A large (approximately 0.9%), abrupt global decrease in the ratio of the stable isotope 13 C to that of 12 C, coincides with this extinction, and is sometimes used to identify the Permian–Triassic boundary in rocks that are unsuitable for radiometric dating.
Esta extinción coincide cun decrecemento grande (aproximadamente o 0,9%), abrupto global na proporción de isótopos estables 13 C e 12 C, e é ás veces usado para identificar o límite Permiano-Triásico en rochas que non son axeitados para a datación radiométrica.