Guarinisuchus munizi was a recently described (March 2008) dyrosaurid from the Paleocene Maria Farinha Formation deposits of North-eastern Brazil. The Dyrosaurids were a group of long-snouted marine crocodylomorphs that appeared during the Cretaceous and survived the K-T extinction, and known for rather fragmentary materials from South and North America and Africa. Dyrosaurids are thought to have briefly occupied the niche let vacant by the disappearance of the mesozoic metriorhynchids and mosasaurs. Guarinisuchus is to date the most complete representative of the south american dyrosaurids. Its size is small (3 meters) compared to the other members of the group.