Episode 152 – The Jehol Biota

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For the last few decades, a seemingly non-stop stream of famous fossils have been produced by excavations in China, and most of them are coming from the same region. This episode, we discuss the deep history, the incredible fossils, and the abundant research opportunities of the Jehol Biota.

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Very Famous Fossils

The Jehol Biota is a diverse fossil ecosystem from the Early Cretaceous of northeastern China. The Biota (this word refers to the fossils themselves) includes plants and animals from the Jiufotang, Yixian, and Huajiying Formations, as well as some other nearby fossil deposits, depending on the definition you’re using. The fossils range from 135-110 million years old, and they include some of the most well-preserved and most famous fossils ever found.

Fossils of the Jehol Biota are commonly preserved in ashy lake sediments which can provide incredibly complete specimens. These are just a few examples.
Top left: The fish Lycoptera. Image from Dwergenpaartje, CC BY-SA 3.0
Top right: The dinosaur Sinosauropteryx. Image from Sam, CC BY-SA 2.0
Bottom left: The scorpionfly Jeholopsyche. Image from Ren et al. 2011, CC BY 3.0
Bottom right: The dinosaur Psittacosaurus. Image from Vinther et al. 2016

Some of the earliest fossils to be scientifically described from the Jehol Biota were fish, insects, and other invertebrates identified in the 1800s and early 1900s. In the 1990s, the Jehol region became world-famous with the discovery of the world’s first feathered non-bird dinosaurs. Since then, the Jehol Biota has produced a long list of incredible fossils that have made headlines, such as Sinosauropteryx, the first dinosaur found with feathers and one of the first dinosaurs to have its coloration determined; Yutyrannus, a feathered tyrannosaur and the largest feathered animal ever discovered; Repenomamus, the first Mesozoic mammal ever known to have eaten dinosaurs; Archaefructus, which might be one of the oldest known flowering plants; and that famous specimen of Psittacosaurus which preserves everything from quills to colors to cloaca; just to name a few!

Jehol fossils often preserve exquisite details of soft tissues.
Top left: Tail feathers of the dinosaur Sinosauropteryx; Top right: Flight feather of the bird Confuciusornis
Bottom left: Skin of the lizard Liushusaurus; Bottom right: Eyes, muscles, and gonads of the lamprey Mesomyzon. Images from Zhou 2014

Hundreds of fossil species have been identified among the Jehol Biota, including plants, invertebrates, and vertebrates, providing excellent resources for studies on insects, early birds, early flowering plants, pterosaurs, and more. The preservation of soft tissues and minute details makes these fossils invaluable for research into the evolution, lifestyles, and anatomy of these groups.

Jehol fossils are famous (among all the other reasons) for well-preserved gut contents and embryos, providing incredible insights into the diets and reproduction of fossil animals.
Top left: Seeds in the stomach of the bird Jeholornis; Top right: Gizzard stones in the stomach of the bird Archaeorhynchus; Bottom left: Embryo of an enantiornithine bird; Bottom right: Embryo of a pterosaur.
Images from Zhou 2014
Gut contents are so common in the Jehol Biota, in fact, that one study was able to put together this diagram of the Jehol food web, including 20 different examples of who was eating who! At the top of the diagram (A) are examples from the Yanliao Biota, while the examples in (B) are all from the Jehol Biota. Image from O’Connor et al. 2019

Learn More

Zhou 2014. Overview of Jehol Biota discoveries. (Technical, open access)
Xu et al 2021. A more recent review. (Technical, paywall)

O’Connor et al 2019. Microraptor gut contents and the Jehol Biota food web. (Technical, open access)

Zhang et al 2010. Evolution of insect diversity in the Jehol Biota (technical, open access)

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