The Yanliao Biota is the name given to an assembly of fossils preserved in northeastern China from the Middle to Late Jurassic.
Like the Jehol Biota, these deposits are composed of alternating layers of volcanic tuff and sediment, and are considered Lagerstätte.
These are some of the best preserved Jurassic fossils in the world, and include many important dinosaur, mammal, salamander, insect and lizard specimens, as well as plants.
The Yanliao Biota comes from outcrops north of the Han Mountains, in the northeast of the People's Republic of China.
The volcanic ash layers quickly buried the organisms, and created an anoxic environment around them, preventing scavenging and helping preserve them.