Fossils have been found from Victoria, Australia and date back 125-120 million years ago to Barremian-Aptian stages of the Early Cretaceous.

[2] In 1991, additional remains were reported including NMV-PI86040, an intercentrum (part of the vertebra) and NMV-PI86101, an isolated skull roof bone, likely representing either a frontal, a supratemporal or a parietal.

[4] It is known from four fragments of the lower jaw and several postcranial bones, including ribs, vertebrae, a fibula, and parts of the pectoral girdle.

[6] Koolasuchus was a large, aquatic temnospondyl, measuring up to 3 metres (9.8 ft) in length and weighing up to 500 kilograms (1,100 lb).

Although eusuchians and kin were common during the Early Cretaceous, they were absent from southern Australia 120 million years ago, possibly because of the cold climate.

By 110 Mya, represented by rocks in the Dinosaur Cove fossil locality, temperatures had warmed and crocodilians had returned to the area.