Knowledge of the posotion of the supercontinent of Laurentia with respect to Gondwana and peri-Gondwanide terranes, such as Armorica, Iberia and Avalonia, is of paramount importance for the proper understanding and quantification of geodynamic events during the Paleozoic. Unfortunately, the paleomagnetic database for the Silurian-Devonian of continents once part of Gondwana is incomplete and provides few constraints on paleogeographic models. The result has been the appearance of several controversial paleogeographic models with very different interpretations for this period. One means of constraining or testing such reconstructions is through comparison with well interpreted and robust biogeographic patterns. One major group of marine invertebrates, the nautiloid cephalopods, is particularly well suited to this task. A significant portion of nautiloid evolution occurred during the Silurian-Devonian, the biogeographic database is large and can be made much better with reasonable effort, analytical techniques are available to provide patterns of exceptional quality, and the spatial distributions of nautiloid cephalopods are now known to have been particularly well controlled by barriers to dispersal of the magnitude easily recognized with proper methods.
