oa Identification of Chitin Preserved in Miocene Fungi using Py-GC×GC-Tofms

Fungi are scarce in fossil record but are studied in deep time as they provide crucial insights into taxonomic and phylogenetic studies. Studies which assign fungal affinity to fossils in deep traces the remains of chitin (a major component of fungal cell wall). Previous studies claim the presence of chitin remnants in Neoproterozoic fossil, assigns its fungal origin using staining methods with other spectroscopic analysis. However they lack chitin-specificity and exclusiveness. Hence the present work has employed a self-reliant approach Py-GC×GC-TOFMS for detailed chemical characterisation and detection of molecular signatures of chitin in Miocene fungi recovered from plant leaf cuticles from the middle Siwalik (late Miocene) sedimentary strata of Himachal Pradesh, western Himalaya, India. The micromorphological study of cuticular fragments from fossil monocot and dicot leaves showed various fungal morphs. The detection of pyrolytic products particularly 3-acetamido-n-pyrones and its methylated derivative in fossils is suggestive of the presence of chitin as these are regarded as chitin-specific proxies. With increased sensitivity and enhanced resolution power of Py-GC×GC-TOFMS, the present work becomes the first report of preserved fungal chitin from Miocene giving conclusive evidence using molecular signatures remains in fossils.