Reinterpretation of dinosaur footprints from the Lower Cretaceous of Huanglonggou, Zhucheng, Shandong Province, China: Comment on “Tracking the yellow dragons: Implications of China's largest dinosaur tracksite (Cretaceous of the Zhucheng area, Shandong P

Zhucheng, located in eastern Shandong Province, China, is well-known for its abundant Early Cretaceous dinosaur footprints and Late Cretaceous dinosaur bone fossils. Recently, Lockley et al. (2015) presented a sketch study on the Huanglonggou tracksite in the Zhucheng area, and critically commented on our paper (H. Xu et al., 2013), which conducted a detailed and comprehensive study of the tracksite. Here, we demonstrate that some of their assumptions and comments on our work are subjective and incorrect. Tracks at the Huanglonggou tracksite, including a dominant theropod (large theropod, Grallator yangi/Paragrallator, Corpulentapus lilasia), and subordinate sauropod, suspected ornithopod, and turtle tracks were preserved in the Yangjiazhuang Formation with estimated ages of 129 to 122 Ma, rather than in the Longwangzhuang Formation as proposed by Lockley and his associates. Contrary to Lockley et al. (2015), our mapping of the Huanglonggou tracksite exhibits the previous work by Li et al. (2011) and focuses on the 50 well-preserved trackways and their orientations. Based on the stride length to footprint size index diagram and the Grallator-Anchisauripus-Eubrontes (GAE) plexus, our statistical constraints on the three species of theropods are better than those of Lockley et al. (2015). Lockley argued that tracks at the site were preserved on at least five levels, of which the majority on level 4 were of excellent preservation. In fact, the tracks identified throughout the site have been from only one level. The false appearance of multiple levels is interpreted as the result of sedimentation at the shoreline and differential excavation of the tracksite.