Lophialetidae are an extinct group of endemic Asiatic tapiroids that are widely distributed in the Eocene sediments of Asia. Schlosseria magister and Lophialetes expeditus are the most abundant species in this family. However, their dietary and ecological characteristics are largely unknown to date. For the first time, we reconstruct the paleodiet and habitat of these two lophialetids using a combination of mesowear and stable carbon isotope analyses of fossil teeth excavated from the Erlian Basin, China. The mesowear analyses (n=141) suggest that the dietary structure of S. magister and L. expeditus shifted from less abrasive to more abrasive diets from ~52 to ~42 Ma. The stable carbon isotope analyses (n=137) suggest that the habitats of S. magister and L. expeditus became drier and/or more open through time. The dietary shifts of the two lophialetids are consistent with the evident changes in habitat. The changes in the diets and habitat likely were related to global climate change during that time period. The gradual drop in global temperatures during Early-Middle Eocene led to a drier and more open terrestrial ecosystem in the Erlian Basin, probably resulting in changes in floral composition of the environment inhabited by S. magister and L. expeditus. Hence, herbivores highly susceptible to vegetation modification had to develop new resource exploitation strategies to adapt to the change. Schlosseria magister considered as the direct ancestor of L. expeditus and having a low level of ecological flexibility, were unable to adapt to the habitat changes finally becoming extinct at ~45 Ma.