[Paleontology • 2015]
Yi qi • A Bizarre Jurassic Maniraptoran Theropod with preserved Evidence of Membranous Wings
|Yi qi | ‘ee chee’ |
Xu, Zheng, Sullivan, Wang, Xing, Wang, Zhang, O’Connor, Zhang & Pan, 2015
The wings of birds and their closest theropod relatives share a uniform fundamental architecture, with pinnate flight feathers as the key component. Here we report a new scansoriopterygid theropod, Yi qi gen. et sp. nov., based on a new specimen from the Middle–Upper Jurassic period Tiaojishan Formation of Hebei Province, China. Yi is nested phylogenetically among winged theropods but has large stiff filamentous feathers of an unusual type on both the forelimb and hindlimb. However, the filamentous feathers of Yi resemble pinnate feathers in bearing morphologically diverse melanosomes. Most surprisingly, Yi has a long rod-like bone extending from each wrist, and patches of membranous tissue preserved between the rod-like bones and the manual digits. Analogous features are unknown in any dinosaur but occur in various flying and gliding tetrapods, suggesting the intriguing possibility that Yi had membranous aerodynamic surfaces totally different from the archetypal feathered wings of birds and their closest relatives. Documentation of the unique forelimbs of Yi greatly increases the morphological disparity known to exist among dinosaurs, and highlights the extraordinary breadth and richness of the evolutionary experimentation that took place close to the origin of birds.
|The dinosaur would have sported a robust skull with a short snout|
photo: Zang Hailong
Theropoda Marsh, 1881
Maniraptora Gauthier, 1986
Scansoriopterygidae Czerkas et Yuan, 2002
Yi qi gen. et sp. nov.
Etymology. The generic and specific names are derived from Mandarin Yi (wing) and qi (strange), respectively, referring to the bizarre wings of this animal. The intended pronunciation of the name is roughly “ee chee”.
Holotype. STM 31-2 (housed at the Shandong Tianyu Museum of Nature), an articulated partial skeleton with associated soft tissue preserved on a slab and counter slab. The specimen was collected by a local farmer, but its provenance and authenticity have been confirmed by multiple lines of evidence including sedimentology, taphonomy and computed tomography (CT) data.
Locality and horizon. Mutoudeng, Qinglong County, Hebei Province, China. Tiaojishan Formation, Callovian–Oxfordian stage. On the basis of the provenance of the specimen, Yi qi is a member of the Daohugou (or Yanliao) Biota.
features of the "winged" dinosaur fossil reveal feathers over the neck
(not shown), along the humerus (b) and along the humerus and ulna (c).
The fossil also showed soft tissue and feathers along the right forelimb
and hindlimb. |
photo: Zang Hailong | doi:10.1038/nature14423
Xing Xu, Xiaoting Zheng, Corwin Sullivan, Xiaoli Wang, Lida Xing, Yan Wang, Xiaomei Zhang, Jingmai K. O’Connor, Fucheng Zhang and Yanhong Pan. 2015. A Bizarre Jurassic Maniraptoran Theropod with preserved Evidence of Membranous Wings.
Nature. doi: 10.1038/nature14423
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