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467 26 A New Basal Ornithomimosaur (Dinosauria: Theropoda) from the Early Cretaceous Yixian Formation, Northeast China Jin Liyong, Chen Jun, and Pascal Godefroit* We describe a new basal Ornithomimosauria from a specimen (JLUMJZ07b1 ) discovered in the lowest beds (Lower Valanginian–Lower Barremian , Lower Cretaceous) of the Yixian Formation in western Liaoning province, P.R. China. Hexing qingyi gen. et sp. nov. is characterized by a series of cranial and postcranial autapomorphies: the rostral portion of the premaxilla deflected ventrally in front of the lower jaw, so that its oral surface is level with the ventral border of the dentary, a deep antorbital fossa that invades the whole lateral surface of the maxilla, a sagittal crest on the parietal, pendant paroccipital processes that extend ventrally below the level of the foramen magnum, a dentary fenestra, a phalangeal formula for manus of 0-(1 or 2)-3-3-0, and elongated (>85% length of corresponding metacarpal) proximal phalanges of digits III and IV. A phylogenetic analysis shows that Hexing is a basal ornithomimosaur more derived than Pelecanimimus but basal to Harpymimus, Beishanglong, and the edentulous clade formed by Garudimimus and the Ornithomimidae. Incomplete overlap between preserved body parts across specimens prevents full resolution of the relationships between Hexing, Shenzhousaurus (also from the Yixian Formation of western Liaoning province), and more advanced ornithomimosaurs . Ornithomimosauria had an extensive evolutionary history in eastern Asia from the Valanginian–Barremian, until the early Maastrichtian, and a single dispersal across the Bering Strait is required to account for the distribution of advanced Ornithomimidae in Asia and North America. Ornithomimosauria (ostrich-mimic dinosaurs) is a group of lightly built and cursorial theropods that are mainly known from Cretaceous localities of Asia and North America (Makovicky et al., 2004). Although phylogenetically nested among carnivorous theropods, advanced Ornithomimidae lack teeth but had beaks and gastoliths (Kobayashi et al., 1999), suggesting that their diet was completely different from that of typical theropods. Ornithomimosauria have been viewed as carnivores of small prey, insectivores, and even herbivores (Nicholls and Russell, 1981; Kobayashi et al., 1999; Makovicky et al., 2004; Barrett, 2005). They may have exhibited gregarious habits (Kobayashi and Lü, 2003; Varricchio et al., 2008). Thousands of exceptionally preserved dinosaurs, birds, early mammals, amphibians, aquatic reptiles, pterosaurs, flowering plants, and insects have been unearthed during the last 15 years in western Liaoning province and constitute the famous Early Cretaceous Jehol Biota. Among dinosaurs, Introduction Jin et al. 468 feathered theropods from the Jehol Biota have received particular attention , allowing for the reconstruction of the early evolution of feathers and flight as well as reconstruction of the phylogenetic relationships between coelurosaurian dinosaurs and birds. Ji et al. (2003) described Shenzhousaurus orientalis, the oldest known Ornithomimosauria, from the lowest more fluvial, volcanoclastic beds of Yixian Formation (Lower Valanginian–Lower Barremian; Swisher et al., 2002). Here, we describe a second ornithomimosaur from the same beds. As it is usually the case for fossils discovered in the Yixian Formation, this specimen was discovered by a local farmer, who began its preparation. The fossil was subsequently carefully prepared in the laboratory of the Geological Museum of Jilin University. All the dubious parts of the skeleton, which may have been affected by the preparation of the local farmer, have been removed and are not included in the following description. Institutional abbreviations. CMN, Canadian Museum of Nature, Ottawa, Canada; JLUM, Geological Museum of the Jilin University, Changchun, P.R. China. Dinosauria Owen, 1842 Theropoda Marsh, 1881 Tetanurae Gauthier, 1986 Coelurosauria von Huene, 1914 Ornithomimosauria Barsbold, 1976 Hexing qingyi gen. et sp. nov. (Figs. 26.1–26.7) Etymology. From Mandarin, Hexing, “like a crane,” and quingyi, “with thin wings.” Holotype. JLUM-JZ07b1, housed in the Geological Museum of the Jilin University, Changchun (Jilin province, P.R. China). Locality and horizon. Xiaobeigou locality, Lujiatun, Shangyuan, Beipiao City, western Liaoning province, P.R. China; lowest more fluvial, volcanoclastic beds of Yixian Formation, older than 128 million years and younger than 139 million years (Lower Valanginian–Lower Barremian; Swisher et al., 2002). Diagnosis. Ornithomimosauria with the following autapomorphies: rostral portion of premaxilla deflected ventrally in front of lower jaw, so that its oral surface is level with the ventral border of dentary; deep antorbital fossa invades the whole lateral surface of maxilla; sagittal crest on parietal; pendant paroccipital processes that extend ventrally below the level of the foramen magnum; dentary fenestra; phalangeal formula for manus: 0-(1 or 2)-3-3-0; proximal phalanges of manus digits III and IV elongated (> 75% length of...

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