Cretaceous angiosperm pollen of the Atlantic coastal plain and its evolutionary significance

ARBORETUM [voL. 50 detailed documentation of both the stratigraphic and systematic aspects is in progress and will be presented later in more complete form, but the general results seem clear enough to be summarized in this preliminary paper.In general, morphological terminology follows Erdtman (1952), though some terms of Pflug (1953) are used in discussing triporate pollen. GEOLOGICAL BACKGROUNDThe Cretaceous is one of the longer geologic periods, covering some 72 million years between about 136 and 64 million years before the present (Casey, 1964).The Cretaceous System is customarily divided into Lower and Upper Cretaceous series, which are subdivided into six stages each (TABLE 1).These stages were first recognized in western Europe and subsequently extended around the world; they are now operationally defined by ammonite zones of the Tethyan province.Continental or near-shore marine sediments favorable for palynological