New Data on Ergilornithids (Aves: Ergilornithidae) from Central Asia

Abstract This paper describes materials of ergilornithids (Aves: Ergilornithidae) from the Middle Miocene Sharga locality in Mongolia. A new species, Urmiornis shargensis sp. nov., and another unnamed representative of the genus Urmiornis, similar to U. orientalis, have been identified based on distal tibiotarsi. The co-occurrence of two ergilornithid taxa in Neogene faunas is reported for the first time. Urmiornis shargensis resembles morphologically both the Pliocene U. dzabghanensis and Late Eocene Proergilornis minor. In addition, a cervical vertebra of an indeterminate ergilornithid, partially similar to the vertebrae of Struthionidae, is described from Sharga. The taxonomic affiliation of ergilornithid tibiotarsi from the Upper Eocene Ergilin-Dzo Formation in Mongolia is discussed: one specimen from the Bayan-Tsav locality is assigned to Proergilornis minor, whereas tibiotarsi of Ergilornis rapidus remain unknown. The morphology of Sinoergilornis guangheensis from the Upper Miocene of China is discussed and compared with other Neogene ergilornithid species. As a result of the revision, S. guangheensis is transferred to the genus Urmiornis.