Early Triassic chondrichthyans from the Zuodeng Section, Guangxi Province, South China: Palaeobiological and palaeobiogeographical implications

Abstract

The Early Triassic chondrichthyans from China have been insufficiently studied. We herein present a taxonomic study of a diverse chondrichthyan fauna from the Luolou Formation at the Zuodeng section in Guangxi Province, South China. Nine elasmobranch taxa are recognized, including two hybodonts (Omanoselache halli and Hybodontiformes indet.), three neoselachians (Safrodus tozeri, Polyfaciodus pandus and Synechodus aff. triangulus) and four euselachians of uncertain affinities (Favusodus orientalis, Euselachii gen. et sp. indet., ‘Hybodus’ zuodengensis and ‘Hybodus’ yohi). A statistical analysis shows that the shark palaeocommunity had a high diversity and evenness, and a low dominance, indicating that the archipelagic Nanpanjiang Basin probably allowed euselachian sharks to thrive. Their diverse morphologies indicate that the fauna demonstrated adaptation for a wide diversity of feeding strategies, including grasping-crushing, grasping-swallowing and sharp-grasping. Palaeobiogeographically, trans-Tethyan taxa reveal a shark dispersion path between the western Neo-Tethys (Oman) and eastern Palaeo-Tethys (Zuodeng) in the Early Triassic.