Discovery of the diminutive theropod track Minisauripus from the Junan Geopark, Shandong Province, China

Six diminutive dinosaur tracks, ascribed to the ichnogenus Minisauripus, were discovered in the Lower Cretaceous (Baremmian-Alpin) Tianjialou Formation of the Dasheng Group in the Junan Geopark, Shandong Province, China. Of these, five are larger (~6 cm long, including claw traces) and one is smaller (~3 cm long). The five “large” tracks, four of which form two trackway segments, occur on the lower two surfaces with Minisauripus, which we call the ‘main’ Minisauripus level; and the “small” track occurs at a different stratigraphic level ~30 cm above the lower surfaces. One of the segment consists of a right (A) and a left footprint (B), while the other segment a left (C) and a right footprint (D), with a pace length of ~60 cm. The Shandong specimens show the following features: small, elongate and slightly asymmetrical tridactyl tracks; individual digit impressions parallel sided, and well padded with blunt distal terminations; traces of narrow claws sometimes preserved; digit III slightly longer than digit IV, which is slightly longer and narrower than digit II. Track length to pace length ratio is about 1∶10 for the larger tracks. The Shandong specimen is anomalous in that its five larger tracks are about twice the size of the Sichuan or Korean tracks. The discovery of Shandong Minisauripus marks the third locality for Shandong following Sichuan and Korea worldwide.