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Silurian trilobite alpha diversity and the end-Ordovician mass extinction

  • Jonathan M. Adrain (a1), Stephen R. Westrop (a2), Brian D. E. Chatterton (a3) and Lars Ramsköld (a4)


Following the end-Ordovician extinction, global clade diversity of Silurian trilobites dropped to about half of Ordovician levels. Although clade diversity failed to recover, this extinction had surprisingly little long-term impact on the number of trilobite species that occupied local habitats (alpha diversity). A new compilation of data from Laurentia and other continents indicates that Silurian trilobite alpha diversities in all major environments were comparable to those of the Late Cambrian and Ordovician; shallow subtidal diversity reached an all-time high during the Late Ordovician. The profound differences in patterns at local and global levels demonstrate the necessity for a hierarchical approach to analyses of diversity. Factors governing global clade diversity are lodged at hierarchical levels beyond those controlling local species richness and must be sought in studies of between-habitat (beta) or geographic (gamma) diversity.



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Silurian trilobite alpha diversity and the end-Ordovician mass extinction

  • Jonathan M. Adrain (a1), Stephen R. Westrop (a2), Brian D. E. Chatterton (a3) and Lars Ramsköld (a4)


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