Abstract The Mexican record of notoungulates is scarce. So far, the only described species in Mexico is represented by Mixotoxodon larensis, which has limited in Michoacan and Veracruz. This work describes the MG-ITCM-405P toxodont material discovered in Tampico (late Pleistocene) that confirms the presence of the Mixotoxodon larensis in Tamaulipas (northeastern Mexico). The specimen consists of an almost complete jaw, which stands out for having the premolars (p2, p3 and p4) and molars (m1, m2 and m3) rights in good condition, being perhaps the best preserved toxodonts material in the country. Statistical analyzes of sexual dimorphism (metric and morphological) of the Mixotoxodon larensis showed that the metric variations in molars are related to a difference in size between males and females, with m1 being the most dimorphic. The variations of the lingual folds of the molars also follow a similar pattern, but there is a strong influence of other variables such as age, diet and to a lesser extent, biogeographical variations.

中文翻译：

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墨西哥塔毛利帕斯州晚更新世的毒齿兽遗骸。Mixotoxodon larensis 发生的确认 (Van Frank, 1957) 和性别二态性分析

摘要 墨西哥的无蹄类动物记录很少。到目前为止，墨西哥唯一描述的物种是 Mixotoxodon larensis，它在米却肯州和韦拉克鲁斯州有限。这项工作描述了在坦皮科（更新世晚期）发现的 MG-ITCM-405P 毒齿动物材料，该材料证实了在塔毛利帕斯州（墨西哥东北部）存在 Mixotoxodon larensis。该标本由一个几乎完整的颌骨组成，其突出之处在于前磨牙（p2、p3 和 p4）和臼齿（m1、m2 和 m3）的状况良好，这可能是该国保存最完好的齿科动物材料。Mixotoxodon larensis 的性别二态性（度量和形态）的统计分析表明，臼齿的度量变化与雄性和雌性之间的大小差异有关，其中 m1 是二态性最强的。