Evolution of upper cretaceous phytogeoprovinces and their pollen flora

Abstract

Two major phytogeoprovinces can be recognized during the Albian. The presence of elater-bearing palynomorphs distinguishes the phytogeoprovinces of northern South America, north Africa and the Middle East. South America and Africa were separated completely in the late Albian by the opening of the South Atlantic. Several late Albian marine transgressions and regressions created new land areas isolated by epeiric seas or oceans. The biotas which characterized these territories evolved independently. Normapolles pollen appeared in eastern Europe during the early Cenomanian. Their eastward migration was halted by a transgressive Turonian sea extending from north to south between Europe and Asia. Their westward migration was restricted by a North American epeiric sea which penetrated North America as a narrow arm through the western interior, joining the boreal Arctic sea and southern Gulf of Mexico. A Turonian—early Maastrichtian Aquilapollenites flora evolved and flourished exclusively in Siberia, the Far East, northeastern China, and western North America. In the South American—north African phytogeoprovince, elater-bearing palynomorphs were gradualy replaced by a unique Senonian Constantinisporis flora. India was included in this province during the Senonian. A Nothofagidites flora was initiated in the Coniacian, separating an Austral phytogeoprovince of southern South America, south Africa, Australia, New Zealand and Antarctica. Late Maastrichtian sea withdrawal led to the connection of the phytogeoprovinces and allowed an interprovincial mixing of the flora. During the latest Maastrichtian, Aquilapollenites reached eastern North America, northern South America, north Africa, western Scotland, India, and China. Likewise, Normapolles reached western North America, north Africa, India and China. However, a cooling trend in the latest Cretaceous climate destroyed most of the flora, particularly the Aquilapollenites and Constantnisporis floras. Normapolles survived until the Oligocene. The Austral phytogeoprovince remained separates and preserved its characteristics proteaceous and Nothofagus flora up to present time.