Description of a new enantiornithine bird from the Early Cretaceous of Hebei, northern China Fucheng Zhang, Per G.P. Ericson, and Zhonghe Zhou Abstract: This paper describes a new enantiornithine fossil bird, Vescornis hebeiensis, nov. sp. from the Early Cretaceous of China. We refer Vescornis to the crown clade Euenantiornithes based on several characteristics observed in the thoracic girdle and wing. Vescornis also exhibits characteristics that separate it from other enantiornithine birds, such as the short alular phalanx, the vestigial manual claws, and the well-developed and long foot claws. These features suggest an adaptation towards an improved flight capability, while the ability of Vescornis to climb is reduced compared with many other enantiornithine birds. Résumé : Cet article décrit un nouvel oiseau fossile, Vescornis hebeiensis, sp. nov. (groupe des Enantiornithes), du Crétacé précoce en Chine. Nous référons Vescornis au clade maître Euenantiornithes d’après plusieurs caractéristiques observées dans la ceinture thoracique et les ailes. Vescornis démontre aussi des caractéristiques qui le distinguent des autres oiseaux du groupe des Enantiornithes : la courte phalange de l’alula, les griffes manuelles atrophiées et les griffes longues et bien développées des pieds. Ces caractéristiques suggèrent une adaptation à une meilleure capacité de vol alors que l’habilité de Vescornis à grimper est réduite si on la compare à de nombreux autres oiseaux du groupe des Enantiornithes. [Traduit par la Rédaction] Zhang et al. 1107 Introduction From an evolutionary perspective, birds (Class Aves) consist of several large clades, of which only one, Ornithurae, has survived to recent time (Martin 1983; Zheng 1995; Feduccia 1999). Several distinct groups of birds became extinct during the Late Cretaceous, not necessarily at the K–T boundary, as was the case in many other categories of organisms. One of these, and probably the most successful as judged from the fossil record, was the enantiornithine birds. The enantiornit- hines may have been the geographically most widespread, the taxonomically and ecologically most diverse, and, possibly, the most abundant group of birds in the Mesozoic (e.g., Chiappe 1995; Feduccia 1999; Zhang et al. 2001). The members of this group seem most often to have occupied terrestrial habitats, but they are also known from marine environments (Chiappe et al. 2002). Several enantiornithine birds have been described from Early Cretaceous formations in China (Wang et al. 2000), most notably the Jiufotang Formation (Sinornis, Cathayornis, Boluochia, Cuspirostrisornis, Eocathayornis, Largirostrornis, Longchengornis, Longipteryx) and the Yixian Formation (Eoenantiornis, Liaoxiornis, Longirostravis) in the Liaoning Province in the northeastern part of the country (Sereno and Rao 1992; Zhou 1995; Hou 1997; Hou and Chen 1999; Hou et al. 1999; Zhang et al. 2001; Zhou 2002; Hou et al. 2004). Herein, we describe a new enantiornithine bird from the northern Hebei Province, China (Fig. 1). It comes from the Early Cretaceous Yixian Formation, (Wang et al. 2000). Among vertebrates, the bird-bearing sediments have mostly yielded fish remains, and the number of bird fossils col- lected so far is rather low—the described avian taxa from the deposits are Jibeinia luanhera (Hou 2000) and Protopteryx (Zhang and Zhou 2000). The correlations of the deposits in Hebei and Liaoning are mainly based on biostratigraphic comparisons, yet there is no isotope dating supporting the correlations. Systematic palaeontology Aves Linnaeus, 1758 Enantiornithes Walker, 1981 Euenantiornithes Chiappe, 2002 Vescornis hebeiensis, nov. sp. ETYMOLOGY: The genus name “Vescornis” is derived from the Latin prefix “vesc” (thin, attenuated), indicating the short and undeveloped alular digit and other ungual phalanges of Can. J. Earth Sci. 41: 1097–1107 (2004) doi: 10.1139/E04-055 © 2004 NRC Canada 1097 Received 6 January 2004. Accepted 24 June 2004. Published on the NRC Research Press Web site at http://cjes.nrc.ca on 20 September 2004. Paper handled by Associate Editor H.-D. Sues. Fucheng Zhang 1 and Zhonghe Zhou. Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, P.O. Box. 643, Beijing 100044, P.R. China. Per G.P. Ericson. Department of Vertebrate Zoology, Swedish Museum of Natural History, P.O. Box 50007, SE-104 05 Stockholm, Sweden. 1 Corresponding author (email: fuchengzhang@yeah.net).