Please cite this article as: Owocki, K., Madzia, D., Predatory behaviour in mosasaurid squamates inferred from tooth microstructure and mineralogy, Cretaceous Research, https://doi.Dental morphology, microstructure and chemistry provide unique insights into various aspects 12 of the evolutionary history and ecology of extinct clades. However, most studies have focused 13 exclusively on the morphological aspects of teeth, while there are significantly fewer detailed 14 accounts of tooth

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... cture and mineralogy. Here we provide a full description of the 15 enamel and dentine microstructure of mosasaurid squamates based on an assessment of 16 isolated teeth belonging to two distantly related mosasaurid taxa, i.e., a russellosaurinan and a 17 mosasaurine, from the ?Coniacian-Santonian and Maastrichtian of Belgium. The obtained 18 data are further explored with regard to their value for inferences of mosasaurid predatory 19 behaviour. SEM observations have shown that the Schmelzmuster consists of columnar 20 enamel with an outer layer of parallel crystallites; transmitted light observations have further 21 revealed the presence of mantle dentine cushioning between enamel and orthodentine, and 22 electron microprobe analyses have demonstrated the unaltered enamel chemistry and 23 heterogeneous diagenetic alteration of dentine. Columnar enamel allows minute movements 24 without rupture under bending stress, and together with the presence of shock-absorbing 25 mantle dentine and possibly elevated Fe contents in the enamel, which increase its hardness 26 and enhance acid resistance, it is suggestive of a good ability of the teeth to withstand severe 27 mechanical damage. Such properties of teeth indicate adaptation to shaking and tearing large 28 and resisting prey.