The ultrastructure of angiosperm pollen from the Lower Cenomanian of the Morondova Basin, Madagascar

Abstract

Samples collected from Cretaceous sediments of the Morondova Basin, southwest Madagascar yielded a palynoflora composed of spores of ferns and fern allies, pollen of gymnosperms and angiosperms, and dinoflagellates. In addition, a diverse fauna of ammonites was recovered along with the microflora. The species of dinoflagellates and ammonites suggest an Early Cenomanian age. Ninety-two percent of the microflora is comprised of fern spores and gymnosperm pollen. Approximately twenty species of angiosperm pollen comprise 3.6% of the flora, a majority of which are monosulcate and disulcate, including Clavatipollenites, Retimonocolpites, and Liliacidites. Single occurrences of tricolpates and tricolporates are also recorded. The low abundance of angiosperms, and the taxonomic position of the angiosperm pollen are more reminiscent of Lower Cretaceous palynofloras from the Barremian-Albian. The low abundance of angiosperms and high diversity relative to the ferns and gymnosperms suggest that angiosperms arrived on Madagascar by long distance dispersal.