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| Xenodens calminechari scavenging a carcass of the elasmosaurid Zarafasaura oceanis. Longrich, Bardet, Schulp & Jalil, 2021. Artwork by Andrey Atuchin. twitter.com/AndreyAtuchin |
ABSTRACT
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.
Keywords: Mosasauridae, Squamata, Cretaceous, Maastrichtian, Africa
SQUAMATA Oppel (1811)
MOSASAURIDAE Gervais (1852)
MOSASAURINAE Gervais (1852)
Xenodens calminechari gen. et sp. nov.
Etymology. The genus name is derived from the Greek xenos, ‘strange’, and Latin dens, ‘tooth’. The species name derives from the Arabic calminechari (کالمنشار),‘like a saw’.
Holotype. MHNM.KH.333 (Figs. 3-5)
Horizon and locality. Upper Maastrichtian of Sidi Chennane phosphate mines, Khouribga Province, Morocco. Matrix and preservation are typical of Sidi Chennane, with a bleached white bone and pale, grey matrix characteristic of Couche III at Sidi Chennane (Fig. 3). The matrix is coarse, with a small fraction of fine particles, and contains teleost fragments. This coarse matrix is typical of fossils from upper Couche III at Sidi Chennane.
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| Figure 9. Reconstruction of Xenodens calminechari scavenging a carcass of the elasmosaurid Zarafasaura oceanis. Artwork by Andrey Atuchin. |
Nicholas R. Longrich, Nathalie Bardet, Anne S. Schulp and Nour-Eddine Jalil. 2021. Xenodens calminechari gen. et sp. nov., A Bizarre Mosasaurid (Mosasauridae, Squamata) with shark-like cutting teeth from the upper Maastrichtian of Morocco, North Africa. Cretaceous Research. In Press, 104764. DOI: 10.1016/j.cretres.2021.104764
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