considered a distant relative of ctenosauriscids, as that family is also placed within Poposauroidea. Further studies confirmed these results. Paleoecology and taphonomy The Lotosaurus site was once believed to have been as old as the Anisian stage of the early Middle Triassic, about 245-237 million years ago. However, a 2018 analysis suggested a younger date based on Uranium-Lead dating from 189 sampled Zircon grains. The youngest grain sampled gave a date of 225.6 mya, in the early Norian stage of the Late Triassic. However, this grain is a lone outlier in the sample, indicating that it may have leaked lead. Using the next youngest grains, which were clustered in a set and probably more reliable, the weighted mean age of the bonebed was found to be either 238.9 to 229.3 mya (considering the lower intercept of the U-Pb graph), or 244.3 to 228.3 mya (considering the mean age of the youngest cluster of grains). Of these two options, the former has less deviation between ages and may be more accurate. Regardless, the age of the bonebed has only a small chance of belonging to the Anisian stage, and the Lotosaurus specimens which died within the bonebed were more likely to have been alive during the Ladinian or Carnian stages of the Late Middle Triassic or early Late Triassic. A subsequent 2019 study weighted mean age of 238.0 ± 1.4 Ma (Ladinian) as the maximum depositional age for the sandstones preserving fossils of Lotosaurus. The Lotosaurus site was once near the northern shore of the South China Craton, a subcontinent which drifted through Tethys ocean during the Middle Triassic. The South China Craton collided with the North China Craton and the rest of Laurasia at approximately the same time as some of the estimated ages of the site. As a result, it cannot be determined if Lotosaurus was endemic to the SCC while the subcontinent remained an island, or immigrated to the SCC from the NCC after the two merged. Considering that close relatives of Lotosaurus (the shuvosaurids) lived in other regions of Pangaea around that time, the latter hypothesis is currently believed to be more likely. The mineral and microfossil composition of the site suggests that it was a subtropical environment, with pronounced wet and dry seasons. The bonebed in particular would have been part of a floodplain or stream according to ripple marks within the rocks. The large number