A diverse ichnofauna from the Cambrian stage 4 Wulongqing formation near Kunming (Yunnan province, South China)

Abstract

A diverse and well-preserved ichnofauna from the Cambrian (Stage 4: Canglangpuan) Wulongqing Formation (Kunming area, Yunnan Province) is reported here for the first time in detail. Early Cambrian ichnoassemblages are common and have been described from many localities worldwide; however, they are rarely associated with a significant body fossil record that enables both a well-defined biostratigraphic calibration of the related ichnofauna and a direct comparison with the possibly related trace originators, as is the case with the Wulongqing Formation. The ichnofauna consists of various simple bedding-plane-parallel and sub-horizontal traces of Planolites-type as well as of branching, treptichnid-type burrows, Phycodes- and Teichichnus-type "spreiten", star-shaped trace structures associated with short, central and vertical burrow structures, and arthropod traces of the Diplichnites-type. Large, star-shaped trace fossils belonging to a new ichnotaxon (Guanshanichnus glockerichnoides igen. et isp. nov.) are reported from the Yangtze Platform for the first time and represent the hitherto oldest (equivalent to Botoman regional stage of Siberia) known evidence of this trace type and further global-scale evidence of this trace type from a shallow-water environment. Arthropod traces appear in less abundance in the middle part of the formation. Several arthropod traces display a significant, V-shaped, paired arrangement of scratch marks onthe bedding plane; their morphology and size correspond with co-occurring trilobite taxa from the Wulongqing Formation, probably indicating the preservation of trilobite resting traces. The Shitangshan trace fauna as part of the Guanshan Fauna provides new insights into the palaeoecology and taphonomy of Chengjiang-type fossil Lagerstätten.