Ether lipids from the Lower and Middle Triassic at Qingyan, Guizhou Province, Southern China

► Ether lipids occur in Lower-Middle Triassic sediments (Qingyan, Guizhou Province, SW China). ► Represent oldest occurrence of such lipids, including archaeol and non-isoprenoid DAGEs and MAGEs). ► Archaeol derives from archaea and DAGEs and MAGEs are likely from sulfate-reducing bacteria (SRB). ► SRB might have contributed to a contemporaneous euxinic ocean in the Early Triassic. Ether lipids such as non-isoprenoid mono and dialkyl glycerol ethers (MAGEs and DAGEs) and archaeol have been found in carbonate rocks and mud rocks deposited during the Early and Middle Triassic (250–240Ma). The oldest previous discovery of ether lipids is from Cretaceous black shale deposited during the Albian (112Ma). Paleoenvironmental reconstruction using ether lipids has therefore not been conducted on pre-Cretaceous sediments. Archaeol derives from archaea (e.g. methanogenic, methanotrophic, halophilic and thermophilic archaea). The non-isoprenoid DAGEs and MAGEs likely derive from sulfate-reducing bacteria (SRB), which are restricted to anaerobic environments. The presence of ether lipids thus indicates that anoxic conditions expanded in the depositional and/or water column environment in the Qingyan area during the Early–Middle Triassic. These ether lipids may be useful for the reconstruction of paleoredox conditions and paleoecosystems in the area. Furthermore, their occurrence suggests that paleoenvironmental reconstruction using ether lipids may be possible throughout the Mesozoic and Cenozoic.