Tooth‐On‐Tooth Interlocking Occlusion Suggests Macrophagy in the Mesozoic Marine Crocodylomorph
Metriorhynchidae was a peculiar but long‐lived group of marine Mesozoic crocodylomorphs adapted to a pelagic lifestyle. Recent discoveries show that metriorhynchids evolved a wide range of craniodental morphotypes and inferred feeding strategies. One genus, Dakosaurus, is arguably the most aberrant marine crocodylomorph due to its large, robust, ziphodont teeth; very low tooth count; and brevirostrine/oreinirostral snout. We here report an additional unusual feature of Dakosaurus that is unique among marine crocodylomorphs: tightly fitting tooth‐to‐tooth occlusion, whose inference is supported by reception pits along the upper and lower tooth rows, indicative of vertically orientated crowns that were in close contact during occlusion, and three distinct types of dental wear. These include irregular spalled surfaces near the apex (probably caused by tooth‐food contact), semi‐circular wear near the base, and elongate surfaces extending along the mesial and distal margins of the teeth, obliterating the carinae (including the denticles). Scanning electron micrographs show that these latter surfaces are marked by parallel apicobasal striations, which in extant mammals reflect tooth–tooth contact. As such, we interpret the carinal wear facets in Dakosaurus as being formed by repeated tooth–tooth contact between the mesial and distal margins of the teeth of the upper and lower jaw. We posit that this increased the available shearing surface on their high crowns. Together, these wear patterns suggest that occlusion in Dakosaurus was specialized for cutting large and abrasive prey items into portions small enough to swallow, making it a prime example of an aquatic reptile with macrophagous feeding habits. Anat Rec, 2012. © 2012 Wiley‐Periodicals, Inc.
Document Type: Research Article
Affiliations: 1: Department of Anatomy, New York College of Osteopathic Medicine, Northern Boulevard, Old Westbury, New York, New York 2: Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul – UFRGS, Av. Bento Gonçalves 9500, Porto Alegre (RS), Brazil 91501-970, C.P. 15001 3: Sección Paleontología de Vertebrados, Museo Argentino de Ciencias Naturales ‘Bernardino Rivadavia,’ Angel Gallardo 470, C1405DRJ, Buenos Aires, Argentina
Publication date: July 1, 2012