Figure 2. Rates of endemic orthide genera in percent correlated with time for the Ordovician-Silurian for the GIOR (Laurentia Major, Baltica Major, Avalonia Major, Siberia, European massifs [Bohemia, Armorica, Iberia and Apulia] and Core Gondwana [South America and Africa]). The results are summed to 100%. Note that the term plate group refers to the fact that e.g., Laurentia Major was composed of several components, as were the European massifs.