A Strange Wing from the Jurassic
In 2007, a farmer named Wang Jianrong discovered a fossil in a quarry near Mutoudeng Village in China's Hebei Province. He sold it to the Shandong Tianyu Museum of Nature, where technicians began the careful work of preparing the single, remarkable specimen. What they revealed was a pigeon-sized dinosaur from the mid-to-late Jurassic Period, approximately 159 million years ago. Its scientific name, Yi qi, is the shortest of any dinosaur and means "strange wing" in Mandarin.
The strangeness comes from its wings. Unlike any other known dinosaur, Yi qi's wings were not made of feathers but of skin, similar to a bat's. This membrane was stretched between its fingers and a unique, rod-like bone extending from its wrist called a styliform element. This bone is not found in any other dinosaur but is convergent evolution, with similar structures appearing in gliding animals like bats and flying squirrels. The single known fossil, catalogued as STM 31-2, shows the partial skeleton of an adult estimated to have weighed about 380 grams (0.84 lb). The fossil also preserved impressions of wrinkled skin between the fingers and the styliform bone, confirming the membranous wing structure.