Abstract
The early Palaeozoic Era records the initial biodiversification of the Phanerozoic. The increase in biodiversity involved drastic changes in taxon longevity, and in rates of origination and extinction. Here, we calculate these variables in unprecedented temporal resolution. We find that highly volatile origination and extinction rates are associated with short genus longevities during the Cambrian Period. During the Ordovician and Silurian periods, evolutionary rates were less volatile and genera persisted for increasingly longer intervals. The 90%-genus life expectancy doubled from 5 Myr in the late Cambrian to more than 10 Myr in the Ordovician–Silurian periods. Intervals with widespread ecosystem disruption are associated with short genus longevities during the Cambrian and with exceptionally high longevities during the Ordovician and Silurian periods. The post-Cambrian increase in persistence of genera, therefore, indicates an elevated ability of the changing early Palaeozoic marine ecosystems to sustainably maintain existing genera. This is evidence of a new level of ecosystem resilience which evolved during the Ordovician Period.
Highlights
The spectacular early Palaeozoic rise in taxonomic richness of marine ecosystems continues to be a focus point of palaeobiological research [1,2,3,4,5,6,7,8]. It featured two distinct events of accelerated biodiversity accumulation, namely the Cambrian explosion (CE) and the Great Ordovician Biodiversification Event (GOBE). It contained a number of major crises during the Late Ordovician mass extinctions (LOME) [8]
A growing body of evidence suggests that the timing and intensity of the early Palaeozoic biodiversity accumulation was associated with changes in global temperature and oxygen levels [8,9,10,11,12,13]
Our results allow for a differentiation between taxonomic turnover and genus persistence, that again enables an evaluation of time-specific ecosystem resilience as a factor of biodiversity accumulation
Summary
The spectacular early Palaeozoic rise in taxonomic richness of marine ecosystems continues to be a focus point of palaeobiological research [1,2,3,4,5,6,7,8] It featured two distinct events of accelerated biodiversity accumulation, namely the Cambrian explosion (CE) and the Great Ordovician Biodiversification Event (GOBE). Rates of origination and extinction determine the probability of a taxon (here, a genus) to survive until a time t [29,30] This relationship should not lead to the conclusion that analyses of longevity and evolutionary rates are redundant. Our results allow for a differentiation between taxonomic turnover and genus persistence, that again enables an evaluation of time-specific ecosystem resilience (i.e. the ability of a system to absorb changes and still persist, sensu Holling, [32]) as a factor of biodiversity accumulation
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