Wherever bony fish are abundant there will be fishing animals, including, on occasion, non-avian dinosaurs. In fact, fishing non-avian dinosaurs, such as Baryonyx, existed in Early Cretaceous times. The rivers of the Australia, however, have a unique group of fish-catching theropods called the pouches. These generally belong to the same genus, Saccosaurus, and have evolved from Kakuru, the same ancestor as the cribrum. They are quite amphibious, being happier sculling about on the surface of the water and diving to the river bed than waddling about on land. Their buoyant bodies, big heads and webbed feet make the adults look very ungainly and vulnerable as they tend to their nests on riverbanks. The nests are built of mud and sticks, above the local flood level. The eggs, hatchlings and juveniles resemble those of a totally land-living creature, suggesting that it has not been long since the pouch evolved from a terrestrial ancestor. The swimming habits of the young pouches must be learned at their parents' side while their bodies develop the aquatic adaptations of adulthood.
In the water, the adult pouch swims gracefully on the surface, with its striped tail waving as a flag. It moves steadily with powerful strokes of its webbed hind feet and dives swiftly after fish, steering with a membrane between the forelimb and the body. The catch is held in a bag of skin beneath the lower jaw until the pouch returns to land.