“…Here the Shangcun Formation consists mainly of gray-green to gray-white mudstones, shales, argillaceous siltstones and dark brown oil shales intercalated with calcareous siltstones and lignites ( BGMRGD, 1988 ). This formation contains gastropods, fish, and abundant well-preserved plant fossils representing the families Osmundaceae, Polypodiaceae, Pinaceae, Cupressaceae, Platanaceae, Lauraceae, Fagaceae, Malvaceae, Juglandaceae, Myricaceae, Simaroubaceae, and Palmae ( Herman et al., 2017 ; Kodrul et al., 2018 ; Wu et al., 2019b ; Xu et al., 2021 ). The age of the Shangcun Formation has been assigned to the early Oligocene based on palynological and magnetostratigraphic studies ( Wang et al., 1994 ; Herman et al., 2017 ).…”