The rare cricetid rodent Bibimys Massoia, 1980 contains three extant species that are distributed in the lowlands of eastern South America between 35°S and 20°S and distinguished mostly by subtle morphological and genetic features. Several fragmented jaws belonging to this genus were recovered from Late Quaternary deposits located in northeastern Brazil, forming part of a rich archaeological and paleontological small mammal assemblage that has been recovered from caves in the Serra da Capivara, state of Piauí. This material is described herein as belonging to a new species, the most hypsodont member of the genus. The specimens also represent an extralimital occurrence of this sigmodontine, as the nearest extant population of Bibimys is ∼1,200 km to the south. Because there are few reliable records of extinct small mammals from the Pleistocene–Holocene transition on the South American continent, in describing this new sigmodontine we extend the records of past biodiversity preserved in the Quaternary deposits of tropical South America. This new species likewise highlights that the Serra da Capivara deposits are promising for understanding the evolutionary history of cricetid rodents.

中文翻译：

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来自巴西东北部的一种新化石仓鼠（啮齿目，Sigmodontinae），对热带第四纪小型哺乳动物灭绝的评论

稀有的啮齿动物 Bibimys Massoia，1980 年包含三个现存物种，它们分布在南美洲东部 35°S 和 20°S 之间的低地，主要以细微的形态和遗传特征区分。从位于巴西东北部的晚第四纪沉积物中发现了属于该属的几个破碎的颌骨，构成了丰富的考古和古生物小型哺乳动物组合的一部分，该组合是从皮奥伊州塞拉达卡皮瓦拉的洞穴中发现的。这种材料在本文中被描述为属于一个新物种，该属中最有棱角的成员。这些标本也代表了这种 sigmodontine 的一个额外的出现，因为最近的 Bibimys 种群距离南部约 1,200 公里。由于南美洲大陆更新世-全新世过渡时期灭绝的小型哺乳动物的可靠记录很少，因此在描述这种新的西格莫唐动物时，我们扩展了保存在南美洲热带第四纪沉积物中的过去生物多样性记录。这个新物种同样强调了 Serra da Capivara 矿床有望帮助了解蝾螈啮齿动物的进化历史。