Interrelatedness of Biota Revealed in Fossil Trees from the Permian Fossil Forest of Northern Tocantins, Central-North Brazil

While knowledge about the paleobiology of plants has increased considerably, knowledge of the various interactions between trees, climbers, epiphytes, and other coexisting organisms has unfortunately remained limited. Besides morphology, anatomy, reproduction of plants, or even composition and distribution of their communities in space and time, only a thorough study of ecological aspects, the interrelatedness of all organisms, will lead to an all-encompassing understanding of ancient forests. In this contribution, we examine diverse interactions between plants, animals, and putative microorganisms from Permian rocks of northern Tocantins state, central-north Brazil. The plant fossils derive from sedimentary strata of the Parnaíba Basin and are anatomically preserved as siliceous petrifactions. As major representatives of tropical seasonally influenced environments, these plants grew on mineral substrates. Their remnants comprise stems, branches, and roots of tree ferns, sphenophytes, and gymnosperms. Close-fitting or densely interwoven among each other, the plant organs and their various connections to other organisms contribute to the knowledge of multifaceted synecological relationships within the Northern Tocantins Fossil Forest. In some cases, however, the patchy fossil record must be treated with caution. Considering the identification of decay patterns in fossil wood, we are reliant on comparisons with modern plants because organic remains mostly lack in the petrifactions. Such comparisons are centered by the compartmentalization concept focusing on patterns of wood reaction or partial decomposition in living trees, which mainly result from injuries or defense against the spread of pathogens. Though still consisting of a few glimpses into a usually hidden microworld, the unexpected diversity of organism interactions provides new insight into structure, function, and variety of riparian environments in low-latitude Southern Hemisphere regions.