Deinonychosaurian theropods, the dinosaurian sister group of birds, are characterized by a large raptorial claw borne on a highly modified second digit that was thought to be held in a retracted position during locomotion. In this study, we present new trackway evidence for two coeval deinonychosaurian taxa from the Early Cretaceous of Shandong, China that indicate a hitherto unrecognized body size diversity for this period and continent. These fossil tracks confirm diversity and locomotory patterns implied by phylogeny and biogeography, but not yet manifested in the body fossil record. Multiple parallel and closely spaced trackways generated by the larger track maker provide the best evidence yet discovered for gregarious behavior in deinonychosaurian theropods.
Bibliographical noteFunding Information:
Acknowledgments This study was supported financially in part by National Natural Science Foundation of China grant 40572011 to RH. L. Additional support was provided by the University and Society Collaboration of the Japanese Ministry of Education, grant-in-aid 1183303, 1999-2000 to M. M., and by the University of Colorado at Denver Dinosaur Tracks Museum to M. G. L. M.A.N. and P.J.M. were both supported by US National Science Foundation AToL EAR 0228607 and by the AMNH and FMNH, respectively. S. Harris produced the movie and M. Ellison photographed the seriema foot for Fig. 4.