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An exceptionally well-preserved theropod dinosaur from the Yixian Formation of China
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Pei-ji Chen*, Zhi-ming Dong & Shuo-nan Zhen* Nanjing Institute of Geology and Palaeontology, Academia Sinica, 39 East Beijing Road, Nanjing 210008, Peoples Republic of China Institute of Vertebrate Paleontology and Paleoanthropology, Academia Sinica, PO Box 643, Beijing 100044, Peoples Republic of China Beijing Natural History Museum, 126 Tien Qiao Street, Beijing 100050, Peoples Republic of China
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Two spectacular fossilized dinosaur skeletons were recently discovered in Liaoning in northeastern China. Here we describe the two nearly complete skeletons of a small theropod that represent a species closely related to Compsognathus. Sinosauropteryx has the longest tail of any known theropod, and a three-ngered hand dominated by the rst nger, which is longer and thicker than either of the bones of the forearm. Both specimens have interesting integumentary structures that could provide information about the origin of feathers. The larger individual also has stomach contents, and a pair of eggs in the abdomen.
The Jehol biota1 was widely distributed in eastern Asia during latest Jurassic and Early Cretaceous times. These freshwater and terrestrial fossils include macroplants, palynomorphs, charophytes, agellates, conchostracans, ostracods, shrimps, insects, bivalves, gastropods, sh, turtles, lizards, pterosaurs, crocodiles, dinosaurs, birds and mammals. In recent years, the Jehol biota has become famous as an abundant source of remains of early birds2,3. Dinosaurs are less common in the lacustrine beds, but the specimens described here consist of two nearly complete skeletons of a small theropod discovered by farmers in Liaoning. The skeletons are from the basal part of the Yixian Formation, from the same horizon as the fossil birds Confuciusornis and Liaoningornis3. Both are remarkably well preserved, and include fossilized integument, organ pigmentation and abdominal contents. One of the two was split into part and counterpart, and the sections were deposited in two different institutions. One side (in the National Geological Museum of China, Beijing) became the holotype of Sinosauropteryx prima, a supposed bird4. The counterpart and the second larger specimen are in the collections of the Nanjing Institute of Geology and Palaeontology.
The Yixian Formation is mainly composed of andesites, andesite-
breccia, agglomerates and basalts, but has four fossil-bearing sedimentary intercalations that are rich in tuffaceous materials. The Jianshangou (formerly Jianshan5,6)...