Endemism and heterochroneity in the Late Cretaceous (Campanian) to Paleocene palynofloras of Seymour Island, Antarctica: implications for origins, dispersal and palaeoclimates of southern floras

Abstract

Abstract Late Cretaceous (Campanian) to Paleocene nearshore marine-coastal/deltaic sediments (López de Bertodano and Sobral Formations) from Seymour Island, Antarctica, contain abundant marine and terrestrial palynomorphs. Marine dinoflagellate cysts, and spores and pollen of land plants from 510 samples exhibit varying levels of provincialism: (1) Seymour Island-James Ross Island basin endemic species; (2) Antarctic endemic species; (3) Weddellian Province (southern South America-Western Antarctica-New Zealand-southeastern Australia) species; (4) Austral species; and (5) Cosmopolitan species. A significant proportion of the Antarctic Cretaceous-Tertiary terrestrial vegetation evolved in southern polar latitudes. Almost half of the late Maastrichtian angiosperm pollen flora is apparently endemic to the Seymour Island-James Ross Island basin or Antarctica. The late Campanian-Maastrichtian dinoflagellate cyst assemblages also include a significant Antarctic or Weddellian provincial component. Climatic conditions in the Late Cretaceous were moist and equable. Many species that evolved in these polar latitudes became isolated due to various geographical, climatic or biological barriers. Other species dispersed northward, presumably following routes of similar climate. Some Seymour Island latest Cretaceous angiosperm species which subsequently appeared in the Paleocene or Eocene in New Zealand and southeastern Australia, have modern relatives living in mid- to low latitudes.