Grallatorid–eubrontid tridactyl track assemblages from Lower Jurassic, Sichuan Province, China: Insights into theropod diversity, locomotion and behavior

The Sichuan Basin in southwestern China is home to the most extensive theropod track record in the Lower Jurassic of China, comprising a range of minute- to medium-sized tracks that form the grallatorid–eubrontid (GE) plexus. The majority of these had previously been discovered in the Ma'anshan Member of the Ziliujing Formation. New material described herein is from the Wuli tracksite that suggests a flourishing paleoecological scene in a temporary waterfront habitat. Upon reviewing the GE plexus at different scales, we consider the locomotion style of these early theropod trackmakers, which likely included the 'grounded-running' gait of extant birds, as well as the possibility of a tail trace that may be related to intra- or interspecific interactions.