title: Tooth serration morphologies in the genus Machimosaurus (Crocodylomorpha, Thalattosuchia) from the Late Jurassic of Europe.
abstract: Machimosaurus was a large-bodied durophagous/chelonivorous genus of teleosaurid crocodylomorph that lived in shallow marine and brackish ecosystems during the Late Jurassic. Among teleosaurids, Machimosaurus and its sister taxon 'Steneosaurus' obtusidens are characterized by having foreshortened rostra, proportionally enlarged supratemporal fenestrae and blunt teeth with numerous apicobasal ridges and a shorter anastomosed ridged pattern in the apical region. A recent study on 'S.' obtusidens dentition found both true denticles and false serrations (enamel ridges which contact the carinae). Here, we comprehensively describe and figure the dentition of Machimosaurus, and find that Machimosaurus buffetauti and Machimosaurus hugii have four types of serration or serration-like structures, including both denticles and false denticles on the carinae. The denticles are irregularly shaped and are not always discrete units, whereas the false denticles caused by the interaction between the superficial enamel ridges and the carinae are restricted to the apical region. Peculiarly, the most 'denticle-like' structures are discrete, bulbous units on the apicobasal and apical anastomosed ridges of M. hugii. These 'pseudo-denticles' have never, to our knowledge, previously been reported among crocodylomorphs, and their precise function is unclear. They may have increased the surface area of the apical region and/or strengthened the enamel, both of which would have been advantageous for a durophagous taxon feeding on hard objects such as turtles.
authors.affiliation: School of GeoSciences, Grant Institute, University of Edinburgh , The King's Buildings, Edinburgh EH9 3FE, UK ; School of Ocean and Earth Science, National Oceanography Centre , University of Southampton , Southampton SO14 3ZH, UK.
authors.forename: Mark T
authors.initials: MT
authors.lastname: Young
authors.affiliation: Department of Earth Sciences, Natural History Museum, London SW7 5BD, UK.
authors.forename: Lorna
authors.initials: L
authors.lastname: Steel
authors.affiliation: School of GeoSciences, Grant Institute, University of Edinburgh , The King's Buildings, Edinburgh EH9 3FE, UK ; National Museums Scotland, Chambers Street, Edinburgh EH1 1JF, UK.
authors.forename: Stephen L
authors.initials: SL
authors.lastname: Brusatte
authors.affiliation: School of GeoSciences, Grant Institute, University of Edinburgh , The King's Buildings, Edinburgh EH9 3FE, UK.
authors.forename: Davide
authors.initials: D
authors.lastname: Foffa
authors.affiliation: Sciences et Géologie Normandes, 76620 Le Havre, France.
authors.forename: Yves
authors.initials: Y
authors.lastname: Lepage
keywords: Europe; Machimosaurus; Teleosauridae; dental morphology; enamel ridges; ‘pseudo-denticles’