Pre-Quaternary wood decay ‘caught in the act’ by fire – examples of plant-microbe-interactions preserved in charcoal from clastic sediments

The fossil record contains abundant evidence for the activity of microorganisms in the form of characteristic decay structures within fossil plant remains. Despite an abundance of charcoal in many sedimentary environments, there is little published evidence of such decay structures within charcoal from pre-Quaternary clastic deposits. The present contribution presents some examples of pre-Quaternary charcoal from clastic sediments which exhibit pre-charring decay structures, stratigraphically reaching from the Permian up to the Oligocene. Examples include specimens affected by the principle types of wood rot known from modern ecosystems (i.e. brown-rot, white rot and soft-rot) as well as a peculiar decay pattern resembling an atypical type of white-rot, which is only rarely known from modern wood. Theoretically there are different, so far hypothetical, scenarios which could be used to explain the scarcity of published reports on such material. Besides taphonomical biases directly influencing the sedimentary record of charcoal towards material not affected by microbial decay, it is conceivable that the lack of reports of such material from pre-Quaternary clastic deposits represents a, maybe unintentional, bias introduced by scientists working on pre-Quaternary charcoal.