End-Permian extinction

—It will not be extraterrestrial impacts, disease, or other extrinsic agents that will cause the extinction of Man, but rather the collapse of his artificial economy. We argue that there is no productive category of the economy beyond the Service Sector in which to shift the global work force. As the Agriculture, Manufacturing, and Service Sectors continue to shed workers in a bid to reduce costs, this inevitably feeds Unemployment. A global economic regime in which an ever decreasing pool of workers subsidizes an ever growing army of unemployed is axiomatically unsustainable and conduces to system breakdown. That fateful day, profit-minded agricultural corporations will have no further incentive to produce food or deliver it to the cities.

This diagram show the rise and fall of global temperatures during the last 540 million years.  Scotese (2016) describes how this curve was made.  It replaces the curve published in Scotese et al., (1999).

PETM= Paleocene-Eocene Thermal Maximum (55.8 Ma), EEOC = Early Eocene Climatic Optimum (54 Ma – 46 Ma), MECO = Mid-Eocene Climatic Optimum(42 Ma), EOT = Eocene-Oligocene Transition (40 Ma – 33 Ma), MMCO=Mid-Miocene Climatic Optimum (15Ma – 13Ma), LGM = Last Glacial Maximum (21,000 years ago), 2016 = Modern MAT, PAW = Post-Anthropogenic Warming .  White stars indicate rapid cooling episodes (Stoll-Schrag Events26) at 160Ma, 127Ma, 97Ma, 91Ma, 71Ma, and 65 Ma).  Black stars represent rapid warming episodes (Kidder-Worsley Events16) at (Present-day, 15Ma, 43Ma, 56Ma, 65Ma, 93Ma, 120Ma, 183Ma, 200Ma, 251Ma, 300Ma, 359Ma, 374Ma, 444Ma, 499Ma, 520Ma, and 542 Ma).

Please cite as:  Scotese, C.R., 2015.  Phanerozoic Temperature Curve, PALEOMAP Project, Evanston, IL.

To learn more about how this curve was produced see:
Scotese, C.R., 2016.  Some thoughts Global Climate Change: The Transition from Icehouse to Hothouse, in Scotese, C.R., Earth History: The Evolution of the Earth System as Revealed through Plate Tectonics, Paleogeography, Paleoclimate, and the Evolution of Life, PALEOMAP Project, (in preparation), Evanston, IL.

The Permian and Triassic were key time intervals in the history of life on Earth. Both periods are marked by a series of biotic crises including the most catastrophic of such events, the end-Permian mass extinction, which eventually led to a major turnover from typical Palaeozoic faunas and floras to those that are emblematic for the Mesozoic and Cenozoic. Here we review patterns in Permian-Triassic bony fishes, a group whose evolutionary dynamics are understudied. Based on data from primary literature, we analyse changes in their taxonomic diversity and body size (as a proxy for trophic position) and explore their response to Permian-Triassic events. Diversity and body size are investigated separately for different groups of Osteichthyes (Dipnoi, Actinistia, 'Palaeopterygii', 'Subholostei', Holostei, Teleosteomorpha), within the marine and freshwater realms and on a global scale (total diversity) as well as across palaeolatitudinal belts. Diversity is also measured ...

Three successive plant assemblages are studied from the latest Vyatkian (Changhsingian)–basal Vetlugian (terminal Changhsingian–Induan) of the Volga–Dvina river basins, European Russia, correlated with marine and non-marine transitional PTB intervals elsewhere. The rise of conifers, a decrease of leaf size in the persistent Late Permian morphotaxa, and preliminary data on stomatal index indicate cooling in the terminal Vyatkian followed by an increase of atmospheric CO2 levels.

The end-Permian mass extinction is now robustly dated at 252.6 ± 0.2 Ma (U–Pb) and the Permian–Triassic (P–T) GSSP level is dated by interpolation at 252.5 Ma. An isotopic geochronological timescale for the Late Permian–Early Triassic, based on recent accurate high-precision U–Pb single zircon dating of volcanic ashes, together with calibrated conodont zonation schemes, is presented. The duration of the Early Triassic (Induan + Olenekian stages) is estimated at only 5.5 million years. The duration of the Induan Stage (Griesbachian + Dienerian sub-stages) is estimated at ca. one million years and the early Olenekian (Smithian sub-stage) at 0.7 million years duration. Considering this timescale, the ‘‘delayed” recovery following the end-Permian mass extinction may not in fact have been particularly protracted, in the light of the severity of the extinction. Conodonts evolved rapidly in the first 1 million years following the mass extinction leading to recognition of high-resolution conodont zones. Continued episodic global environmental and climatic stress following the extinction is recognized by multiple carbon isotope excursions, further faunal turnover and peculiar sedimentary and biotic facies (e.g. microbialites). The end-Permian mass extinction is interpreted to be synchronous globally and between marine and non-marine environments. The nature of the double-phased Late Permian extinction (at the Guadalupian–Lopingian boundary and the P–T boundary), linked to large igneous provinces, suggests a primary role for superplume activity that involved geomagnetic polarity change and massive volcanism.

May, A. (1996a): Relationship among sea-level fluctuation, biogeography, and bioevents of the Devonian: an attempt to approach a powerful, but simple model for complex long-range control of biotic crises. - Geolines, 3: 38-49, 2 figs.; Praha.

ABSTRACT. Connections among changing sea-level, development of marine biogeography and appearance of bioevents in Devonian times are emphasised. Decreasing Devonian provincialism of the marine fauna reflects rising sea-level of global ocean. Whereas the Emsian sea-level lowstand was accompanied by strong provincialism of the marine communities, the Frasnian highstands were linked to an unusual decrease of provincialism. As generally documented, the partial but intensive transgressional events (often related to bioevents) were usually associated with a decrease of the provincialism. The best explanation for the majority of Devonian bioevents is the effect of oceanic anoxia. A model suggested herein operates with a fast transgression related to fast ocean sea-level rise. A direct consequence of this fast transgression was the increased primary biomass production (caused by both increased infiux of nutrients and increased total surface of shallow seas). Decreased oxygen supply of oceans continued this process being caused by the global temperature increase which resulted from the albedo decrease. These consequences of these combined factors produced an oceanic anoxic event which started the extinction processes of the bioevent. The well-documented pattern of intensified biological crises during the Devonian, time-slice by time-slice (from Emsian to Frasnian), is explained as a direct result of decreased provincialism of the marine fauna. Both decrease of the provincialism and increased intensity of the Devonian bioevents can be deduced directly or indirectly from changes of global sea-level. This simply constructed but very complex explanation yields two advantages: first, it needs only very few infiuencing factors, second, it can basically renounce incalculable influences (e.g. meteorite impacts). The suggested concept of oceanic anoxic events can explain also other major bioevents of the Earth history.

KURZFASSUNG: Der Artikel versucht, Zusammenhänge zwischen den Veränderungen des Meeresspiegels, der Entwicklung der marinen Biogeographie und den Bioevents im Devon herauszuarbeiten und zu erklären. Die Entwicklung des Faunen-Provinzialismus im Devon ist ein Ergebnis der Entwicklung des globalen Meeresspiegels. Im Emsium war der Meeresspiegel niedrig und der Provinzialismus der Meeresfauna gross, im Frasnium war der Meeresspiegel hoch und der Provinzialismus sehr gering. Insbesondere einige Trangressions-Schübe, die sich auch als Bioevents bemerkbar machten, führten zu schnellen Abnahmen der Grösse des Provinzialismus. Die beste Erklärung für die meisten devonischen Bioevents ist das Auftreten von ozeanischen anoxischen Events. Das hier vorgestellte Modell setzt bei schnellen Transgressionen an, die durch schnelle Meeresspiegel-Anstiege verursacht wurden. Die Konsequenzen einer schnellen Transgression waren gesteigerte Primär produktion organischer Substanz und geringere Sauerstoff- Versorgung der Ozeane, was zusammen zum ozeanischen anoxischen Event und zum Bioevent führte. Der Umstand, dass die Intensität der Bioevents vom Emsium zum Frasnium zunahm, wird durch die Abnahme des Provinzialismus der Meeresfauna in dieser Zeit erklärt. Sowohl die Entwicklung des Provinzialismus der marinen Fauna als auch das Auftreten und die Intensität der Bioevents im Devon lassen sich direkt oder mittelbar aus der Entwicklung des globalen Meeresspiegels ableiten. Dieser sehr umfassende Erklärungsansatz hat den Vorteil, mit sehr wenigen Einfiussfaktoren auszukommen und auf unkalkulierbare Einwirkungen (wie z.B. Meteoriten-Einschläge) völlig verzichten zu können. Vermutlich ist das hier entwickelte Konzept eines ozeanischen anoxischen Events auch auf andere Bioevents übertragbar.

KEYWORDS: Devonian, Kellwasser Event, ecosystems, biogeography, sea level fiuctuation.

The most profound biotic crisis in the Earth's history, causing the near extinction of both terrestrial and marine life, occurred at the end of the Permian period about 253 Myr ago and marks the Paleozoic^Mesozoic era boundary. The cause of this event is still a matter of vigorous debate, with both brief and catastrophic as well as gradual mechanisms having been proposed. Similar to a recent landmark study, this study uses the U^Pb method on zircons from the uppermost Permian/lowermost Triassic ash fall deposits at Meishan (Zhejiang Province, SE China) in order to examine time and rate constraints for these events. The results of both this study and previous work show that for these ash layers, the effects of Pb loss are combined with varying amounts and sources of inheritance, resulting in an age scatter which prohibits the extraction of a statistically robust age in many cases. Though the effects of Pb loss on the zircons analyzed in this study were reduced by leaching the grains in hydrofluoric acid (as opposed to commonly applied air abrasion) prior to analysis, the presence within a single ash layer of multiple generations of older xenocrysts (in many cases only slightly older than the depositional age) has made quantitative interpretation even more difficult. When these combined phenomena bias individual zircon ages by less than a percent, they are extremely difficult to deconvolute, and, if multi-grain analyses are used, can become impossible to recognize (because of the resulting age averaging). Monte Carlo simulations using actual measurements of individual zircon crystals show that age excursions due to Pb loss and xenocrystic contamination for the Meishan bentonites are easily homogenized to the point of undetectability when replicate analyses of multi-grain zircon samples are compared. Thus this study uses only high-precision analyses of single crystals, whether from our work or that of previous studies. Three main conclusions have emerged. First, our data require a significant increase in the age of the Permian^Triassic boundary by more than 2 myr compared to the previous study, which shifts the age to a value older than 253 Ma. Second, neither our data nor those from previous work can confirm or negate the possibility of a very abrupt biotic crisis. Third, even large suites of very high-quality, single-zircon U^Pb analyses for these tuffs cannot, in most cases, yield objective, reliable, and robust dates with accuracies at the sub-myr level ^ though the temptation to perform arbitrary selection of subsets of the analyses for that purpose is almost irresistible. The last conclusion is not an indictment of zircon U/Pb dating in general (other rocks and other zircon populations can ^ and do ^ behave very differently), and further technical advances will likely improve our ability to prepare grains or sub-grains of adequately enhanced quality for analysis. Consequently, the results of the present study strongly suggest that for problems requiring time-scale accuracy, inferences from zircon U^Pb dating must be based on sufficiently large suites of single-crystal or crystal domain, high-precision analyses (61% error) that are realistically interpreted.

High-resolution organic carbon isotope (δ 13C), Hg concentration and Hg isotopes curves are presented for the Permian-Triassic boundary (PTB) sections at Guryul Ravine (India) and Meishan D (China). The total organic carbon (TOC)-normalized Hg concentrations reveal more intense environmental changes at the Latest Permian Mass Extinction (LPME) and the earliest Triassic Mass Extinction (ETME) horizons coinciding with major δ 13C shifts. To highlight palaeoredox conditions we used redox-sensitive elements and Rare Earth Element distribution. At Meishan, three Hg/TOC spikes (I, II, and III) are observed. Spike I remains after normalization by total aluminum (Al), but disappears when normalized by total sulfur (TS). Spike III, at the base of Bed 26, corresponds with excursions in the Hg/TS and Hg/Al curves, indicating a change in paleoredox conditions from anoxic/euxinic in the framboidal pyrite-bearing sediments (Bed 26) to oxygenated sediments (Bed 27). At Guryul Ravine, four Hg/TOC s...

The Permian–Triassic boundary interval in China comprises a significant record of faunal and floral changes during this important extinction event. Here we discuss the details of palynomorph preservation at the classical Western Guizhou and Eastern Yunnan sections in an effort to expand the stratigraphy and paleontology from these earlier studies.

Until now, the Hiraiso Formation was considered to be entirely of Smithian (early Olenekian, Early Triassic) age, but the discovery of the ammonoid Tirolites cf. ussuriensis in the lower part of the formation on the rocky coast between the Maekawara and Akaushi Ports, Motoyoshi Town, Kesennuma City, in the South Kitakami Belt, Northeast Japan, establishes that this portion is actually equivalent to the upper part of the lower Spathian Tirolites-Amphistephanus Zone (upper Olenekian). The fauna of the Hiraiso Formation, which includes the large bivalve Eumorphotis iwanowi and crinoid ossicles, very much resembles the Tirolites ussuriensis beds in South Primorye, Russian Far East, suggesting a wide distribution of this shallow marine fauna in the low to middle northern latitudes on the western side of the Panthalassa during the early Spathian. Because pre-Spathian deposits contain only small sized species of Eumorphotis and very rare crinoid ossicles, the appearance of large species of...

It has long been recognized that terrestrial floras underwent major and long-lasting changes during the Permian and Triassic, some of which have been attributed to the end-Permian mass extinction. However, these changes are still poorly understood with regard to the late Permian and Early Triassic. In particular, the impact that ecological disturbances around the Permian-Triassic boundary had on the composition and palaeogeographical distribution of land plant communities needs to be scrutinized. We analyse this impact based on fossil floras from across the world, covering the Wuchiapingian to Ladinian time interval. The plant assemblages are assigned to biomes representing particular environmentally controlled community types. Variations in the distribution of biomes between stages indicate shifts in the environmental parameters affecting terrestrial floras, and provide insights into population turnover dynamics. A substantial shift towards increasing seasonality and a reduction of biome diversity occurs in the earliest Triassic and stabilised throughout the Middle Triassic. However, results also show that the stratigraphically and (palaeo-) geographically unequal distribution of sampled localities constitutes an important limitation for this kind of analysis.

May, A. (1997g): Ein Modell zur Erklärung der Bio-Events und der biogeographischen Entwicklung im Devon durch den Meeresspiegel. - Dortmunder Beiträge zur Landeskunde, Naturwissenschaftliche Mitteilungen, 31: 137-174, 5 figs.; Dortmund.

Abstract: The attempt is made, to show and to explain connections between the changing sea-Ievel, marine biogeography, and bio-events within the Devonian. The Devonian development of marine faunal provincialism is the result of changes in global sea-Ievel. Within the Emsian sea-Ievel was low and marine faunal provincialism was strong, while within the Frasnian sea-Ievel was high and marine faunal provincialism was weak. Some particular transgressive intervals made themselves felt as bio-events, conducive to fast decreases in the intensity of provincialism. Starting with the Daleje Event of the Emsian and ending with the Kellwasser Event of the Frasnian, the bio-events are discussed in detail. In this context new data concerning the Middle Devonian of the Eastern Rhenish Massif are presented. The best explanation for most Devonian bio-events is the occurrence of oceanic anoxic events. The model presented here uses fast transgressions caused by rapid sea-Ievel rises (see fig. 1). Fast transgression increased primary biomass production (caused by an increased influx of nutrients and an increased area of shallow sea) and decreased oxygen supply in the oceans (caused by global temperature increase resulting from albedo decrease). Both factors together resulted in the oceanic anoxic event conducive to the bio-event. The fact, that bio-event intensity increased from the Emsian to the Frasnian is explained by the decrease of marine faunal provincialism within this time. Both the development of provincialism and the occurrence and intensity of bio-events within the Devonian can be deduced directly or indirectly from the changes in global sea-Ievel. This comprehensive attempt at explanation has the advantage of needing only a few influencing factors and renouncing incalculable influences (e. g. meteorite impacts). Possibly, the model of oceanic anoxic events presented is also transferable to other bio-events (e. g.: bio-events of the Famennian, Cenomanian/Turonian Event). Kurzfassung: Der Artikel versucht, Zusammenhänge zwischen den Veränderungen des Meeresspiegels, der Entwicklung der marinen Biogeographie und den Bio-Events im Devon herauszuarbeiten und zu erklären. Die Entwicklung des Faunen-Provinzialismus im Devon ist ein Ergebnis der Entwicklung des globalen Meeresspiegels. Im Emsium war der Meeresspiegel niedrig und der Provinzialismus der Meeresfauna groß, im Frasnium war der Meeresspiegel hoch und der Provinzialismus sehr gering. Insbesondere einige Trangressions-Schübe, die sich auch als Bio-Events bemerkbar machten, führten zu schnellen Abnahmen der Größe des Provinzialismus. Die Bio-Events vom Daleje-Event des Emsiums bis zum Kellwasser-Event des Frasniums werden detailliert besprochen. In diesem Zusammenhang werden auch neue Daten zum Mitteldevon des Rechtsrheinischen Schiefergebirges gegeben. Die beste Erklärung für die meisten devonischen Bio-Events ist das Auftreten von ozeanischen anoxischen Events. Das hier vorgestellte Modell setzt bei schnellen Transgressionen an, die durch schnelle Meeresspiegel-Anstiege verursacht wurden (siehe Abb. 1). Die Konsequenzen einer schnellen Transgression waren gesteigerte Primärproduktion organischer Substanz und geringere Sauerstoff-Versorgung der Ozeane, was zusammen zum ozeanischen anoxischen Event und zum Bio-Event führte. Der Umstand, daß die Intensität der Bio-Events vom Emsium zum Frasnium zunahm, wird durch die Abnahme des Provinzialismus der Meeresfauna in dieser Zeit erklärt. Sowohl die Entwicklung des Provinzialismus der marinen Fauna als auch das Auftreten und die Intensität der Bio-Events im Devon lassen sich direkt oder mittelbar aus der Entwicklung des globalen Meeresspiegels ableiten. Dieser sehr umfassende Erklärungsansatz hat den Vorteil, mit sehr wenigen Einflußfaktoren auszukommen und auf unkalkulierbare Einwirkungen (wie z. B. Meteoriten-Einschläge) völlig verzichten zu können. Vermutlich ist das hier entwickelte Konzept eines ozeanischen anoxischen Events auch auf andere Bio-Events übertragbar.

Multiple observations have revealed that environmental disturbances may have been linked to the end-Permian mass extinction and delayed biotic recovery. Biogeochemical constraints on the temporal and spatial changes of oceanic redox chemistry during the Permian–Triassic interval are essential to evaluate global significance of previous hypotheses and to improve our understanding of extinction and recovery processes. To investigate redox ocean chemistry change associated with the end-Permian extinction and subsequent delayed biotic recovery, we examine framboidal pyrites as well as sulfur isotopic compositions of pyrites from the East Greenland Basin. The size distributions of framboidal pyrites in sediments from a continuous section across the Permian–Triassic boundary reveal that sulfidic conditions in water columns were established about 0.7 m above the extinction event in the East Greenland Basin. Our detailed examination of framboidal pyrites challenges a leading hypothesis that euxinia in the photic zone caused the end-Permian ecosystem collapse. We identify several positive and negative S-isotopic shifts before and after the extinction event and demonstrate that a positive S-isotopic shift is not indicative of an abrupt change of redox chemistry in water columns, in contrast to previous claims. The integration of isotope and framboidal pyrite data provides a nearly continuous record of ocean chemistry evolution and new insights into the end-Permian extinction and delayed biotic recovery in the East Greenland Basin.

The age and timing of the Permian-Triassic mass extinction have been difficult to determine because zircon populations from the type sections are typically affected by pervasive lead loss and contamination by indistinguishable older xenocrysts. Zircons from nine ash beds within the Shangsi and Meishan sections (China), pretreated by annealing followed by partial attack with hydrofluoric acid, result in suites of consistent and concordant uranium/lead (U/Pb) ages, eliminating the effects of lead loss. The U/Pb age of the main pulse of the extinction is 252.6  0.2 million years, synchronous with the Siberian flood volcanism, and it occurred within the quoted uncertainty.