Differential morphographic identity of Gondwanic palynomorphs

Abstract

The exine structures, bauplan and germinal apertures are the basic characters for the morphographic identification of fossil spores and pollen, The apparent but unreal form-similarities or some bisaccate pollen taxa of Sporae dispersae from Gondwanaland on one hand and those in the contemporary Euromerian sequences on the other, have been sorted out in this paper. Trends of different exine structures and saccus organizations have been identified in pollen. This concept has been exemplified by the fact that the pollen taxa Lunatisporites, Lueckisporires and Klausipollenites or the north possess mostly imperfect reliculae, compactly placed grana, columnar elements, rodlets, vermiculae, verrucae or similar elements mixed together, rounded or multifaceted islands or various shapes and sizes, incomplete or even isolated closely packed muri as exinal elements which make the infra-structure or the sexine in the corpus. In contast to this trend, the major pattern or exine structure in apparently similar taxa or the Gondwanaland is different; most of the pollen groups exhibit perfectly infrareticulate structure on corpus with complete muri and distinct meshes. Such a differential morphographic identity may lead to a more rational model of the palaeo-phytogeography based on palynofossils, because the genuine similarities and differences could be effectively used in delimiting the floral provinces. The distinctions in the mother vegetations, which have had produced pollen and spores in two regions, corroborate the distinctions in the groups of palynotaxa discussed here. This paper proposes the theory or the Apparent Form Similarity (AFSIM factor) and highlights certain lines of differentiation amongst the similar-looking but basically different spore-pollen components produced by unrelated plant groups. Some aspects of palynofloral distribution vis-a-vis climatic changes through Gondwana have also been discussed.