Fossil Floral Assemblages in the East Coast Gondwanas - A Critical Review

Palynological investigations carried out during recent years from the Coastal Gondwana sediments have necessitated rethinking on earlier age assignments made on the basis of mega plant fossils.

The Sriperumbudur Beds, Raghavapuram and Vemavaram Shales, Sivaganga Beds and Athgarh Sandstones were dated as Late Jurassic on the basis of Ptilophyllum flora occurring in them and the absence of Weichselia and Onychiopsis. Foraminiferal evidences ascribed an Early Cretaceous age. This discrepancy between plant and animal fossil evidences was attributed to differential evolutionary rates. An Early Cretaceous age assignment is now favoured on the basis of the occurrence of important taxa of stratigraphic value such as: Impardecispora purverulentus, and/or I. apiverrucata, Crybelosporites stylosus, Polycingulatisporites reduncus, Ischyosporites crateris, Aequitriradites spinulosus, Microcachryidites antarcticus, and Staplinisporites caminus.

The plant megafossil assemblage, though distinct; might not be representative or complete. The age cannot be assigned on negative evidences such as the absence of certain fossils. The frequently mentioned discrepancy in age inferred from faunal and floral evidences appears a fallacy. The incompleteness of the evidence, either faunal or floral, is a reality and should be ascribed to our inability to find forms rather than their actual absence.