ABSTRACT

Recent palaeontological research in submerged caves of the north-eastern Yucatán Peninsula (YP) in Mexico has resulted in the identification of a diverse megafaunal assemblage in the area, among them Late Pleistocene ground sloths assigned to the family Megalonychidae (Xenarthra). Here we report on a new species of Megalonychidae, Xibalbaonyx exinferis n. sp., from a new fossil locality named cenote Tortugas, located west of Puerto Morelos in the federal state of Quintana Roo. The taxon is based on a fragmentary left mandibular ramus, an atlas, and a left humerus. The new taxon is diagnosed by the presence of two mental foramina on the short symphyseal spout, a caniniform being the smallest mandibular tooth, and the anterolaterally directed aperture of the mandibular foramen on the lateral surface of the mandible. Xibalbaonyx exinferis is the third endemic megalonychid documented for the north-eastern Yucatán Peninsula and thus provides increasing evidence for an ecological isolation of the area from the rest of Mexico during the Pleistocene.

摘要

最近对墨西哥尤卡坦半岛 (YP) 东北部水下洞穴的古生物学研究已确定该地区存在多种巨型动物群落，其中包括属于巨爪科 (Xenarthra) 的晚更新世地懒。在这里，我们报告了巨爪科的一个新物种Xibalbaonyx exinferisn. sp.，来自一个名为 cenote Tortugas 的新化石产地，位于联邦金塔纳罗奥州的莫雷洛斯港以西。该分类群基于残缺的左下颌支、图谱和左肱骨。新分类群的诊断依据是在短交汇口上存在两个颏孔，犬齿是最小的下颌牙，下颌骨外侧面有下颌孔的前外侧孔。Xibalbaonyx exinferis是尤卡坦半岛东北部记录的第三种地方性巨爪动物，因此为更新世期间该地区与墨西哥其他地区的生态隔离提供了越来越多的证据。