Editing Maotianshan Shales (section)

== History and scientific significance ==
Although fossils from the region have been known from the early part of the 10th century, Chengjiang was first recognized for its exquisite states of preservation with the 1984 discovery of the [[naraoiidae|naraoiid]] ''[[Misszhouia]]'', a soft-bodied relative of [[trilobite]]s. Since then, the locality has been intensively studied by scientists throughout the world, yielding a constant flow of new discoveries and triggering an extensive scientific debate surrounding the interpretation of discoveries. Over this time, taxa have been revised or reassigned to different groups. Interpretations have led to many refinements of the [[phylogeny]] of groups<ref>{{Cite journal |last1=Saleh |first1=Farid |last2=Ma |first2=Xiaoya |last3=Guenser |first3=Pauline |last4=Mángano |first4=M. Gabriela |last5=Buatois |first5=Luis A. |last6=Antcliffe |first6=Jonathan B. |date=2022-08-23 |title=Probability-based preservational variations within the early Cambrian Chengjiang biota (China) |journal=PeerJ |language=en |volume=10 |pages=e13869 |doi=10.7717/peerj.13869 |doi-access=free |pmid=36032952 |pmc=9415357 |issn=2167-8359}}</ref><ref>{{Cite journal |last1=Xianguang |first1=Hou |last2=Ramsköld |first2=Lars |last3=Bergström |first3=Jan |date=1991 |title=Composition and preservation of the Chengjiang fauna –a Lower Cambrian soft-bodied biota |url=https://onlinelibrary.wiley.com/doi/10.1111/j.1463-6409.1991.tb00303.x |journal=Zoologica Scripta |language=en |volume=20 |issue=4 |pages=395–411 |doi=10.1111/j.1463-6409.1991.tb00303.x |issn=0300-3256}}</ref> and even the erection of the new phylum [[Vetulicolia]] of primitive [[deuterostomes]].<ref name=":2">{{Cite journal |last=Shu |first=Degan |date=2005 |title=On the Phylum Vetulicolia |url=http://link.springer.com/10.1007/BF03183746 |journal=Chinese Science Bulletin |language=en |volume=50 |issue=20 |pages=2342–2354 |bibcode=2005ChSBu..50.2342S |doi=10.1007/BF03183746 |issn=1001-6538 |s2cid=86827605}}</ref><ref name=":3">{{Cite journal |last1=Briggs |first1=Derek E. G. |last2=Fortey |first2=Richard A. |date=2005 |title=Wonderful strife: systematics, stem groups, and the phylogenetic signal of the Cambrian radiation |url=https://www.cambridge.org/core/product/identifier/S0094837300025331/type/journal_article |journal=Paleobiology |language=en |volume=31 |issue=2_Suppl |pages=94–112 |doi=10.1666/0094-8373(2005)031[0094:WSSSGA]2.0.CO;2 |issn=0094-8373 |s2cid=44066226}}</ref>

The Chengjiang biota has all the animal groups found in the Burgess Shale; however, since it is ten million years older, it more strongly supports the deduction that metazoans diversified earlier or faster in the early Cambrian than does the Burgess Shale fauna alone. The preservation of an extremely diverse faunal assemblage renders the Maotianshan shale the world's most important for understanding the evolution of early multi-cellular life, particularly the members of phylum [[Chordata]], which includes all [[vertebrates]]. The Chengjiang fossils comprise the oldest diverse [[metazoan]] assemblage above the [[Proterozoic]]-[[Phanerozoic]] transition and, thus, the [[fossil record]]'s best data source for understanding the apparently rapid diversification of life known as the [[Cambrian Explosion]].

One of the most intriguing locations of the Chengjiang biota is the Haiyan Lagerstätte where hundreds of juvenile specimens have been found. This unique location offers insights into the development of most animal groups and as such is a unique deposit in the Cambrian.<ref name=YangEtAl2021>{{cite journal
|journal=Nature Ecology & Evolution
|volume=5
|issue=8
|doi=10.1038/s41559-021-01490-4
|pages=1082–1090
|year=2021|title=A juvenile-rich palaeocommunity of the lower Cambrian Chengjiang biota sheds light on palaeo-boom or palaeo-bust environments
|last1=Yang
|first1=X.
|last2=Kimmig
|first2=J.
|last3=Zhai
|first3=D.
|last4=Liu
|first4=Y.
|last5=Kimmig
|first5=S. R.
|last6=Peng
|first6=S.
|pmid=34183806
|bibcode=2021NatEE...5.1082Y
|s2cid=235674619
}}</ref>

===IUGS geological heritage site===
In respect of 'the Chengjiang fossils represent[ing] an uparalleled record of the fundamentally important rapid diversification of metazoan life in the early Cambrian', the [[International Union of Geological Sciences]] (IUGS) included the 'Cambrian Chengjiang fossil site and lagerstätte' in its assemblage of 100 'geological heritage sites' around the world in a listing published in October 2022. The organisation defines an 'IUGS Geological Heritage Site' as 'a key place with geological elements and/or processes of international scientific relevance, used as a reference, and/or with a substantial contribution to the development of geological sciences through history.'<ref>{{cite web |title=The First 100 IUGS Geological Heritage Sites |url=https://iugs-geoheritage.org/videos-pdfs/iugs_first_100_book_v2.pdf |archive-url=https://web.archive.org/web/20221027114156/https://iugs-geoheritage.org/videos-pdfs/iugs_first_100_book_v2.pdf |archive-date=2022-10-27 |url-status=live |website=IUGS International Commission on Geoheritage |publisher=IUGS |access-date=13 November 2022}}</ref>