The Old World fossil record of the family Camelidae is patchy, but a new partial cranium and some other remains of Camelus grattardi from the Mille-Logya Project area in the Afar, Ethiopia, greatly increase the fossil record of the genus in Africa. These new data – together with analysis of unpublished and recently published material from other sites, and reappraisal of poorly known taxa – allow for a comprehensive phylogenetic analysis showing that C. grattardi is the earliest (2.2–2.9 Ma) and most basal species of the genus. We also show that the lineages leading to the extant taxa C. dromedarius and C. bactrianus diverged much higher in the tree, suggesting a recent age for this divergence. A late divergence date between the extant species is consistent with the absence of any fossil forms that could be ancestral, or closely related, to any of the extant forms before the late Pleistocene, but stands in contrast to molecular estimates which place the divergence between the dromedary and the Bactrian camel between 8 and 4 million years ago.

中文翻译：

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Camelus grattardi（哺乳动物，骆驼科）的新遗骸来自埃塞俄比亚的上新世 - 更新世和该属的系统发育

骆驼科的旧世界化石记录不完整，但来自埃塞俄比亚阿法尔 Mille-Logya 项目地区的骆驼科动物新的部分头盖骨和其他一些遗骸大大增加了该属在非洲的化石记录。这些新数据——连同对来自其他地点的未发表和最近发表的材料的分析，以及对鲜为人知的分类群的重新评估——允许进行全面的系统发育分析，表明 C. grattardi 是最早（2.2-2.9 Ma）和最基础的物种属。我们还表明，导致现存分类群 C. dromedarius 和 C. bactrianus 的谱系在树中分叉得更高，表明这种分叉的年龄最近。现存物种之间的晚期分化日期与没有任何可能是祖先或密切相关的化石形式一致，