Yixian Formation
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Yixian_Formation".

The Yixian Formation is a geological formation in Jinzhou, Liaoning, People's Republic of China, that stems from the early Cretaceous period. It is known for its fossils. It was initially recognized during the time the Japanese Empire controlled a large chunk of Manchuria (Northern China) called "Jehol". During the occupation of Jehol, many Japanese scientists had noticed fossil remains of extinct fish and reptiles, possibly the champsosaurs. These initial fossil discoveries made by Japanese scientists vanished from history once World War II ended in 1945. By 1949, when administration of the area passed to the Communist Party and its leader Mao Zedong, the fossils of Yixian were studied only by Chinese scientists. It was not until the 1990s when remarkable fossils of birds and dinosaurs were excavated. Since 1996, a number of dinosaur fossils that have revolutionized knowledge of these animals have been found at Yixian; among them are the first known non-avian theropods with feathers. See Jehol Biota.

For some time, the formation was believed to be from the Late Jurassic-Early Cretaceous boundary, some 145 mya (million years ago). Radiometric dating has since resolved it to be younger; it is now considered to have been deposited in the Barremian to early Aptian, some 125-121 mya.[1]

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Fossil taxa

Fossils found in the Yixian Formation include:

Dinosaurs (including birds)

Theropods

Cerapods

Thyreophorans

Pterosaurs

Mammals

Symmetrodonts

Triconodonts

Multituberculates

Metatheria (marsupials)

Eutheria (placental mammals)

Other vertebrates

Lepidosaurians

Choristoderans

Turtles

Amphibians

Fish

Insects and other arthropods

Fossil of Archaefructus, an extinct genus aquatic plants, found at the Yixian Formation.
Fossil of Archaefructus, an extinct genus aquatic plants, found at the Yixian Formation.

Plants

See also

References

  1. ^ Swisher, Carl C., Wang, Yuan-qing, Wang, Xiao-lin, Xu, Xing, Wang, Yuan. (1999). "Creatceous age for the feathered dinosaurs of Liaoning, China". Nature 400:58-61 1 July 1999.
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