Average generic orthide diversities and total percentages for the Ordovician-Silurian of the Greater Iapetus Ocean Region (Table 1). The columns "average number of genera" contain the average number of genera according to geographic range, e.g. orthide genera found on three plates groups during each stage of the investigated temporal interval comprise 10.4% of the total dataset, corresponding to an average generic diversity of 7.23 genera for every stage of the Ordovician and Silurian. The Min % and Max % are the minimal and maximal values encountered for a single stage during the temporal interval (either the Ordovician-Silurian, only the Ordovician or only the Silurian). The averages are calculated based on diversity and distribution values from each stage of the temporal interval in question, with separate calculations for the Ordovician and the Silurian also provided. Note the difference in average generic diversity between the two periods (again at stage level of resolution), which however is not greatly reflected in the spatial distribution (degree of endemicity) of the surviving genera, barring a decrease in the amount of endemic genera.