 .
4-522: The Yangliujing Formation is a Middle Triassic geologic unit found in the Guizhou and Yunnan Provinces of southern China . Most of the formation is represented by massive dolomites , indicative of a shallow-water depositional environment. Fossils are generally rare, but conodonts from the Anisian - Ladinian boundary (namely several species of Neogondolella ) are known from the lower part of
8-522: The formation. Some marine reptiles have been found in dolomitic limestone near Dingxiao, an area of Guizhou sometimes considered to preserve the upper part of the Yangliujing Formation. However, under a more restrictive definition of the Yangliujing Formation, the fossils of Dingxiao would instead belong to the overlying Zhuganpo Formation . The following fossils have been reported from the formation: Middle Triassic Formerly
12-487: The marine reptiles (e.g. ichthyosaurs , sauropterygians , thallatosaurs ), ray-finned fish and many invertebrate groups like molluscs ( ammonoids , bivalves , gastropods ). During the Middle Triassic, there were no flowering plants, but instead there were ferns and mosses. Small dinosauriforms began to appear, like Nyasasaurus and the ichnogenus Iranosauripus . This article related to
16-531: 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 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
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