What is Scansoriopterygidae?

The least inclusive clade including Epidendrosaurus (=Scansoriopteryx) and Epidexipteryx. Scansoriopterygids were sparrow- to pigeon-sized maniraptoran dinosaurs that lived in the Middle to Late Jurassic forests of what is now northeastern China. Their fossils, preserved in fine volcanic ash beds, reveal a group of dinosaurs that took to the trees long before birds perfected powered flight.

These dinosaurs had long arms, grasping hands, and an exceptionally elongated third finger—a feature not seen in any other dinosaur group. In the earliest known members, such as Scansoriopteryx and Epidexipteryx, this long finger likely helped them climb and cling to branches, while their bodies were covered in simple feathers. Some species also carried long ribbon-like tail feathers, probably used for display.

Later scansoriopterygids, including Yi and Ambopteryx, pushed arboreal experimentation even further. They evolved a membranous wing, supported by both the long third finger and a unique styliform bone projecting from the wrist. This structure formed a gliding surface more like that of a bat or flying squirrel than a bird. These wings represent a separate evolutionary experiment in aerial locomotion, unrelated to the feathered wings that eventually led to birds.

Although short-lived in evolutionary terms, Scansoriopterygidae capture a moment of remarkable innovation—tiny dinosaurs testing the possibilities of life in the canopy, each species exploring a different path toward the air.

Click here to search Dinochecker for scansoriopterygids. Scansoriopterygidae is derived from the Latin "scandere" (climb), the Greek "pteryx" (wing), and the Latin "-idae" (family).