Maotianshan shales
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The Maotianshan shale is an early Cambrian rock formation exposed in the Yunnan Province of China in the villages of Ercaicun and Chengjiang near the city of Kunming.
These shales appear very early in the Cambrian sequence in China. They were discovered around 1984 and have been extensively studied by both Chinese and Western paleontologists. The shales contain a very broad and well-preserved fauna including many of the taxa found in the better known, and substantially younger, Burgess Shale of British Columbia. The fauna is often referred to as "the Chengjiang biota".
In addition to Anomalocaris, Opabinia, Hallucigenia, and other spectacular forms familiar from the Burgess shales, the Maotianshan shales include at least four possible types of chordates, two of which appear to be true fishes. See Haikouella, Haikouichthys, Yunnanozooan, Myllokunmingia. More mundane forms such as trilobites, brachiopods, and sponges are also present. The Maotianshan shales provide even stronger evidence than does the Burgess shale for a Cambrian Explosion wherein a large number of very different animal body plans seem to have appeared in a disconcertingly short time interval.