First discovery of theropod teeth from the Nenjiang Formation (early Campanian) in the Songliao Basin, northeast China.

Recently, a new fossil site containing microvertebrate remains has been discovered in the upper part of the Nenjiang Formation (early Campanian) in the Songliao Basin, northeast China. Five isolated theropod teeth were discovered. The teeth were analysed based on morphological traits and the results showed that they correspond to the clades of Troodontidae, Dromaeosauridae and ?Tyrannosauridae. One dromaeosaurid tooth can be furtherly assigned to Dromaeosaurinae. It is the first discovery of theropod teeth from the Nenjiang Formation, also the first record of the Dromaeosaurinae from China. This study extends the known geographic range of these clades of theropods. The new materials also expand knowledge of the terrestrial ecosystem during the Late Cretaceous of the Songliao Basin. [ABSTRACT FROM AUTHOR]