New ichthyofaunal microfossils from the Late Permian at Chaotian, Sichuan, Southwest China

Abstract Chondrichthyan remains are reported for the first time from the Late Permian of the Sichuan Province, Southwest China. They include four tooth genera, comprising Eugeneodontiformes (aff. Agassizodus sp. and Eugeneodontiformes indet.) and Euselachii ( Favusodus cf. orientalis and Neoselachii gen. et sp. indet.), as well as two morphotypes of dermal denticles. Eugeneodontiforms and euselachians are represented by durophagous sharks, which are the most common component of the described assemblage. Aff. Agassizodus sp. probably represents a new helicoprionid shark that features a trilobate tooth root with two distinct lingual foramina. The Neoselachii gen. et sp. indet. probably also represents a new taxon and could be the first Palaeozoic neoselachian shark with a holaulacorhize root vascularization. Moreover, high-resolution micro-computed tomography (micro-CT) images were used to investigate the 3D structural characteristics of their dental histology. The aff. Agassizodus sp. displays isolated branching pulp canals connecting with pulp cavities, whereas the Neoselachii gen. et sp. indet. shows networked pulp canals without a pulp cavity.