New materials of the Early Cretaceous spinosaurid (Theropoda) teeth of Napai Basin, Fusui County, Guangxi

The late Early Cretaceous vertebrate fauna from the Napai Basin in Fusui County (southwestern Guangxi)is featured mainly by sauropod, theropod, iguanodontian dinosaurs, with other clades such as hybodont sharks, actinopterygians, turtles and crocodiles.This vertebrate fauna shows the close relationships to that of the Khok Kruat Formation in northeastern Thailand, both to be considered as Aptian in age. The newly discovered spinosaurid teeth from the Napai Basin possess such characters: tooth crown sub-circular in cross-section, denticles on carinae absent, longitudinal ridges and flutes distinct with the ridge numbers on each side about 12 to 15. These teeth can be further included within the subfamily Spinosaurinae.Only one morphotype of the spinosaurid teeth is identified from the Napai Basin, which falls within the range of Morphotype Ⅱ (Siamosaurus morphotype) of spinosaurid teeth from the Khok Kruat Formation in northeastern Thailand. The similar spinosaurid teeth most probably suggest their closer affinity of spinosaurids between the Napai Basin in Guangxi and the northeastern Thailand during the late Early Cretaceous.