Epidexipteryx

Chapter • Meet the dinosaur

Overview

Epidexipteryx hui is one of the smallest dinosaurs known. Its body measured only about 25 centimetres, and with the four long, ribbon-like tail feathers included the total length reached roughly 44.5 centimetres. Published mass estimates are around 160–200 grams, less than a pigeon. The skull was short and deep with a blunt snout, and the front of the jaws carried unusually large, forward-angled teeth – a feature almost unique among theropods. Simple, shaft-less down-like feathers covered the body, while the four elongate tail feathers had a broad stiff central portion built in a way seen in no living bird. Epidexipteryx belonged to the scansoriopterygids, a small and highly unusual group of maniraptoran theropods. The forelimbs were long and the third finger was elongated, a condition that in relatives such as Scansoriopteryx and Yi qi has been linked to climbing or to supporting a membranous wing. In Epidexipteryx no long pennaceous feathers are preserved on the arms, and the animal almost certainly could not fly. The tail feathers were far too slender to work aerodynamically and are instead interpreted as display structures, comparable to the ornamental tail plumes of some modern birds. That makes Epidexipteryx one of the oldest known examples of feathers used for signalling rather than for flight or insulation. The enlarged front teeth, short jaws and tiny body point to a diet of insects, grubs and other small invertebrates, perhaps supplemented with small vertebrates, eggs, fruit or tree sap. Some researchers have compared the dentition to that of modern animals that gouge bark to reach insects and sap, but no gut contents are preserved, so the diet remains a well-reasoned inference rather than an established fact. The species was described in 2008 by Zhang Fucheng, Zhou Zhonghe, Xu Xing, Wang Xiaolin and Corwin Sullivan in Nature. The single known specimen, holotype IVPP V 15471, comes from the Daohugou beds of Ningcheng in Inner Mongolia, China. The genus name means roughly "display feather", and the species name hui honours the Chinese palaeontologist Hu Yaoming, who died shortly before the fossil was published. The find drew immediate attention because it showed that ornamental feathers already existed in the Jurassic, long before the rise of modern birds.

Chapter • Where it lived

Habitat

Epidexipteryx lived roughly 165–160 million years ago, in the Middle to Late Jurassic, in what is now Inner Mongolia in northern China. The only known fossil comes from the Daohugou beds at Daohugou, Ningcheng, generally referred to the Tiaojishan Formation. The setting was a humid, temperate landscape of conifer and ginkgo forests around lakes, dusted repeatedly by ash from nearby volcanoes. The fine lake sediments preserved soft tissue and feathers in remarkable detail, and the same beds have yielded salamanders, insects, early mammals and the feathered relatives Epidendrosaurus and Pedopenna. The densely forested environment fits well with the idea that Epidexipteryx spent at least part of its time in trees.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy