Pollen Morphology of Angiosperms and Palaeofloristic areas and provinces at the boundary of the Cretaceous and Paleogene

Abstract

The establishment of natural affinity between ancient angiosperms and taxa of recent flora can be based on palynomorphological studies. The structure, number and distribution of apertures are important features.
 At the beginning of the Late Cretaceous period angiosperms had pollen with primitive but already distinct apertures. Their relationship with Salicales, Fagales, Platanales, Eucommiales (?), can be established.
 During the Late Cretaceous, pollen type with syncolpate apertures (Duplospores-Sporopollis-Sincolporites) become differentiated, which may be linked with the Santalales, Myrtales and Sapindales. In the Upper Senonian-Paleocene pollen with extremely complicated and varied apertures become differentiated partially with inequipolar symmetry (Aquilapollenites, Pentapollenites, Pemphixipollenites, Betpakdalina, Kryshtofoviana, Porotrichotomosulcales types). Some taxa of these may be associated with the families Loranthaceae, Olacaceae, Simarubaceae, Palmae (?), Euphorbiaceae etc. Genera and species included above have narrow stratigraphic ranges and distinctly outlined areals.
 To the same period belongs the differentiation of pollen type with a three-equatorial aperture (Normapolles, Proteacidites, Triorites and Triatriopollenites), which are links with morphological types of pollen of Proteaceae, Myricaceae, Casuarinaceae Fagaceae, Rubiaceae Ulmaceae, Juglandaceae and Betulaceae.
 With the help of morphological groups, we succeeded to establish sequential stages and phases in the history of the development of angiosperm flora and determine their role in the formation of botanical-geographical regions and provinces. During the Late Cretaceous-Paleogene boundary period relationship is established between Pacific and Atlantic floristic areas of Eurasia on one hand the North America and the continents of the Southern Hemisphere on the other.