Siberian Jehol Biota

Volcanogenic-sedimentary and coal-bearing deposits, which contain abundant fossils of a lacustrine fauna and terrestrial flora, are widespread in the territory of Transbaikalia (Russia), Mongolia, and Northeastern China. These ecosystems are known under the name of ‘Jehol Biota’, which occurs in the Yixian and Jiufotang formations. The discovery of ‘feathered’ dinosaurs and of the earliest angiosperms in western Liaoning Province (China) made them world famous. The history of this biota began in the nineteenth century, when the discoveries in Transbaikalia of the remains of conchostracans, ostracods, insects, fish, and plants collected during the expedition of A.F. Middendorf were described. The Barremian–Aptian sedimentary sequences of Transbaikalia (Russia), Mongolia, and Northeastern China are very similar. The appearance and evolution of the Jehol Biota occurred against the background of extensive volcanism and tectonic revival, after which normal sedimentary rocks were deposited, culminating in relief peneplanation, swamp development and peat formation. The northern limit of the distribution of this biota is determined as up to about 54° modern north latitude. The existence of the Siberian Jehol Biota in extreme climatic conditions is confirmed, as was indicated for the Jehol Biota from Northeast China.