The nature and timing of biotic links between New Zealand and Antarctica in Mesozoic and early Cenozoic times

Abstract

Until the Early Cretaceous, when the first phases of rifting that preceded the eventual breakup of the Australasian sector of Gondwana occurred, New Zealand and Antarctica had a close geographic relationship on the eastern margin of Gondwana. After having been influenced by proximity to the Permian ice sheet, during which New Zealand and Antarctica shared elements of the Glossopteris flora, the eastern margin of Gondwana entered into a phase of predominantly cool-temperate climates that lasted throughout the Triassic. In the Jurassic, rotation of Gondwana had moved New Zealand and Antarctica into mid-latitudes and they experienced warm-temperate climates. These climatic conditions facilitated the dispersion of Tethyan marine faunas into the SW Pacific sector of eastern Gondwana. New Zealand and Antarctica shared many elements of the Tethyan marine faunas. Starting in Middle Jurassic times, earth movements of the Rangitata Orogeny began to create considerable areas of land in the New Zealand region. Eventually, by Late Jurassic and Early Cretaceous times, a large landmass had been developed, extending northwards towards New Caledonia, eastwards to the Chatham Islands, westwards to the Lord Howe Rise and southwards to the edge of the Campbell Plateau. Creation of this landmass, and its associated land and marine links, together with the equable warm-temperate conditions then apparent over large areas of Gondwana, provided favourable conditions for the dispersal of Gondwana elements into New Zealand. Ancestral stocks of at least some of New Zealand’s archaic endemic terrestrial biota may have dispersed from eastern Gondwana into New Zealand at this time. In the Early Cretaceous, land connections to eastern Gondwana became weakened by the onset of rifting along the future sites of the Tasman Sea and Southern Ocean. The eastern edge of Gondwana was rotated into high latitudes, and cool-temperate climates returned to New Zealand and Antarctica. Cool-temperate Austral marine faunas developed and were shared between New Zealand, Antarctica and southern South America. Land links between New Zealand and West Antarctica provided access for early angiosperms. However, all land links between New Zealand and Australia/Antarctica were broken after 85 Ma. From this time onwards the ancestral Tasman Sea and Southern Ocean became effective barriers to overland dispersal between eastern Gondwana and New Zealand. Subsequently, all terrestrial colonists had to arrive by either flying, swimming or floating. Many birds did so, but no terrestrial snakes and no mammals, except bats. Although land connections had been broken in the Late Cretaceous, shallow-water marine links continued to exist between New Zealand and West Antarctica until the late Paleocene (the Weddellian Province). However, as New Zealand moved progressively northwards and the Southern Ocean widened, such southern links gave way in latest Paleocene and early Eocene times to northern (Australian and Malayo-Pacific) links.

Early Cretaceous Biogeographic and Oceanographic Synthesis of Leg 123 (off Northwestern Australia)

“…Into the Early Cretaceous, "Palaeoaustral" elements gained importance, and Tethyan taxa declined markedly. Australia, New Zealand, Antarctica, and eastern India, all supported faunas having cool-temperature characteristics distinct from those of the Tethyan Realm (Stevens, 1980, fig. 4).…”

“…The equivalent Southern Hemisphere differentiation is mush less well documented and possibly less well developed (Crame, 1986). However, evidence is growing for a distinct Austral province for marine biota, at least for the interval from the Late Jurassic to the Late Cretaceous (e.g., Stevens, 1980;Stevens, 1989;Crame, 1986). Stevens (1980) reviewed the paleobiogeography of the southwest Pacific and described a major biogeographic shift that occurred at the end of the Jurassic.…”

“…However, evidence is growing for a distinct Austral province for marine biota, at least for the interval from the Late Jurassic to the Late Cretaceous (e.g., Stevens, 1980;Stevens, 1989;Crame, 1986). Stevens (1980) reviewed the paleobiogeography of the southwest Pacific and described a major biogeographic shift that occurred at the end of the Jurassic. In Middle to Late Jurassic time, the region was characterized by major influxes of Tethyan elements and an absence of Austral faunas.…”

The paleoaustral genusProtodoliumWilckens, 1922 (Mollusca: Gastropoda), and a new species from the Late Cretaceous of Chatham Islands, New Zealand

“…Protodolium was apparently restricted to the western sector of Gondwana including New Caledonia (A), New Zealand (B) and Chatham Islands (C). Base map from Stevens (1989). faunas of New Zealand. Approximately 150 species of bivalves, gastropods and scaphopods have been recorded from mainland New Zealand (J. D. S., unpublished data).…”

Skate-ing on thin ice: molecular ecology of longnose skates in the Southeast Pacific Ocean

“…The glaciation of Antarctica as consequence of the drastic cooling of ocean basins during the terminal Eocene event (Veevers, 2000), may be responsible of the radiation between Dipturus and Zearaja, approximately 36 Mya. The formation of the Southern Ocean from the warming influences from the rest of the world (Stevens, 1989), could result in connectivity bottlenecks on an ancestral Dipturus form of Gondwanic origin driving the speciation of Zearaja. Overall changes in deep ocean circulation during Eocene (Storey et al, 1988), may explain the distribution range of extant Zearaja species.…”