Functional groups and elemental analyses of cuticular morphotypes of Cordaites principalis (Germar) Geinitz, Carboniferous Maritimes Basin, Canada

Well-preserved cuticles were isolated from Cordaites principalis (Germar) G einitz leaf compressions, i.e., foliage from extinct gymnosperm trees Conif erophyta: Order Cordaitales. The specimens were collected from the Sydney, Stellarton and Bay St. George subbasins of the once extensive Carboniferous Maritimes Basin of Atlantic Canada. Fourier transformation of infrared spe ctra (FTIR) and elemental analyses indicate that the ca. 300-306-million-ye ar-old fossil cuticles share many of the functional groups observed in mode rn cuticles. The similarities of the functional groups in each of the three cuticular morphotypes studied support the inclusion into a single cordaite -leaf taxon, i.e., C. principalis (Germar), confirming previous morphologic al investigations. Vitrinite reflectance measurements on coal seams in clos e proximity to the fossil-bearing sediments reveal that the Bay St. George sample site has the lowest thermal maturity, whereas the sites in Sydney an d Stellarton are mon mature. IR absorption and elemental analyses of the co rdaite compressions corroborate this trend, which suggests that the coalifi ed mesophyll in the leaves follows a maturation path similar to that of vit rinite. Comparison of functional groups of the cordaite cuticles with those from certain pteridosperms previously studied from the Sydney Subbasin sho ws that in the cordaite cuticles highly conjugated C-O (1632 cm(-1)) bands dominate over carbonyl stretch that characterizes the pteridosperm cuticles . The differences demonstrate the potential of chemotaxonomy as a valuable tool to assist distinguishing between Carboniferous plant-fossil groups. Pu blished by Elsevier Science B.V.