Palaeontological data from the Permian-Triassic Bulla section, northern Italy, demonstrate a rapid extinction at this site. This occurs after a negative carbonate carbon-isotope (delta C-13(carb)) shift, consistent with two other northern Italian sites (Val Badia and Tesero). However, conclusion goes against recent reporting that the extinction occurs before the delta C-13(carb) shift. We agree that the shift occurs after the extinction at Jameson Land, east Greenland (a high latitude palaeolocation). However, all other sections show the shift before, or coincident with, the extinction. We suggest that the simplest explanation is a coeval shift in carbonate carbon-isotope shifts, and it follows that the extinction was not. This suggests that the end-Permian extinction crept from region to region. It also suggests that the marine extinction occurred first in high northern latitudes.
Gorjan, P., Kaiho, K., & Chen, Z. (2008). A Carbon-isotopic study of an end-Permian mass-extinction horizon, Bulla, northern Italy: a negative δ13 shift prior to the marine extinction. Terra Nova, 20, 253-258. https://doi.org/10.1111/j.1365-3121.2008.00813.x