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Dakosaurus (Thalattosuchia) bite sliced big prey into chunks



From: Ben Creisler
bcreisler@gmail.com

A new online paper in the Anatomical Record:

Young, M. T., Brusatte, S. L., Beatty, B. L., De Andrade, M. B. and
Desojo, J. B. (2012)
Tooth-On-Tooth Interlocking Occlusion Suggests Macrophagy in the
Mesozoic Marine Crocodylomorph Dakosaurus.
Anatomical Record (advance online publication)
doi: 10.1002/ar.22491
http://onlinelibrary.wiley.com/doi/10.1002/ar.22491/abstract


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.