The Oligocene fossil deposits from Valley of Lakes in Central Mongolia have provided a wealth of rodent fossils. Among these, cricetids are a very important part. To date, only the Miocene genera have been described in detail. Here, we focus on the Oligocene genus Eucricetodon from this region. Eucricetodontinae are the most abundant fossils in the Oligocene Valley of Lakes faunas. The present study consists of the description of five species of cricetid rodents from 43 localities ranging in age from the early Oligocene to the early-late Oligocene. In addition to Eucricetodon asiaticus described in Mongolia in 1923, we have found Eucricetodon bagus and Eucricetodon jilantaiensis that were described from Nei Mongol and Eucricetodon occidentalis discovered in Kazakhstan. This taxonomical study provides new information regarding the evolution of the Cricetidae in Central and Eastern Asia during the Oligocene and, more particularly, regarding their phylogenetic relationships and the evolutionary trends.

中文翻译：

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Eucricetodon属（Rodentia，Mammalia）从湖谷（蒙古）的进化：分类学描述和地层分布的更新。

来自蒙古中部湖谷的渐新世化石沉积物提供了大量的啮齿动物化石。其中，creecitids是非常重要的部分。迄今为止，仅详细描述了中新世属。在这里，我们集中于该地区的渐新世属Eucricetodon。Eucricetodontinae是渐新世湖泊动物群中最丰富的化石。本研究包括从早期渐新世到晚渐新世的43个地区的5种of骨啮齿动物的描述。除了1923年在蒙古描述的Eucricetodon asiaticus外，我们还发现了Nei Mongol和Neucricetodon bagus和Eicricetodon jilantaiensis。Eucricetodon occidentalis在哈萨克斯坦发现。这项分类研究为渐新世期间中亚和东亚象甲科的进化提供了新的信息，尤其是它们的系统发生关系和进化趋势。