Abstract: Two new avian fossils from the Late Eocene of Xinjiang in western China appear to document the possible first occurrence of the extinct anseriform group Romainvilliinae (Anatidae) within China and Asia. The tarsometatarsus has several anseriform and anatid characters, and a combination of traits only reported from the romainvilliines among waterfowl. The absence of a medial flange on the second trochlea, its large size similar to extant swans, and asymmetrical proximal end of the plantar side of the third trochlea indicate that this specimen represents a new unnamed taxon. The equally large femur specimen exhibits morphology consistent with the anatid, and possible romainvilliine, Cygnopterus affinis from the Early Oligocene of Belgium. If these unnamed fossils represent Asian romainvilliines, they support a geographic range extension of the group, the occurrence of large body-sized romainvilliines in the Eocene, and an avifaunal biogeographic link between Europe and Asia during the Eocene prior to the end of the Turgai Strait as a dispersal barrier to most mammals.

摘要： 报道了发现于新疆晚始新世地层中的两件鸟类化石，这两件化石可能代表了雁形目一个绝灭亚科Romainvilliinae在中国乃至亚洲的首次发现。其中一件跗跖骨片段保存了多个雁形目鸭科鸟类的特征，同时保存了水禽中仅见于Romainvilliinae鸟类的特征组合。该跗跖骨属于一个个体很大的鸟类，与现生天鹅相当，其第二滑车内侧不存在突缘，第三滑车足底面的近中侧不对称，这些特征表明这件标本属于一个新属种。另一件股骨片段属于一个与跗跖骨标本个体同样大小的鸟类，其特征与在比利时发现的早渐新世可能属于鸭科Romainvilliinae的Cygnopterus affinis相一致。如果新发现的这两件标本确属亚洲的Romainvilliinae鸟类，则说明Romainvilliinae的地理分布范围也包括亚洲，大体型的Romainvilliinae鸟类在始新世时即已存在，并且也说明在阻断绝大多数哺乳动物扩散的图尔盖海峡干涸之前，欧亚之间的鸟类地理区系一直存在联系。