Benjamin P Kear

Academic paper

Cretaceous Research

24

277-303

Marine reptile fossils are common in the Cretaceous epicontinental and continental-margin marine deposits of Australia but much of the material is sparsely documented. A review of current localities indicates that the majority of remains are known from the Aptian�Albian epicontinental marine units of the Eromanga Basin in Queensland, New South Wales and South Australia. Fragmentary specimens have also been recovered from Berriasian, Hauterivian�Barremian, Albian�Cenomanian, Cenomanian� Turonian and Maastrichtian marine deposits of Western Australia, Aptian or Albian continental margin rocks of the Northern Territory and Aptian�Albian freshwater sediments of New South Wales and Victoria. Interestingly, many of these deposits represent Cretaceous high latitude-polar environments and some include palaeoclimatic indicators suggesting very cold to near freezing conditions. As currently known, the Australian Cretaceous marine reptile fauna comprises one family of ichthyosaurs (Ophthalmosauridae), as many as five families of plesiosaur (Rhomaleosauridae, Pliosauridae, Polycotylidae, Elasmosauridae and possibly Cryptoclididae or Cimoliasauridae sensu Acta Zool. Fenn. 213 (2001)), one family of chelonioid sea turtle (Protostegidae) and indeterminate mosasaurids. Although few named Australian species may be regarded as valid, the stratigraphic distribution of taxa correlates well with that from elsewhere. Plesiosaurs and ichthyosaurs dominate Lower Cretaceous deposits with plesiosaurs showing a high taxonomic diversity (including the earliest known polycotylids), particularly in the Aptian. Albian faunas see the advent of chelonioid turtles with a corresponding reduction in plesiosaur diversity (through the loss of rhomaleosaurids) and a marked increase in the numbers of ichthyosaur remains. Upper Cretaceous units have produced only fragmentary specimens of primarily plesiosaurs and mosasaurs with ichthyosaurs limited to rocks of Cenomanian age.

Marine reptiles; Cretaceous; Australia; Current deposits; Taxonomy; Distribution

English