Discovery of early proasaphiscid trilobites in Tangshan area, North China, and revision of some genera and species
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Abstract:
This study of proasaphiscid trilobites is based on some type specimens and new materials (topotypes) collected from the type sections at Longwangmiao, Qujing in eastern Yunnan as well as at Sanwan, Nangao, Danzhai, Kaili and Meitan in Guizhou. The diagnoses and occurrences of Kuetsingocephalus and Danzhaiaspis have been revised, and the ratio of preglabellar field to glabellar length is here considered as the main crucial distinction between the two genera. In Kuetsingocephalus the ratio of preglabellar field to glabellar length is less than 24%, but in Dan-zhaiaspis it is more than 30%. In Danzhaiaspis all pleural ribs are visible, while in Kuetsingocephalus only the first pair of pleural ribs is visible. One new genus and three new species have been established herein: Qizuoshania tang-shanensis gen. et sp. nov., Danzhaiaspis intermedius sp. nov., and Kuetsingocephalus fengrunensis sp. nov. With exception of oryctocephalids, the proasaphiscid trilobites are of very important significance for defining the boundary of Cambrian Series 2 and Miaolingian Series in North China Platform and the Yangtze Platform owing to its wide distribution and rapid evolution in China.