TAPHONOMIC CHANGES AND DECOMPOSITION PATHWAYS OF MICROBIAL CONSORTIUMS

Early life on Earth consists of microbial life. Actualistic experiments have previously investigated the changes in morphology many microorganisms experience prior to, and during, the fossilization process. By examining taphonomic changes, we can compare changes to morphology in extant microorganisms to the morphologies preserved in the rock record. Previous studies have used monocultures of cyanobacteria, and green or red algae in their experiments; however, microbial mats contain more than one taxon of microorganism, which may affect the decomposition pattern and ultimate preservation of the mat textures and microbes.

Here we present an actualistic taphonomic study of microbial consortiums, one cyanobacteria consortiums, a green algae consortium, and a microbial mat. During decomposition, microbial morphologies were ranked on a scale of “good,” “fair,” and “poor,” and the results were plotted on ternary diagrams. The trajectory of the decomposition pathways for each consortium is similar to the modeled pathways observed by Manning-Berg et al. (2021). Our results suggest that filamentous organisms decay differently than coccoidal organisms in the same consortium. In each experiment, filament morphologies resemble a non-uniform decomposition model where faster decomposition occurs in intact individuals, whereas coccoidal morphologies follow a time-dependent decomposition pathway.