Epidexipteryx

Epidexipteryx is a bizarre, diminutive scansoriopterygid theropod recovered from the Late Jurassic Tiaojishan Formation of Inner Mongolia, China. Roughly the size of a pigeon, it lacks the flight feathers seen in dromaeosaurs, yet it features four elongated, ribbon-like tail plumes that were unmistakably evolved for visual communication or species recognition. Its short, tall skull held forward-pointing front teeth, which palaeontologists suspect were specialised for extracting beetle grubs and other wood-boring insects from tree bark. Although it was closely related to the membranous-winged glider Yi qi, Epidexipteryx lacked preserved wing membranes. Instead, it was probably an agile arboreal creature scampering along branches using its elongated manual digits. This extraordinary fossil shows that ornamental plumage developed remarkably early among non-avian theropods, functioning in courtship long before modern aerodynamic flight evolved.

It bore four remarkably long, ribbon-like tail feathers used for visual courtship display rather than for flight.

Where and when

Epidexipteryx lived in the Middle Jurassic, from 164 to 160 million years ago (Oxfordian age). Its remains come from China, in the Tiaojishan Formation.

The numbers

Length 0.3 m (estimates run from 0.25 to 0.3 m). Mass about 0.19 kg. Hip height about 0.1 m. That is 0.2 human-lengths, or 0.03 of a double-decker bus. These are estimates from near-complete skeleton; fields marked estimated by the site are length, mass, hip height.

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