The fossils of smaller plesiosaurs strongly suggests that Kronosaurus and its relatives may have preyed upon smaller plesiosaur species. This massive marine reptile was the biggest and baddest marine predator of the large inland sea that covered western Queensland in the Cretaceous. It used teeth the size of bananas to feast on ichthyosaurs, other plesiosaurs, turtles and fish. Kronosaurus has special air chambers on its snout that are used to scent prey in the same way as a pair of ears work, pinpointing exactly where a smell is coming from.
Body-length estimates had previously put the total length of Kronosaurus at 12.8 meters (43 feet). However, a recent study comparing fossil specimens of Kronosaurus to other pliosaurs suggests that the previous estimate was an exaggeration, with the true length probably being only 9–10 meters (30–33 feet). The teeth of Kronosaurus are large in length (exceeding 7 cm - the largest up to 30 cm long with 12 cm crowns). However, they lack carinae (cutting edges) and the distinct trihedral (three facets) of Pliosaurus and Liopleurodon teeth. The combination of large size, conical shape and lack of cutting edges allows for easy identification of Kronosaurus teeth in Cretaceous deposits from Australia. Kronosaurus lived in the Early Cretaceous Period (Aptian-Albian). The holotype specimen of the species K. queenslandicus was described by Longman in 1924, and is currently in the Queensland Museum. Hampe described a second species, K. boyacensis, in 1992 from Colombia. A preserved K. boyacensis can be seen in Villa de Leiva Boyaca, Columbia.