Abstract:
Fossil Crocodylia are taxonomically diverse in South America, particularly in the upper Miocene Urumaco Formation (Venezuela). Among them is the giant alligatoroid Purussaurus, previously known from the upper Miocene Solimoes Formation in Brasil (P. brasiliensis) and the middle Miocene of La Venta in Colombia (P. neivensis). New specimens of Crocodylia from the Urumaco Formation are described and a new species, Purussaurus mirandai, erected. This is characterised by a large, elongate and extremely flat skull, a very large narial opening comprising almost 60% of rostral length and a large incisive foramen that extends anteriorly between the fossae for the first mandibulary teeth. Purussaurus mirandai sp. nov. was the largest predator in the swampy environments and represented the top trophic level in the Urumaco assemblage. A phylogenetic analysis of 164 characters in 68 ingroup crocodile taxa supported the association of P. neivensis and P. mirandai with five synapomorphies and confirmed the sister-group relationship of the genus with the Nettosuchidae.
