Qualla: Yixian Formation

Yixian Formation: Introduction

Sat, 14 Mar 2026 00:00:00 GMT

Photo credit Dinolander, CC BY 4.0. In 1996, a farmer in Liaoning province split open a slab of rock and found a dinosaur with feathers. That single discovery -- Sinosauropteryx, the first non-avian dinosaur known to have had feathered integument -- was just the beginning. The Yixian Formation, a band of volcanic rock and lake sediments dating to the Early Cretaceous period, has since yielded the most revolutionary collection of fossils found anywhere in the world, fundamentally changing how scientists understand the relationship between dinosaurs and birds.

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Image: Dinolander | CC BY 4.0

Yixian Formation: China's Pompeii

Sat, 14 Mar 2026 00:00:00 GMT

Photo credit Didier Descouens, CC BY-SA 4.0. The Yixian Formation occupies the middle layer of the Jehol Group, sandwiched between the older Dabeigou Formation and the younger Jiufotang Formation. It formed roughly 125 million years ago during the Barremian to Aptian stages of the Early Cretaceous, in a landscape dominated ...

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Image: Didier Descouens | CC BY-SA 4.0

Yixian Formation: The Feathered Revolution

Sat, 14 Mar 2026 00:00:00 GMT

Photo credit PaleoEquii, CC BY-SA 4.0. Before the Yixian discoveries, the idea that dinosaurs had feathers was theoretical, based on skeletal similarities between small theropods and birds. The Yixian Formation turned theory into visible fact. Sinosauropteryx showed simple filamentous feathers. Beipiaosaurus, a theriz...

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Image: PaleoEquii | CC BY-SA 4.0

Yixian Formation: A Cretaceous Ecosystem Frozen in Time

Sat, 14 Mar 2026 00:00:00 GMT

Photo credit PaleoEquii, CC BY-SA 4.0. The Yixian was not just a dinosaur site. It preserved an entire ecosystem. Insects experienced their largest diversification of the Mesozoic era here. Five species of flowering plant -- among the earliest known angiosperms -- grew alongside ginkgoes, conifers, cycads, and seed fe...

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Image: PaleoEquii | CC BY-SA 4.0

Yixian Formation: Lost and Found

Sat, 14 Mar 2026 00:00:00 GMT

Photo credit He who needs to be silenced, CC0. The formation's scientific significance was first recognized during the Japanese occupation of China's Rehe Province after 1933, when Japanese researchers noticed fossil fish and reptile remains. Those initial collections vanished after World War II ended in 1945. Chinese scienti...

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Image: He who needs to be silenced | CC0