Shaximiao Formation, Jurassic fossil formation in Zigong, China

The Shaximiao Formation is a Jurassic rock layer in Sichuan Province, China, made up of purple-red mudstones and siltstones with sandstone beds in between. It holds a large number of dinosaur fossils along with remains of other creatures from that period.

The formation came to light in 1972 when construction work uncovered dinosaur bones at the site. Systematic excavations in the decades that followed turned it into one of the most important vertebrate fossil sites from the Jurassic period.

The Zigong Dinosaur Museum, built directly over the fossil site in the mid-1980s, holds most of the specimens excavated from the formation. It displays finds such as Gasosaurus, the first dinosaur uncovered here in 1972, and Dashanpusaurus dongi, named after the township of Dashanpu and paleontologist Dong Zhiming.

The fossil beds lie in and around Dashanpu township, about seven kilometres north-east of Zigong in Da'an District, and the Zigong Dinosaur Museum stands directly over the quarry where most specimens were excavated. The site itself is an active quarry, so visitors should confirm access and opening arrangements before travelling.

In some parts of the site, nearly complete dinosaur skeletons have been found, which is unusual for fossil deposits of this type. These complete skeletons allowed researchers to reconstruct the body shape and movement of species that elsewhere are known only from fragments.