[Past]The end-Permian mass extinction coincided with inhospitably high temperature

The earth has been through several extinction events during the past 4.6 billion years...

The Permian-Triassic extinction event has been described as "mother of all extinction",which occurred 252.28 million years ago with great biodiversity loss. There were up to 96% of all marine species and 70% of terrestrial vertebrate species becoming extinct. It is the only known mass extinction of insects. Some 57% of all families and 83% of all genera became extinct. Several mechanisms of the massive extinctions  have been proposed, a gradual environmental change of earlier phase and more catastrophic events (siberian eruptions of CO2)during latter phase. [1]

One recent research [2] proposes that the end-Permian mass extinction and the near-absence of equatorial terrestrial fauna and flora during early Triassic are coincided with thermal maxima.

Figure 1: Early Triassic paleogeography showing rare equatorial occurrence of tetrapod,ichthyofauna and fish.[2]

Figure 2: They used both conodont apatite* oxygen isotope ratio and carbon isotope ratio as proxies reconstructing Late Permian to Middle Triassic equatorial sea water temperatures. The entire Early Triassic record indicates temperatures in excess of Modern Equatorial  Sea Surface Temperatures (annual mean SST).Furthermore, biodiversity of major marine groups and temperatures trends showing inverse relationship: low diversity in Griesbachian and Smithian correlates with peak temperature, whereas peak diversity corresponds to cool climate around the Dienerian-Smithian boundary.[2]

In summation, Sun et al. have examined the relation between global warming and extinction in the Early Triassic. The equatorial Pangea "tetrapod gap " and end-Permian to Middle Triassic global "coral gap"  indicates that lethally temperature conditions could progressively force fauna and floral to vacate the tropics and move to higher latitudes. Together with the rapid temperature rise, other synergetic factors  such as the spread of marine anoxia, may also have profound influence on marine extinction.  

References:
[1]Wikipedia: permian-triassic extinction event

[2] Lethally Hot Temperatures During the Early Triassic Greenhouse, Yadong Sun et al., Science, vol 338, 19 October, 2012.

* conodonts are extinct chordates resembling eels, being known from enigmatic tooth-like microfossils a proxy for thermal alteration in the host rock. wikipedia