The mosasaurids (Mosasauridae) were a group of lizards that became highly specialized for marine life in the mid-Cretaceous. By the end of the Cretaceous, they had undergone an adaptive radiation, and showed a wide range of body sizes, locomotor styles, and diets. Their ranks included piscivores, apex predators, and durophages. Here, we report a new taxon, Xenodens calminechari gen. et sp. nov., from the upper Maastrichtian phosphates of Morocco, with dental specializations unlike those of any known reptile. Teeth form a unique dental battery in which short, laterally compressed and hooked teeth formed a saw-like blade. Unique features of tooth structure and implantation suggest affinities with the durophagous Carinodens. The tooth arrangement seen in Xenodens not only expands known disparity of mosasaurids, but is unique among Squamata, or even Tetrapoda. The specialized dentition implies a previously unknown feeding strategy, likely involving a cutting motion used to carve pieces out of large prey, or in scavenging. This novel dental specialization adds to the already considerable disparity and functional diversity of the late Maastrichtian mosasaurids and marine reptiles. This provides further evidence for a diverse marine fauna just prior to the K-Pg extinction.

mosasaurids（Mosasauridae）是一群蜥蜴，它们在白垩纪中期已高度专门化用于海洋生物。到白垩纪末期，它们经历了适应性辐射，并显示出各种各样的体型，运动方式和饮食。他们的行列包括食肉动物，先天性掠食者和硬壳动物。在这里，我们报告了一个新的分类单元，Xenodens Calminechari gen。等 十一月，来自摩洛哥的上马斯特里赫特磷酸盐，具有与任何已知爬行动物不同的牙齿专长。牙齿形成独特的牙科电池，其中短而侧向压缩且钩状的牙齿形成锯齿状的刀片。牙齿结构和植入的独特特征表明与食管硬齿Carinodens有亲和力。在Xenodens中看到的牙齿排列不仅扩大了已知蜥蜴的视差，而且在鳞am甚至四足纲动物中是独特的。专门的牙列意味着以前未知的进食策略，可能涉及用于从大猎物中雕刻出碎片或进行清除的切割运动。这种新颖的牙齿专长增加了晚期马斯特里赫特mosasaurids和海洋爬行动物已经相当大的差距和功能多样性。这为K-Pg灭绝之前的多种海洋动物提供了进一步的证据。