CONICET | Buscador de Institutos y Recursos Humanos

Foliar compressions of two species of Ginkgoites Seward from well-known geological units of the Province of Santa Cruz (Argentina) are analyzed for the first time by semi-quantitative Fourier Transform Infrared (FTIR) spectroscopy. The aim of this contribution is focused on the preserved foliar chemistry in order to reveal mesophyll and cuticle chemical structures (functional groups). The fossils consist of compressions with well-preserved cuticles of Ginkgoites skottsbergii Lundbland, 1971 (PiedraClavada/Kachaike Formation, Albian; BA Pb 13850) and Ginkgoites tigrensis Archangelsky, 1965 (Anfiteatro de Ticó Formation, Aptian; BA Pb 11556-11557, 11561, 14880, 14883, 14887-14889). Ginkgoites leaves were spectroscopically analyzed into two sample forms: (1) compressions (including coalified mesophyll and cuticle) and (2) cuticles. Qualitative and semi-quantitative IR-data of Ginkgoites taxa were interpreted considering their epidermal features, the chemical knowledge of the extant Ginkgo biloba leaves and the available paleoenvironmental information from the localities where the parent plants inhabited during the Lower Cretaceous. Compression sample of Ginkgoites skottsbergii has a low intensity of aliphatic compounds whereas the contribution of aromatic structures is dominant. These results are mainly related to the presence of a thin aliphatic cuticle and phenolic compounds in the mesophyll tissues as it was revealed for the Ginkgo biloba leaves. In contrast, Ginkgoites tigrensis compressions (and the corresponding cuticle sample) have a predominantly aliphatic composition with relatively low contents of aromatic compounds. This is likely due to a high degree of natural oxidation in G. tigrensis compressions as a consequence of the intense volcanic activity during the Aptian sedimentation in Patagonia. *Contribution to project ANPCyT PICT 2015-2206.