Olivier Rieppel, Department of Geology, The Field Museum, Chicago, IL 60605--2496
Excavation and research over the last 15 years have generated insights into an impressive variety of Triassic marine reptiles from southern China. The first discoveries were made in the Guanling area, Guizhou Province, revealing an early Late Triassic fossil Lagerstätte yielding predominantly reptiles and crinoids. Today, fossiliferous localities are known from Anhui, Guizhou, Yunnan, and Hubei Provinces, collectively extending from the late Lower Triassic (Olenekian) to the early Upper Triassic (Carnian). The Triassic biota of southern China are remarkably rich and diverse in ichthyosaurs, sauroperygians (placodonts, pachypleursaurs, nothosaurs, and cymatosaurs), and – uniquely on a global scale – thalattosaurs, but protorosaurs, the enigmatic saurosphargids, and even archosaurs as well as turtles are also represented. Not surprisingly, the closest paleogeographical affinities of these eastern Tethyan biota (originally deposited on the South China Block) are with the western Tethys, such as the Middle Triassic marine fauna known from Monte San Giorgio and Besano, located in southern Switzerland and Lombardy (Italy) respectively. The two faunal provinces were at the time conveniently connected by a string of exotic terranes drifting northwards from Gondwanaland and straddling the equator during the Triassic. There are, however, possible faunal affinities of Tethyan Triassic faunas with contemporary biota of the eastern Pacific faunal province (western North America), which in the case of marine reptiles predominantly populating coastal waters are hard to explain on the current reconstruction of Pangaea.