A pug-nosed crocodyliform from the Late Cretaceous of Madagascar.

Abstract

Although the image of crocodyliforms as 'unchanged living fossils' is naive, several morphological features of the group are thought to have varied only within narrow limits during the course of evolution. These include an elongate snout with an array of conical teeth, a dorsoventrally flattened skull and a posteriorly positioned jaw articulation, which provides a powerful bite force. Here we report an exquisitely preserved specimen of a new taxon from the Late Cretaceous of Madagascar that deviates profoundly from this Bauplan, possessing an extremely blunt snout, a tall, rounded skull, an anteriorly shifted jaw joint and clove-shaped, multicusped teeth reminiscent of those of some ornithischian dinosaurs. This last feature implies that the diet of the new taxon may have been predominantly if not exclusively herbivorous. A close relationship with notosuchid crocodyliforms, particularly Uruguaysuchus (Late Cretaceous, Uruguay) is suggested by several shared derived features; this supports a biogeographical hypothesis that Madagascar and South America were linked during the Late Cretaceous.