The Hirnantian (Late Ordovician) and end-Guadalupian (Middle Permian) mass-extinction events compared

Abstract

The so‐called Big Five mass extinctions of the Phanerozoic include two prominent Palaeozoic episodes: the end‐Ordovician and end‐Permian events, both with large biodiversity loss. We consider that the end‐Ordovician (Hirnantian) extinction could be best compared to the Middle Permian end‐Guadalupian (=Capitanian) extinction, rather than to the end‐Permian (Permo‐Triassic boundary; PTB) extinction. The end‐Guadalupian extinction, ca. 8 Myr before the PTB extinction, occurred as an independent episode under extremely unique global setting with the lowest sea level and lowest Sr isotopic ratios in seawater of the Phanerozoic. Multiple similarities exist between the end‐Ordovician (Hirnantian) and the end‐Guadalupian (Capitanian) events, such as the preferential elimination of sessile biota in the tropics, a global sea‐level drop and secular changes in seawater C and Sr isotope ratios, occurring under global cooling. The limited development of land vegetation suggests that the Ordovician extinction was restricted solely to the marine realm, with no prominent damages on land, and no large igneous province (LIP) recognized in the Ordovician. The comparison indicates that the two extinctions of the Hirnantian and of the Capitanian have been essentially triggered by similar causes/processes; nonetheless, biotic responses were different, owing to the more oxygenated status of surface environments in the Permian after the mid‐Palaeozoic terrestrialization.

The Capitanian Minimum: A Unique Sr Isotope Beacon of the Latest Paleozoic Seawater

“…On the other hand, the onset of the Capitanian Sr minimum was during a cold climate with the lowest Phanerozoic sea level, and it continued until the GLB, which roughly corresponded to the termination, rather than in the middle, of the LPIA (Figure 2). As to the coeval global cooling/ sea-level decrease and Sr isotope minimum, a similar observation was confirmed also for the end-Ordovician timing (Isozaki and Servais, 2018).…”

“…The seawater 87 Sr/ 86 Sr changes, the minimum or the maximum, seem to coincide with several extinction events, e.g., the end-Ordovician, the end-Guadalupian, and the end-Permian (Figure 1). Recently, various similarities were recognized between two major extinction-related episodes in the Paleozoic; i.e., the Hirnantian (end-Ordovician) and Capitanian (end-Permian) events, because both episodes commonly recorded the preferential removal of sessile biota in the tropics, global sea-level drop, negative excursion of carbon isotopes, and end of long-term geomagnetic polarity interval (Isozaki and Servais, 2018;Isozaki, 2019). This may promote further research on other cooling-relevant extinction events and coeval changes in Sr isotope signatures in global oceans.…”

Contextualizing the Onset of the Great Ordovician Biodiversification Event

“…The Permian mass extinction is still considered the most significant, ‘the great dying’, followed by the Ordovician extinction event. Isozaki & Servais () have compared these two major extinction events, but conclude that the end Ordovician extinction is more comparable to the extinction that occurred during the middle Permian, rather than the end Permian extinction. The understanding of the Ordovician radiation requires better knowledge of the oceanographic circulation patterns and biomass production in the oceans.…”

Sulfur and carbon isotopic systematics of Guadalupian‐Lopingian (Permian) mid‐Panthalassa: δ34S and δ13C profiles in accreted paleo‐atoll carbonates in Japan

“…The initial major decline of Permian, during which nearly 60 % of marine invertebrate species became extinct, occurred immediately before the G-LB (Stanley, 2016). Although the G-LB extinction has been overlooked for years in the great shadow of the P-TB mass extinction, its significance has recently drawn more serious attention (Bond et al, 2010;Isozaki, 2009;Isozaki & Servais, 2018;Jin et al, 2006).…”