Early Jurassic palaeoclimate in Southwest China and its implications for dinosaur fossil distribution

Abstract

Lufeng County in Southwest China is one of the most famous lagerstätten in which Early Jurassic dinosaurs can be found. The reason for the burial of large body size dinosaur fossils at this site is still an enigma, although it could be attributed to either suitable habitats or good preservation conditions. Both of these factors are indirectly regulated by climatic conditions. Therefore, a quantitative reconstruction of the terrestrial palaeoclimate of the Lufeng area during the Early Jurassic could help shed new light on this issue. In this study, we analysed the stable isotope compositions of oxygen and carbon (δ13C and δ18O) in apatite phosphate and carbonate from the tooth enamel and compact bones of basal sauropodiform andSinosaurusfossils. The oxygen isotopes provided a mean annual temperature (MAT) of ≥21 ± 3°C, and the carbon isotopes allowed us to estimate a mean annual precipitation (MAP) of 965 ± 460 mm/yr during the Early Jurassic in Lufeng County. These conditions correspond to a relatively arid tropical savanna climate hospitable to vertebrate life. We also compared the spatial relationship between the global distribution of dinosaur fossils and climatically sensitive deposits during the Jurassic. The dinosaur fossil distribution reveals a strong preference for arid regions. We therefore suggest that ‘savanna‐like’ tropical conditions helped accommodate a large number of dinosaurs and preserve their carcasses in the Lufeng area during the Early Jurassic.