Читать книгу Hadrosaurs - David A. Eberth - Страница 113

After nearly 100 years of scientific exploitation, the Upper Cretaceous rocks of the Gobi Desert in southern Mongolia continue to yield new and unusual dinosaur taxa. In the last decade alone over a dozen new taxa have been named – including the theropods Tsaagan, Mahakala, and Kol; and the ceratopsians Bainoceratops, Yamaceratops, and Gobiceratops (Norell et al., 2006; Turner et al., 2007, 2009; Tereschenko and Alifanov, 2003; Makovicky and Norell, 2006; Alifanov, 2008, respectively). Ornithopods are considerably less diverse in these deposits than in contemporaneous Upper Cretaceous dinosaur-bearing units of western North America and Europe (Horner et al., 2004; Weishampel and Jainu, 2011; Dalla Vecchia, this volume), which are, in general, dominated by hadrosaurids. Only one new ornithopod taxon, Haya griva, has been identified from the Late Cretaceous of Mongolia in the last three decades (Makovicky et al., 2011).

In this chapter, we describe a new genus and species of hadrosauroid ornithopod, Plesiohadros djadokhtaensis, from the Alag Teeg locality, southern Gobi Desert, Mongolia. Plesiohadros is the second record of an ornithopod from the Djadokhta Formation (Barsbold and Perle, 1983), and the only named hadrosauroid taxon from Campanian-age rocks in Mongolia. In order to place Plesiohadros djadokhtaensis into its paleoecological and stratigraphic context within these Upper Cretaceous rocks of Mongolia, we outline the geological setting of the Djadokhta Formation at Alag Teeg and elsewhere in the Gobi Desert, review the different vertebrate assemblages of Djadokhta age, and assess the chronostratigraphy of the Djadokhta Formation. P. djadokhtaensis is then described, and its systematic relationships within Hadrosauroidea are assessed. Finally, we comment on the biostratrigraphy and biogeographic implications of this new form within the context of our updated hadrosauroid phylogeny.

Institutional Abbreviations MPC, Mongolian Paleontology Centre, Ulan Baatar, Mongolia; ROM, Royal Ontario Museum, Toronto, Ontario; MNHN GDF, Muséum national d’Histoire naturelle, Paris, France.