New cranial and postcranial elements of Mourasuchus (Alligatoroidea: Caimaninae) from the late Miocene of Venezuela and their palaeobiological implications

Abstract

ABSTRACT A partial skeleton of Mourasuchus, one of the most peculiar crocodylians of all time, that includes cranial and postcranial elements recovered from the late Miocene bone-beds of the Urumaco Formation (northwestern Venezuela) is herein described. Based on the presence of tall squamosal eminences, we assigned it to Mourasuchus arendsi. To provide an empirical assessment of the palaeobiological affinities of Mourasuchus, we performed estimations of the body mass and body length based on several Mourasuchus skull measurements, and an analysis of death roll capability. Our results indicate that Mourasuchus was indeed a large crocodylian, with a body length bigger than 9 m and weighed more than 4 tons. We find that Mourasuchus arendsi was incapable of executing the ‘death roll’ as a feeding behaviour and as such was unable to predate giant mammals, which are relatively common in the Urumaco Formation. Finally, the specimen includes a slender humerus, which may indicate that Mourasuchus had weak forelimbs and would spend more time in the water.