The Lantian Formation is a 150-meter-thick sequence of rocks deposited in Xiuning County, Anhui Province in southern China during a 90-million-year epoch in the Ediacaran period.

[2] Its algal macrofossils (which have alternatively been interpreted as putative metazoans[3]) are the oldest large and complex fossils known.

[2] The rocks were deposited in shallow seas, in the photic zone yet below storm wave base[clarification needed],[4] yet were deposited in predominantly anoxic conditions.

[2] The lowest part of the formation consists of a cap dolomite, marking the end of the Marinoan glaciation and start of the Ediacaran.

[4] The Lantian biota has a maximum Re-Os age of 602 ± 7 million years ago.