A sauropod track assemblage from a surface in the Upper Jurassic fluvial Tianchihe Formation at the Guanxi site, Shanxi Province, China, is re-documented and analysed in detail, together with a recently discovered new locality situated nearby. In contrast to earlier reports, the former includes four trackways plus isolated tracks (41 tracks in total) instead of five trackways (37 tracks in total) identified earlier, with pes prints reaching more than 60 cm in length. The new site has three pes-manus track pairs belonging to smaller individuals, with pes prints being about 20 cm in length. The absence of larger sized tracks at this locality suggests the possible presence of size-differentiated groups representing juveniles or subadults. Track morphology, heteropody and the medium-wide gauge trackway pattern at both sites support an assignment to the ichnogenus Brontopodus. Trackmakers were eusauropods, possibly mamenchisaurids or more advanced forms such as macronarians. Results of re-investigation allow a new interpretation of trackway orientations and trackmaker behaviour, respectively, as well as a calculation of progression speeds that suggest walking movement.
The Middle Triassic (Anisian) Guanling Formation in Yunnan and Guizhou provinces, southwestern China, is well-known for its marine-reptile fauna with numerous well-preserved skeletons. Tetrapod footprints from this unit have been reported of both terrestrial and marine forms documenting a marginal marine environment in the eastern Tethys region. In particular Chirotherium barthii, an ichnospecies that is characteristic of the Middle Triassic (Anisian), was formerly described from the Guanling Formation of Guizhou Province. Recently chirotheriid tracks were also reported from deposits of this unit in Yunnan Province. Here we provide the first detailed documentation of this tracksite. Furthermore, we assign these trackways to the ichnospecies Chirotherium barthii, based on identical features in footprint morphology. Additionally, from the same surface, we describe the first tracks and trackways of the lacertoid ichnogenus Rhynchosauroides from the Asian continent. Trackmakers of C. barthii are non archosaurian archosauriforms or members of the archosaur crown-group, while Rhynchosauroides can be attributed either to lepidosauromorph or archosauromorph diapsids. The environment was a coastal area along the eastern Tethys, with marine, semi-aquatic and terrestrial tetrapods leaving their footprints in the carbonatic sediment of mudflats and lagoons when searching for food, that possibly consisted of small marine invertebrates or the small lacertoid forms being the prey of the larger archosaurs.