Early Devonian chitinozoans from the Nahkaoling Formation in Lingli, Guangxi, South China

The Lower Devonian (Lochkovian and Pragian) in the South China Block is mainly represented by siliciclastic rocks due to the Kwangsian Orogeny. Conodont, which significantly relies on carbonate facies, has limitations in biostratigraphy during this period. To improve the biostratigraphic framework, we systematically studied the lower Pragian chitinozoans from the Gaoling Member of the Nahkaoling Formation at the Lingli section in Nanning, Guangxi. One genus and seven species are identified, including a newly established taxon Angochitina lingliensis sp. nov., the index species of the Angochitina comosa Biozone, associated with A. mourai and A. dimorpha. According to the chitinozoan assemblage and their biostratigraphic ranges at the Lingli section, the A. comosa interval biozone is adopted for this interval. Comparson of the chitinozoan biostratigraphy with conodont biostratigraphy suggests that the A. comosa Biozone in the South China Plate can be correlated with the lowest Pragian Eognathodus irregularis conodont biozone. In addition, the global conodont and chitinozoan biostratigraphic correlations indicate that the A. comosa Biozone recognized at the Lingli section is of the same age as the globally recognized lower Pragian A. comosa Biozone. This study presents a relatively rich collection of chitinozoans from the Gaoling Member of the Nahkaoling Formation, which is the first record for the lowermost Pragian in South China and provides a new data for the high-resolution biostratigraphical subdivisions and correlations for this interval.