河北磁县九龙口中中新世“Macrotherium cf.M.brevirostris”的分类地位

The taxonomic status of “Macrotherium cf. M. brevirostris” from the Middle Miocene of Jiulongkou, Cixian County, Hebei Province

河北磁县九龙口是我国东部地区一个比较重要的中中新世化石地点,该地点出土的爪兽化石的分类地位一直未能确定。近年来的系统发育分析和通古尔地区新材料的研究显示,九龙口的爪兽应当是Chalicotherium属内一个未定名的新种,本文将之命名为C.hebeiense sp.now.。该种以下颌粗壮、下颌联合的后缘在p4-m1之间、下颌支深、前臼齿列短、P3中谷封闭、p4下内尖发育且孤立、下臼齿的下三角座U型及下后附尖弱等特征为鉴定依据。柴达木盆地曾经发现过的一段下颌残段(IVPPV 12531)也可暂时归入此种。

Materials of chalicothere from Jiulongkou, Cixian County, Hebei Province were identified as Macrotherium cf. M. brevirostris by Hu （1959） and Macrotherium sp. by Chen and Wu （1976）. However, Macrotherium was Nomen nudum and erected as Chalicotherium by Anquetin et al. （2007）. Recent phylogenetic analysis （Chen et al., 2012） and new discoveries from Tunggur （Liu and Zhang, 2012） showed that the Cixian materials were markedly distinct from Chalicotherium brevirostris. Further observation and comparison suggest that the Cixian materials should represent a new species.