Long, long after Deinosuchus ruled Late Cretaceous North America, and longer still after Sarcosuchus ruled Early Cretaceous Africa and South America, Purussaurus brasiliensis began its reign. Purussaurus was a giant caiman from Miocene (Early Neogene) South America. Oddly enough, so far only skulls have been found, and its body length has been estimated at anywhere from 7.6–9.2 metres (25–30 ft) to 9.9–15.8 metres (32–52 ft)! However, its skull itself is smaller than Deinosuchus’, so these estimates take into account the longer body length of caimans. Either way, Purussaurus was the largest crocodilian of its time, and would have preyed on large Miocene mammals, using the death roll like modern crocodilians to subdue its prey. Its large size may have eventually been its downfall, as it was harder for it to adapt to a changing environment, while the smaller caimans lived on.

Purussaurus brasiliensis has been found in the the Solimões Formation, the Castilletes Formation, the Culebra Formation, and the Socorro Formation. It would have preyed on a wide variety of Miocene animals across South America, including astrapotheriids like Hilarcotherium, protoceratids like Paratoceras, metatherians like Lycopsis, giant ground sloths, monkeys like Panamacebus and Solimoea, dugongs like Culebratherium, anhingas, and other caimans like Culebrasuchus.