Coprolites are traditionally analyzed from a morphological perspective. Few studies exist from an organic geochemical perspective, and most of these consider recent specimens. This study represents an analysis of coprolites from deep time, using both traditional one-dimensional and also two-dimensional gas chromatography-mass spectrometry. We find organic molecules preserved in coprolites from the Triassic, and that both dietary habits of the defecators and paleoenvironment can be interpreted using comparative distributions of biomarker abundances in the coprolites. Steranes having 27 carbon atoms are known to be derived from animal steroids whereas those with 29 carbon atoms are known to be derived from plant steroids. The predominance of steranes with 27 carbon atoms over those with 29 carbon atoms in a non-marine environment was interpreted as evidence for the defecator(s) being predominantly carnivorous or possibly omnivorous. A series of tricyclic terpanes ranging from C19 to C28 was examined to determine the environment. The present study suggests that one or possibly all of the defecators may have been small-medium carnivores that lived in an aquatic or near aquatic setting.

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Molecular dating estimates the origin of the fungal clade to the Pre-Cambrian. Yet, the oldest unambiguous fungal fossils date to the Ordovician and show remarkable diversity and organizational development. Recent studies have suggested that the dates for the emergence of fungi in the fossil record may be pushed back to the Proterozoic. However, the nonspecificity of the methods used in those studies necessitates the employment of a wider variety of analytical techniques that can independently verify the presence of chitin, a crucial prerequisite in the assignment of fungal affinity, particularly of putative fossils from the Pre-Cambrian. In this paper, we propose Py-GC × GC-TOFMS as an example of one such technique. We analyze fungal fossils from the Pliocene. We find that a suite of N-bearing compounds are present in the pyrolysis products of these fossils, from which we suggest that 3-acetamidopyrones and their methylated homologues can serve as specific pyrolytic markers for chitin. We discuss both how this technique can potentially be used to differentiate between biopolymers, including those similar to chitin such as peptidoglycan, and the potential implications of identifying such markers in fossils from deep time. We conclude that Py-GC × GC-TOFMS is a promising technique that can potentially be used alongside, or independent of, staining methods to detect the presence of chitin in fossils.