The palaeogeographical impact on the biodiversity of marine faunas during the Ordovician radiations

Diversification is a key property of life. Building on John Phillips' (1860) classic, iconic curve, Phanerozoic biodiversity trajectories have been based, subsequently, on the availability of additional and renewed sets of data and increasingly sophisticated analytical methods. Using relatively few single sources of data from global databases, the shapes of recent biodiversity curves for Ordovician biotas have predictably converged promoting acceptance of discrete events, aligned with relatively few peaks and discrete drivers. There has been a resistance to investigate under the curves and examine the many and varied causes of biodiversity. Most of the data available pertains to the most abundant part of the benthos, the brachiopods, and more especially their occurrences in Baltica and Laurentia together with South China. Exploration of several regional datasets, deconstructed from global curves, for some key fossil groups indicates the regions that do have their own distinctive biodiversity signals, usually associated with low-latitude settings, but also highlights significant gaps in our knowledge.