The Jehol Biota

Across the Dabeigou, Yixian and Jiufotang formations of northeastern China, repeated falls of fine volcanic ash into quiet lakes entomb an entire Early Cretaceous world between roughly 131 and 120 million years ago. The preservation is extraordinary: feathers with their pigment-bearing melanosomes intact, mammal fur, insect wings, flowers, gut contents and even last meals. More than any other deposit, Jehol converted the dinosaur-bird link from a skeletal argument into something you can look at, and it is the single richest source of what we now know about feathers before flight.