Researchers reconstruct biodiversity changes during the early Paleozoic Era. Marine biodiversity underwent large and abrupt changes during the early Paleozoic Era. However, the temporal resolution of current Paleozoic biodiversity estimates is insufficient to attribute these changes to potential environmental causes. Christian Rasmussen and colleagues constructed a high-resolution reconstruction of genus-level biodiversity during the first 120 million years of the Paleozoic Era based on fossil occurrences from a paleobiology database. The reconstruction exhibited two distinct bursts of biodiversity accumulation corresponding to the Cambrian Explosion and the Great Ordovician Biodiversification Event (GOBE), separated by 50 million years of slow accumulation. The rapid onset of the latter coincided with equatorial sea-surface temperatures falling to present-day levels, suggesting that 470 million years ago marine biodiversity required a narrow temperature window. Fifteen million years after the start the GOBE, diversity declined sharply in three successive phases corresponding to the End Ordovician mass extinctions, after which biodiversity did not rebound for tens of millions of years. The mass extinctions were associated with the formation of large igneous provinces and abrupt increases in 13C enrichment, consistent with increased volcanic activity. The results suggest that the End Ordovician extinctions may have begun several million years earlier than previously thought, were triggered by increased volcanism, and had a longer lasting impact on global diversity than recognized, according to the authors.
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Article #18-21123: "Cascading trend of Early Paleozoic marine radiations paused by Late Ordovician extinctions," by Christian Mac Ørum Rasmussen, Björn Kröger, Morten Lunde Nielsen, and Jorge Colmenar.
MEDIA CONTACT: Christain Mac Ørum Rasmussen, Natural History Museum of Denmark, University of Copenhagen, DENMARK; tel: +45-21741670; e-mail: < christian@snm.ku.dk >
Proceedings of the National Academy of Sciences