Early Middle Jurassic vertebrate microremains from the Three Gorges area, southern China

Abstract

Vertebrate microremains were collected from the Middle Jurassic freshwater deposits of the Lower Member of the Xietan Formation in the Three Gorges area, Hubei Province, People's Republic of China. They include remains of hybodont sharks (Hybodus aff. “H.” parvidens, Hybodus sp., cf. Parvodus sp., Polyacrodus sp. and Hubeiodus ziguiensis gen. et sp. nov.), an actinopterygian fish, and a crocodyliform. The diversity of hybodont sharks in the Xietan Formation and the appearance of a peculiar pattern of tooth morphology in Hubeiodus ziguiensis suggest the adaptive radiation of these sharks in freshwater systems in China during the Middle Jurassic. This diversification led to the rich endemic hybodont faunas of the Lower Cretaceous in Asia.

Keywords:

• Actinopterygii
• China
• Crocodylomorpha
• Elasmobranchii
• Middle Jurassic
• Three Gorges

Acknowledgements

This study was financially supported by State Key Laboratory of Palaeobiology and Stratigraphy (Nanjing Institute of Geology and Palaeontology, CAS) (No. 063105) and by the Major Basic Research Projects (2006CB806400) of MOST (The Ministry of Science and Technology) of China. GC's work in China was made possible by a research grant from the Carlsberg Foundation. We also thank Jan Rees (University of Karlstad) for helpful discussions on some of the specimens described in this article. We are sincere thank to K. Shimada (DePaul University) for reviewing this manuscript, making helpful suggestions and clear-cut modifications.