Paleobotany supports the floating mat model for the origin of Carboniferous coal beds

A review of the history of the debate on origin of Carboniferous coal shows the priority that autochthonists have placed on paleobotanical data and interpretation. New data and methodology are offered here for interpreting the paleobotany and paleoecology of dominant Carboniferous coal plants: tree lycopsids and the tree-fern Psaronius. Lycopsid and tree-fern anatomies are characterized by air-filled chambers for buoyancy with rooting structures that are not suited for growth into and through terrestrial soil. Lycopsid development included boat-like dispersing spores, establishment of abundant buoyant, photosynthetic, branching and radiating rhizomorphs prior to upright stem growth, and prolonged life of the unbranched trunk prior to abrupt terminating growth of reproductive branches. The tree fern Psaronius is now understood better than previously to have had a much thicker, more flaring, and further spreading outer root mantle that formed a buoyant raft. Its increasingly heavy leaf crown was counterbalanced by forcing the basally rotting cane-like trunk and attached inner portion of the root mantle continually deeper underwater. Lycopsids and tree-ferns formed living floating mats capable of supporting the trunks. Paleobotany of coal plants should now be best understood as supporting a floating raft that deposited the detritus that now forms Carboniferous coal beds.