Southern Australian endemic and semi-endemic foraminifera: a preliminary report

Abstract

Abstract. The Cenozoic in southern Australia contains many foraminifera endemic to the region in neritic (intermediate- to shallow-water) facies. They were mostly epifaunal and inhabited waters to some 300 m deep. This endemism is first obvious in the later Eocene when Maslinella, Crespinina and Wadella, among others, evolved. More than half of the Eocene endemic species disappeared in the Eocene or Oligocene. There followed in the Oligocene the evolution of such species as Parrellina imperatrix and Astrononion centroplax. The Miocene was a time of slightly reduced endemism and is characterized by migration into the region of many larger (sub)tropical taxa such as Lepidocyclina and Cycloclypeus. The long-ranging genus Notorotalia emerged about 50 Ma ago and is still common in modern southern mid-latitude waters. The youngest common extant species which made their first appearance in the Pliocene–Quaternary include Discorbis dimidiatus and Parredicta porifera, both with a test up to 1.5 mm in diameter. A similar pattern has been recorded in New Zealand.Four phases of endemism can be recognized: later Eocene, Oligocene, Miocene and Pliocene–Quaternary. It appears that the four phases were all stimulated in response to major marine transgressions, respectively the Wilson Bluff ( = Khirthar), Aldingan, Clifton–Longfordian and Hallet Cove–Glanville transgressions. Probably they signal four important stages in the transformation of water masses along the southern continental margin.