Structural and chemical features of seed fossils from Paleozoic and Mesozoic sedimentary strata

Abstract

In this paper we report novel comparative structural-chemical studies of chemofossils from Paleozoic and Mesozoic seeds. The chemofossils had well-preserved organic matter with a high content of carbon and oxygen. It is shown that the high preservation of the coats of Paleozoic seeds resulted from the reducing environment of their fossilization, which is confirmed by the presence of inclusions of pyrite. IR and EPR spectra of the samples indicate that the chemofossils were of an aromatic nature, and the structural fragments had oxygen-containing functional groups. The Early Carboniferous seeds coats have paramagnetic properties conditioned by the presence of phenoxyl radicals. The chemical structure of the samples was reconstructed using pyrolytic chromatography–mass spectrometry and it was shown that the Early Carboniferous and Cretaceous seeds coats included relicts of different types of lignins. The lignin nature of the studied samples was confirmed by EPR signals of phenoxyl radicals with characteristics typical of natural lignins. We concluded that the Early Carboniferous seed coats contain unmethoxylated polymers of p-coumaric-catechyl type.