Cooyoo is a primitive ichthyodectid found in Lower Cretaceous strata of Queensland, Australia. As with all other ichthyodectids, it was a predator of smaller fish. It is known from complete specimen with length about . The type species, named in 1987, is C. australis, although Arthur Smith Woodward originally named it as a species of Portheus (now a probable synonym of Xiphactinus) in 1894, which was later amended to Xiphactinus. References Ichthyodectidae Prehistoric fish of Australia Fossil taxa described in 1987