page_title: Shishugou Formation
section_title: Prehistoric life
hierarchical_section_title: Shishugou Formation / Lithology / Shishugou Formation dinosaur traps / Prehistoric life
caption_attribution_description: Mamenchisaurus sinocanadorum - 03
context_page_description: The Shishugou Formation is a geological formation in Xinjiang, China.
  Its strata date back to the Late Jurassic period. Dinosaur remains are among the fossils that have been recovered from the formation. The Shishugou Formation is considered one of the most phylogenetically and trophically diverse Middle to Late Jurassic theropod fauna.
  The Wucaiwan Member, once considered a separate, underlying formation, is now considered the lowest unit of the Shishugou Formation.
context_section_description: At the time the area was covered by marshland, adjoined a small mountain range peppered with volcanoes, and was inhabited by dinosaurs, small crocodilians and amphibians. Currently it is a sparsely settled region of dry washes, arid badlands and dunes along the Gobi desert’s western edge. The Shishugou Formation consists of mudstone, siltstone, and sandstone, and is named for the silicified wood or petrified logs found here. ('Shishugou' = 'stone tree valley') These badlands were used for some sequences in the film Crouching Tiger, Hidden Dragon, the genus Yinlong ('hidden dragon') being named for the film.
  When the site was first excavated, new species of turtles, crocodilians, pterosaurs, and early mammals were revealed. Many of these species showed the rudiments of characteristics that would later become their hallmarks. One of the first fossil skeletons exposed proved to be that of an unknown theropod, and revealed a stack of four more theropods buried below the first. Yang Zhongjian accompanied the first expedition to the Junggar Basin in 1928, and the fossils found included the medium-size sauropod Tienshanosaurus chitaiensis. Later expeditions stretched from the 1960s to the 1990s and yielded among others the extremely long-necked Mamenchisaurus and the carnivorous Sinraptor. In all, some 600 specimens have been collected.
  On analysis of the rock matrix, large amounts of volcanic ash were found, hinting at eruptions during that period, the ash raining onto the marsh creating viscous mud and becoming subsequent death traps. To date three of these death pits have been located. In one pit a crocodilian was found against a small ceratosaur, in another three decapitated ceratosaurs. The most interesting of the traps gave up the fossil remains of an 80 kg tyrannosauroid named Guanlong, sporting a crest running from its nose to the back of its head. Its discovery was hailed by paleontologists as the earliest known remains of the tyrannosauroid clan that culminated with Tyrannosaurus rex.
caption: Mamenchisaurus sinocanadorum
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