About 160 million years ago, in what is now northeastern China, a small feathered dinosaur lived among forests filled with early mammals, pterosaurs, and primitive bird relatives. It was named Serikornis sungei, meaning “silk bird,” for the soft, downy texture of its plumage.

The only known fossil was discovered in the Tiaojishan Formation of Liaoning Province and described in 2017 by paleontologist Ulysse Lefèvre and colleagues. Dating to the Late Jurassic, this fossil represents one of the earliest known members of the group that would eventually give rise to true birds. The species name honors Chinese paleontologist Sun Ge, who contributed to research in this region.

The fossil is exceptionally well preserved, showing every detail of its feathers and bones. Serikornis measured about 45 to 50 centimeters long, or roughly 18 to 20 inches, and weighed around 400 to 500 grams, about one pound. Its body was lightly built, with air spaces inside some of its neck bones that helped reduce weight.

Feathers covered nearly its entire body. Long feathers stretched along its arms, legs, and tail, creating the illusion of four wings. But Serikornis was not capable of flight. Its feathers lacked barbules, the microscopic hooks that hold feather strands together to form a smooth, aerodynamic surface. Without these hooks, the feathers were soft and loose, more suitable for insulation, display, or camouflage than for flying.

The tail carried two feather types: short filaments near the base and longer, symmetrical feathers toward the tip. The forelimbs had short vaned feathers, while the hind limbs bore longer ones that extended down to the toes. These feathers may have helped with controlled descents from low heights, but there is no clear evidence that Serikornis could glide or fly.

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Its skeleton shows several distinctive features. The upper jaw had four front teeth that were longer than the others. The shoulder girdle contained a coracoid bone with a small crest-like ridge. The pelvis ended in a narrow, hook-shaped projection. These traits help paleontologists identify its place in the evolutionary tree.

Serikornis belongs to the Anchiornithidae, a family of small feathered dinosaurs closely related to early birds but not yet capable of flight. It is part of the broader group Paraves, which also includes dromaeosaurids and troodontids, the closest relatives of birds. This makes it an important transitional species that shows feathers evolved for several functions long before flight existed.

The environment it lived in was warm and forested, with lakes and volcanic activity shaping the landscape. The Tiaojishan Formation has produced many other important fossils, including Anchiornis, Epidexipteryx, and some of the earliest mammals. In this habitat, Serikornis probably hunted small prey such as insects or lizards, moving quickly through undergrowth using its light body and strong legs.