Kronosaurus

Kronosaurus (/ˌkrɒnoʊˈsɔːrəs/ KRON-oh-SOR-əs; meaning "lizard of Kronos") is an extinct genus of short-necked pliosaurs that lived during the Early Cretaceous period (Aptian to Late Albian) in what is now Australia. It is a monotypic genus with one species K. queenslandicus, described in 1924 from the Toolebuc Formation in Queensland, Australia. With traditionally attributed fossils indicating a total length of up to 10 meters (33 ft), Kronosaurus may have been among the largest pliosaurs.

The status of this genus is contentious due to the fragmentary nature of the holotype, which is a non-diagnostic partial mandibular symphysis. This led to a 2021 study to reduce Kronosaurus to a dubious taxon and reassign all other fossils previously assigned to it, including several partial skeletons, to a new genus. The move was heavily criticized as introducing taxonomic instability by supplanting an iconic name when a preferred solution would have been to petition the ICZN to designate a diagnostic neotype. Although a petition has yet to be submitted, several specimens have already been proposed as neotypes, and subsequent studies have maintained the use of Kronosaurus on this account.

Kronosaurus inhabited the Eromanga Sea, an inland sea that covered parts of central and eastern Australia during the Early Cretaceous and reached rather cold temperatures. It was probably an apex predator that preyed on other marine reptiles. Remains of plesiosaurs and turtles have been found as stomach contents of traditional specimens from the Toolebuc Formation.