Yi qi

Chapter • Meet the dinosaur

Overview

Yi qi was a tiny feathered theropod, roughly pigeon-sized and weighing about 380 grams. Its fame rests entirely on its arms. From each wrist projected a long, rod-like bone – the so-called styliform element – unknown in any other dinosaur. Between that rod, the elongated fingers and the body stretched a membrane of soft tissue, preserved in the fossil as dark films around the arms. The rest of the body was covered in simple, bristle-like feathers. Yi qi therefore combined feathers with a skin wing rather like those of bats and pterosaurs, a combination found nowhere else among dinosaurs. Exactly how Yi qi moved through the air remains contested. The original 2015 description interpreted the membrane as a flying or gliding surface. A 2020 biomechanical study modelled the muscle attachments and wing area and concluded that powered flapping flight was almost certainly beyond it, leaving short glides between trees as the most plausible option. Its light build and strongly grasping hands fit a tree-dwelling animal that climbed up and glided down. Because only one specimen is known, every reconstruction carries real uncertainty. The teeth are small, procumbent and concentrated at the front of the jaws. Such teeth are usually read as an adaptation to a mixed diet of insects, grubs, small vertebrates, seeds and perhaps fruit or plant exudates. The close relative Ambopteryx even preserves gastroliths and bone fragments in its abdomen, supporting the view that scansoriopterygids were omnivores rather than pure predators. The holotype, specimen STM 31-2, was found by a farmer at Mutoudeng in Qinglong County, Hebei Province, China, and described in Nature in 2015 by Xu Xing, Zheng Xiaoting, Corwin Sullivan and colleagues. The name means roughly "strange wing" in Mandarin and is the shortest scientific dinosaur name on record. The fossil comes from the Tiaojishan Formation, the same beds that yielded Anchiornis and Epidexipteryx.

Chapter • Where it lived

Habitat

Yi qi lived about 160 million years ago in the later part of the Jurassic, in what is now north-eastern China. The only known skeleton comes from the Tiaojishan Formation at Mutoudeng, Qinglong County, Hebei Province. The setting was a humid, temperate landscape of conifer and ginkgo forest dotted with lakes and repeatedly buried by volcanic ash, whose fine grain preserved even soft tissue. Yi qi lived up among the trunks and branches alongside small feathered dinosaurs such as Anchiornis and Epidexipteryx.

Chapter • Wild behavior

Behavior & Ecology

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Chapter • Scientific place

Taxonomy