The Yanliao Biota is the name given to an assembly of fossils preserved in northeastern China from the Middle to

Late Jurassic The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the nam ...

.Xu, X., Zhou, Z., Sullivan, C. and Wang, Y., 2017. The Yanliao Biota: a trove of exceptionally preserved Middle-Late Jurassic terrestrial life forms. Terrestrial Conservation Lagerstätten. Dunedin Academic Press, London, pp.131-167. It includes fossils from the

Tiaojishan Formation The Tiaojishan Formation is a geological formation in Hebei and Liaoning, People's Republic of China, dating to the middle-late Jurassic period ( Bathonian- Oxfordian stages). It is known for its exceptionally preserved fossils, including those o ...

, Lanqi Formation, Jiulongshan Formation and Haifanggou Formation. This spans approximately 199 to 146 million years ago. Like the Jehol Biota, these deposits are composed of alternating layers of volcanic tuff and sediment, and are considered

Lagerstätte A Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These for ...

. 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.

History

The first fossils of the Yanliao Biota were found around 1998 near the village of Daohugou in Inner Mongolia. The following year, the first two important specimens were discovered, and published in 2000. Since that time many more have been found from the same area, and in neighbouring provinces. The Yanliao Biota is made up of fossils from more than one locality, and the geology has been difficult to interpret (see below). It includes what was previously referred to as the Daohugou Biota,Sullivan C, Wang Y, Hone DWE, Wang Y, Xu X & Zhang F. 2014. The vertebrates of the Jurassic Daohugou Biota of northeastern China. ''Journal of Vertebrate Paleontology'', 34:2, 243-280, DOI: 10.1080/02724634.2013.787316 and some of it was thought to belong to the Jehol Biota.

Location

The Yanliao Biota comes from outcrops north of the Han Mountains, in the northeast of the

People's Republic of China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones an ...

. The most important site is near Daohugou Village in Inner Mongolia, but fossils and outcrops are also found in neighbouring Liaoning Province and Heibei Province.

Geology

The Dauhugou locality lies in the Ningchen Basin in the SE corner of Inner Mongolia. Dauhugou village has fossil-bearing lacustrine (laid down in lakes) strata overlying

precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of t ...

basement.

Fossil preservation

The formations that yield the fossils of the Yanliao Biota are known as ''

'', meaning that they have exceptionally good conditions for fossil preservation. The fossils are not only numerous, but also very well preserved. For vertebrates, there are often whole skeletons with soft tissues like skin and fur, colour patterns, and stomach contents. Insects are intact with wings and patterns preserved, and plants have their leaves and flowers still attached. The volcanic ash layers quickly buried the organisms, and created an anoxic environment around them, preventing scavenging and helping preserve them.

Fossils

Dinosaurs

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Anchiornis huxleyi ''Anchiornis'' is a genus of small, four-winged paravian dinosaurs, with only one known species, the type species ''Anchiornis huxleyi'', named for its similarity to modern birds. The Latin name ''Anchiornis'' derives from a Greek word meaning " ...

'' *'' Epidendrosaurus ningchengensis'' *'' Epidexipteryx hui'' *'' Pedopenna daohouensis'' *'' Xiaotingia shengi'' *''

Aurornis xui ''Aurornis'' is an extinct genus of anchiornithid theropod dinosaurs from the Jurassic period of China. The genus ''Aurornis'' contains a single known species, ''Aurornis xui'' (). ''Aurornis xui'' may be the most basal ("primitive") avialan di ...

'' *''

Eosinopteryx brevipenna ''Eosinopteryx'' is an extinct genus of theropod dinosaurs known to the late Jurassic period of China. It contains a single species, ''Eosinopteryx brevipenna''. Discovery and naming ''E. brevipenna'' is known from a single fossil specimen reco ...

'' *'' Tianyulong confuciusi''