Shixue Hu

ABSTRACT The early Middle Triassic (Anisian) Luoping biota serves as a significant example of marine ecosystem recovery following the Permian–Triassic mass extinction. However, the specific burial environment and mechanisms responsible for this exceptional preservation remain to be fully elucidated. The nitrogen isotopic composition of ancient sediments can provide valuable insights into the nitrogen biogeochemical cycle of the ocean and the redox conditions of the water column.

The tracks were first discovered on top of bed 43 (associated with protorosaur skeletal fossils) and beds 32 and 34, in April 2009 during the first fossil excavation in quarry 1 of the Luoping biota, exposing the Shangshikan section13. Much more abundant and varied trace fossils were then found during the second excavation, in quarry 2 (Menqianpo section). These tracks occur on bed 107 (Fig. 1b), higher in the section than the isolated finds from the Shangshikan section.