Opposing Views

It has been suggested that the anoxia, mentioned in the section above, occurred too late to have caused the Permian extinction, and is also insignificant compared to other factors. There is some speculation that there was an unglaciated time at the end of the Paleozoic, due to Pangea moving off the South Pole. Glaciation was apparent in the southern hemisphere from the mid Devonian into the middle Permian because of the landmass over the South Pole, but most of the extinctions occurred at the end of the Permian and into the Triassic when Pangea had moved. This would suggest that glaciation was not a contributing factor to the end Permian extinction.

An explanation for why these different opinions occur is because Pangea was so large and stretched from far up in the northern hemisphere, to low down in the southern hemisphere. As the super continent moved off the south pole it became unglaciated, but the continent encroached on the north pole and ice sheets were formed in the north. This meant that throughout much of the Permian there was fluctuating glaciation between the south and north. In a paper by Hallam and Wignall it is suggested that regression, which is often linked with glaciation, did not occur. Although sea level drop is considered one of the main causes of the extinctions they suggest that evidence from biostratigraphy shows that there was not a regression at all. Although taxa became extinct in end Permian, Salt Range sediments of North Pakistan, there is no discontinuity in deposition. This suggests that regression did not happen at the time of extinction.

Other evidence supporting their hypothesis comes from the Dolomites of northern Italy where no change in deposition can be seen at the end of the Permian.