Abstract
The hypothesis of the Great Evolutionary Faunas is a foundational concept of macroevolutionary research postulating that three global mega-assemblages have dominated Phanerozoic oceans following abrupt biotic transitions. Empirical estimates of this large-scale pattern depend on several methodological decisions and are based on approaches unable to capture multiscale dynamics of the underlying Earth-Life System. Combining a multilayer network representation of fossil data with a multilevel clustering that eliminates the subjectivity inherent to distance-based approaches, we demonstrate that Phanerozoic oceans sequentially harbored four global benthic mega-assemblages. Shifts in dominance patterns among these global marine mega-assemblages were abrupt (end-Cambrian 494 Ma; end-Permian 252 Ma) or protracted (mid-Cretaceous 129 Ma), and represent the three major biotic transitions in Earth’s history. Our findings suggest that gradual ecological changes associated with the Mesozoic Marine Revolution triggered a protracted biotic transition comparable in magnitude to the end-Permian transition initiated by the most severe biotic crisis of the past 500 million years. Overall, our study supports the notion that both long-term ecological changes and major geological events have played crucial roles in shaping the mega-assemblages that dominated Phanerozoic oceans.
Highlights
The hypothesis of the Great Evolutionary Faunas is a foundational concept of macroevolutionary research postulating that three global mega-assemblages have dominated Phanerozoic oceans following abrupt biotic transitions
We demonstrate that Phanerozoic oceans sequentially harbored four global mega-assemblages that scale up from lower-scale biogeographic structures and are defined by shifts in dominant faunas across the major biotic transitions in Earth’s history
Similar standard network representations, including bipartite networks (Fig. 1A) and one-mode projections (Fig. 1B) that are based on pairwise relationships and capture first-order dependencies in the raw data, have been central to network-based macroevolutionary research[6,21,22,25,26]
Summary
A multilayer network representation of the Earth-Life System. We could have constructed a simple network representation of the fossil record by using physical nodes to represent its components, the fossil taxa and the geographic areas where they have been described, and links between them to indicate their relationships[25]. Similar standard network representations, including bipartite networks (Fig. 1A) and one-mode projections (Fig. 1B) that are based on pairwise relationships and capture first-order dependencies in the raw data, have been central to network-based macroevolutionary research[6,21,22,25,26]. These standard network representations of the fossil record ignore the time-constrained relationships in the underlying paleontological data[15] (Supplementary Data 1). Clustering methods applied to standard network representations fail to capture the higher-order temporal structures that can emerge in multilayer networks describing temporal data[28,29]
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