The Permian-Triassic extinction is seen as one of the largest mass extinction in the history of life. According to the McGraw-Hill Dictionary (2003) it can be defined as a mass extinction event marking the division between the Permian Period and the Triassic Period as well as the border between the Palaeozoic and Mesozoic eras. It is estimated to have triggered the extinction of 90% or more of all ocean species, approximately 70% of land vertebrates, and significant extinctions of plants and insects (Erwin, D. H., 1994). Most of what scientists or geologists know about this extinction is based on marine rocks and fossils, and most workers agreed with the estimated loss of at least 80% of marine invertebrate species during less than …show more content…
Erwin, D. H., 1994 and Benton & Twitchett, 2003) that proposed two different percentages (90% & 80% respectively) of marine species that died during the Permian-Triassic extinction. This is due the fact that there are different methods of scaling the percentage of organisms that were affected in this event. Due to increased technological advancements, the accuracy of Palaeontologists’ data is being improved. Figure one gives a visual representation of the number of marine species that was present on Earth through the Phanerozoic. It is also showing the five major extinctions with Permo-Triassic being number three. This extinction caused previously dominant and ecologically important groups to die which basically destroyed many biological communities. According to Chen and Benton (2012) it took several million years for complex communities to recover, both in the oceans and on land. For the estimation of long term global changes in biodiversity during past extinction events, Palaeontologists tend to focus on genera or families. This is because the preservations of species are generally in patches while some true biological species are hard to identify from fossil