Maotianshan Shales

The Maotianshan shale is a late pre-Cambrian (Atdabanian) rock formation, of ca 522 Mya, now lying exposed in the Yunnan Province of China in the villages of Ercaicun and Chengjiang near the city of Kunming. Nearly 50 meters of mudstone sedimentary strata are exposed, revealing many excellently-preserved soft-bodied fossilized organisms, which form a major Lagerstätte, "probably the most significant exceptional preservation above the Precambrian-Cambrian boundary (c. 543 Ma)" [1]. At the time these sediments were laid down, this section of the Yangtze plateau lay in an equatorial zone. Some brachiopods that are found in situ and the gut contents of some mud-ingesting animals both indicate a warm, shallow sea with a muddy bottom.

These shales were discovered around 1984 by Xianguang Hou, 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, as well as the somewhat younger Emu Bay shale of South Australia. 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.

Fossil Species

Arthropods

Acanthomeridion
Anomalocaris
Canadaspis
Chengjiangocaris
Chuandianella
Fortiforceps
Fuxianhuia
Kuamaia
Kuanyangia, a trilobite
Leanchoilia
Naraoia
Retifacies
Saperion
Sinoburius
Squamacula
Xandarella
Yunnanocephalus, a trilobite

Worms and relatives

Hallucigenia
Microdictyon
Palaeoscolex

Chordates

Others

Dinomischus
Eldonia
Maotianshania
Opabinia
Xidazoon

References

"Fossil Lagerstätten" (Web page). Department of Earth Sciences, University of Bristol. 2003. Retrieved November 21. {{cite web}}: Check date values in: |accessdate= (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help) - A catalogue of sites of exceptional fossil preservation produced by MSc palaeobiology students at University of Bristol's Department of Earth Sciences.
"Chengjiang" (Web page). Retrieved November 22. {{cite web}}: Check date values in: |accessdate= (help); Unknown parameter |accessyear= ignored (|access-date= suggested) (help)
Hou, Xian-Guang (2004). The Cambrian Fossils of Chengjiang, China: The Flowering of Early Animal Life. Blackwell Publishers. ISBN 1405106735. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
Chen, J. Y. (1997). The Chengjiang Biota - A Unique Window of the Cambrian Explosion. ISBN 9578503474. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)