Prospects for studying continentalization and the origin of terrestrial ecosystems during the late Paleozoic

Benjamin Kobina Asuantsi Otoo^*

• Department of Earth Sciences, Faculty of Science, Carleton University, Ottawa, Canada

The origin of terrestrial ecosystems during the Paleozoic was pivotal in the history of life on Earth. This is a fascinating case for testing hypotheses about how ecological novelty arises at organismal, lineage, and community levels. Here I review research on community assembly and change in deep time and discuss this work in the context of investigating the continentalization of ecosystems. Extensive study of large-scale Phanerozoic trends in taxonomic and autecological diversity, especially in the marine realm, provide an important theoretical framework. However, the interactions between these trends and community-level properties such as stability and species carrying capacity are not as well understood. The growing body of paleo-food web literature has returned ambiguous results, and it is not clear if the bounds of community performance have shifted over time or not. Importantly, these studies are conducted either entirely in the marine realm or the terrestrial realm, but not yet on communities representing the initial expansion of life into nonmarine-and, eventually, terrestrial-habitats. Modern-day systems such as island colonization might provide some useful insights into continentalization in deep time but are effectively instances of terrestrial ecosystems being reproduced using extant terrestrial taxa, not terrestrial ecosystems developing de novo. The timeline of Paleozoic continentalization as currently understood is reviewed. Though the process was already underway, the late Paleozoic (Devonian-Permian) emerges as a key interval for the study of continentalization. Food web modeling methods and hypotheses are discussed. Though challenging, going forward this area of research has great potential to address questions of relevance to paleontologists, neontologists, and ecologists alike.