Space-time equivalence in the fossil record, with a case study from Pleistocene Australia

Abstract Ecological processes operating across the spatial scale can be equivalently found operating across the temporal scale. Such processes may affect community structure and species richness relationships in ways that can be analysed using the fossil record. The best studied involve the combination of the Species-Area-Relationship and the Species-Time-Relationship into a single space-time equivalence of species richness. This equivalence has been recorded in modern and fossil systems, providing insights into underlying ecological processes controlling species turnover through space and time. The analysis of space-time equivalence has received less attention for community structure, and we outline a framework wherein this could be examined. The inclusion of fossil data to investigations into space-time equivalence are important for revealing emergent properties of ecosystems that are not possible using only modern ecological data. They reveal complexities in the nature of the equivalence across distinct geographical and temporal thresholds and are impacted by environmental heterogeneity. In particular, the examination of space-time equivalence for Quaternary systems highlights the uniqueness of the Holocene with respect to the Pleistocene. Understanding how and why species are found together across large spatial and temporal scales can provide information important for conservation efforts; however, the few cases of space-time equivalence reported using fossil records indicates that this remains a poorly studied area in palaeoecology.