The Lantian Formation is an Ediacaran aged geologic formation in Xiuning County, Anhui Province of South China. The formation contains the Lantian Biota, a collection of large macrofossils, including putative cnidarian-grade fossils, which where previously the oldest macrofossils until the discovery of the Ancanping Assemblage in older rocks of the Doushantuo Formation.
Sedimentology The rocks were deposited in shallow seas, in the photic zone yet below storm wave base, yet were deposited in predominantly anoxic conditions. The fossils are located on the bedding planes, and are randomly oriented.
The lowest part of the formation consists of a cap dolomite, marking the end of the Marinoan glaciation and start of the Ediacaran. Above this is black shale containing the Lantian biota fossils. Above this are layers of dolomite, and shale followed by limestone. The highest part of the formation is black shale again. Above the formation is the Piyuancun formation consisting of silicious rock. The Lantian formation overlies diamictite from the Cryogenian.supplementary figure 4 of
Taphonomy The fossils are preserved as carbonaceous films in a Burgess Shale type preservational fashion. Anhuiphyton lineatum is one example of a fossil located in the site.
Age Originally presumed to be Cambrian in age, the formation is now correlated with the Doushantuo Formation, with an overlying formation also falling in the Ediacaran period.
The Lantian biota has a maximum Re-Os age of .
Paleobiota The Lantian Formation is home to the Lantian Biota, which was previously the oldest known macroscopic biota before the discovery of the lower Doushantuo Formation macrofossils. This biota is predominately composed of algae forms, although contains a sparse record of metazoan fossils, such as the palaeopascichnid organism Orbisiana, and putative cnidarian-like organisms such as Lantianella and Piyuania.
Algae
GenusSpeciesNotesImagesChuariaC. circularisEnigmatic fossil, possibly synonymous with Tawuia.DoushantuophytonD. cometaBranching macroalgae.HuangshanophytonH. fluticulosumMacroalgae.AnhuiphytonA. lineatumMacroalgae.FlabellophytonF. lantianensis F. strigata Flabellophyton sp.Macroalgae.
incertae sedis
GenusSpeciesNotesImagesOrbisianaOrbisiana sp.Palaeopascichnid organism.LantianellaL. laevis L. annularisCnidarian-grade fossil.PiyuaniaP. cyathiformisCnidarian-grade fossil.QianchuaniaQ. fusiformisCnidarian-grade fossil.XiuningellaX. raraCnidarian-grade fossil.
References