Data from: First record of Toxodontidae (Mammalia, Notoungulata) from the late Miocene–early Pliocene of the southern central Andes, NW Argentina

A new species of toxodontid notoungulate, Xotodon maimarensis n. sp., is described from the Maimará Formation (late Miocene–early Pliocene), Jujuy Province, northwestern Argentina. This is the first record of a toxodontid from the Eastern Cordillera. The specimen is housed at the Museo de Geología, Mineralogía y Paleontología, Instituto de Geología y Minería de la Universidad Nacional de Jujuy. It consists of an incomplete mandible preserving the right mandibular ramus with part of the dental series, partially preserved symphysis with all the incisors, and a small portion of the left ramus without teeth. The following characters distinguish it as a new taxon: symphysis long and narrow with slight divergence of its lateral borders; strong procumbence of lower incisors and deeply implanted i3; chin angle lower than in X. major and X. cristatus and bulging labial keel limiting strong lateral concavities. Comparative analysis in the context of the recently revised Neogene Toxodontidae indicates that the Maimará specimen shares mandibular features and dental characters with Xotodon and Mixotoxodon, differing from the latter by the more upraised symphysis. The phylogenetic position of Xotodon maimarensis n. sp. supports the taxonomic interpretation of the studied specimen as a new species of Xotodon. This new Toxodontidae increases the knowledge of the diversity and radiation of this group of notoungulates in northwest Argentina.

本文记述了产自阿根廷西北部胡胡伊省（Jujuy Province）迈马腊组（Maimará Formation，晚中新世-早上新世）的一种新的箭齿兽科（Toxodontidae）南方有蹄目（Notoungulate）物种：Xotodon maimarensis新种。这是东科迪勒拉（Eastern Cordillera）地区首次记录到箭齿兽科物种。该标本馆藏于胡胡伊国立大学地质与矿业研究所地质、矿物与古生物学博物馆（Museo de Geología, Mineralogía y Paleontología, Instituto de Geología y Minería de la Universidad Nacional de Jujuy）。标本包含一件不完整的下颌骨：保存有部分齿列的右下颌支、保留全部门齿且部分保存的联合部，以及一段无齿的左下颌支小段。该新类群具有以下鉴别特征：联合部长而窄，侧缘轻微外展；下门齿强烈前伸，i3深植于颌骨内；下颌角小于Xotodon属（Xotodon）的X. major与X. cristatus，且凸起的唇侧龙骨界定了明显的侧凹。基于近期修订的新近纪箭齿兽科类群开展的比较分析显示，迈马腊标本与Xotodon属及Mixotoxodon属（Mixotoxodon）共享下颌骨及牙齿特征，但其联合部位置更高，这一点与后者存在差异。Xotodon maimarensis新种的系统发育位置支持将本次研究的标本归为Xotodon属新种的分类学判断。这一新发现的箭齿兽科物种，丰富了我们对阿根廷西北部该类南方有蹄类类群的多样性与辐射演化的认知。