First discovery of a deinonychosaur trackway from the lower Upper Cretaceous of southeastern China

Abstract

The new deinonychosaur trackway was recovered from the lower Upper Cretaceous Jinhua Formation of Zhejiang Province, southeastern China. This trackway includes nine well-preserved tracks characterized by elongate and didactyl morphology, and thus is assigned to the ichnospecies Velociraptorichnus sichuanensis. This trackway enables more accurate estimations of the speed and gait of the trackmaker for the ichnogenus Velociraptorichnus than the previous studies because the latter is based only on two consecutive tracks. Due to substantial differences in hindlimb proportions between the two clades assignable to the trackmaker of Velociraptorichnus, namely Dromaeosauridae and Troodontidae, we calculated the speed of trackmaker for each pattern. The estimated speeds resulted in 6.1 km/h for dromaeosaurids and 4.6 km/h for troodontids, both of which indicate that this trackway was made by a walking gait. This is the first record of a deinonychosaur trackway from the Cretaceous of southeastern China and extends the known distribution of didactyl theropod ichnotaxa. In combination with previous studies, it also suggests that a diverse ichnoassemblage of non-avian theropods was widely distributed in East Asia during that time.