A bizarre Jurassic maniraptoran theropod with preserved evidence of membranous wings.
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.
1] Institute of Geology and Paleontology, Linyi University, Linyi City, Shandong 276005, China [2] Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.
Xing
X
Xu
1] Institute of Geology and Paleontology, Linyi University, Linyi City, Shandong 276005, China [2] Shandong Tianyu Museum of Nature, Pingyi, Shandong 273300, China.
Xiaoting
X
Zheng
Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.
Corwin
C
Sullivan
Institute of Geology and Paleontology, Linyi University, Linyi City, Shandong 276005, China.
Xiaoli
X
Wang
School of the Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China.
Lida
L
Xing
Institute of Geology and Paleontology, Linyi University, Linyi City, Shandong 276005, China.
Yan
Y
Wang
Shandong Tianyu Museum of Nature, Pingyi, Shandong 273300, China.
Xiaomei
X
Zhang
Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.
Jingmai K
JK
O'Connor
Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China.
Fucheng
F
Zhang
Key Laboratory of Economic Stratigraphy and Palaeogeography of Chinese Academy of Sciences, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
Yanhong
Y
Pan
D000818:Animals; D001717:Birds / Q000145:classification; D002681:China; D025061:Dinosaurs / Q000033:anatomy & histology* / Q000145:classification*; D005241:Feathers / Q000033:anatomy & histology; D005580:Fossils; D010802:Phylogeny; D014921:Wings, Animal / Q000033:anatomy & histology*