Paleogeography This geological evidence is only one piece of the puzzle and only gave paleontologists some clues regarding the changing environmental conditions that played a role in the Devonian extinction. Examinations of the changing paleogeography during this time also shed light on factors that may have affected the placoderms. The world map of the Devonian looked very different from the world map today. Things were moving towards the formation of Pangea, which meant that continents were coming together. The surveys written by Friedman and Sallan and Young discussed the role that the shifting of the continents had on the placoderms. This change in the orientation of the continents, specifically the movement of Euamerica and Gondwana closer together, started to close the large ocean that separated the two continents. It is safe to assume that this change in the orientation of the continents would have meant trouble for the organisms that lived in the affected area. Throughout the fossil record there are examples of changing continents causing whole groups of organisms to go extinct, (a glaring example of this is the formation of the isthmus of Panama). From these other examples paleontologists can hypothesize the effects that this change in the orientation of the continents would have had on organisms such as the placoderms. …show more content…
The evolution of advantageous traits in these two taxa would have made it much easier for them to prey on the placoderms. In addition to predation, the new adaptations exhibited by the ray-finned and cartilaginous fishes could have make them more efficient at capturing prey items that the placoderms may have had sole access to in the past (Carr, 1995). Pressure by predators as well as competitive pressure would have made it much harder for the placoderms to deal with other changes in the