The Middle Permian mass extinction.

The Kapp Starostin Formation, Festningen section, Spitsbergen. The uppermost of the 3 yellow limestone beds records the Middle Permian mass extinction (Credit: Photographer: Dierk Blomeier. For David P.G. Bond and colleagues, GSA Bulletin, 2015.)

The Kapp Starostin Formation, Festningen section, Spitsbergen. The uppermost of the 3 yellow limestone beds records the Middle Permian mass extinction (Photo Credit: Dierk Blomeier. For David P.G. Bond and colleagues, GSA Bulletin, 2015.)

Extinction is the ultimate fate of all species. The fossil record indicates that more than 95% of all species that ever lived are now extinct. Individuals better adapted to environments are more likely to survive and when a species does fail, it is called a background extinction. Occasionally extinction events reach a global scale, with many species of all ecological types dying out in a near geological instant. These are mass extinctions. They were originally identified in the marine fossil record and have been interpreted as a result of catastrophic events or major environmental changes that occurred too rapidly for organisms to adapt.  Mass extinctions are probably due to a set of different possible causes like basaltic super-eruptions, impacts of asteroids, global climate changes, or continental drift.

George Cuvier, the great French anatomist and paleontologist, was the first to suggested that periodic “revolutions” or catastrophes had befallen the Earth and wiped out a number of species. But under the influence of Lyell’s uniformitarianism, Cuvier’s ideas were rejected as “poor science”. The modern study of mass extinction did not begin until the middle of the twentieth century. One of the most popular of that time was “Revolutions in the history of life” written by Norman Newell in 1967.

The fossil record shows that biodiversity in the world has been increasing dramatically for 200 million years and is likely to continue. The two mass extinctions in that period (at 201 million and 66 million years ago) slowed the trend only temporarily. Genera are the next taxonomic level up from species and are easier to detect in fossils. The Phanerozoic is the 540-million-year period in which animal life has proliferated. Chart created by and courtesy of University of Chicago paleontologists J. John Sepkoski, Jr. and David M. Raup.

Biodiversity in the fossil record.  (From Wikimedia Commons)

Over the last 3 decades, mass extinction events  have become the subject of increasingly detailed and multidisciplinary investigations. In 1982, Jack Sepkoski and David M. Raup used a simple form of time series analysis at the rank of family to distinguish between background extinction levels and mass extinctions in marine faunas, and identified five major extinction events in Earth’s history: at the end of the Ordovician period, Late Devonian, End Permian, End Triassic and the End Cretaceous. These five events are know as the Big Five. The most recently identified mass extinction occurred during the Middle Permian, about  262 million years ago, and it was first recognised in the marine realm as a turnover among foraminifera, with fusulinaceans among the principal casualties. The crisis also affected numerous other shallow-marine taxa, including corals, bryozoans, brachiopods, bivalves and ammonoids. Until now, all detailed studies have focused on equatorial sections, especially those of South China. That extinction coincide with the Emeishan large igneous province. But, new data indicates that at the same time there was two severe extinctions amongst brachiopods in northern boreal latitudes in the Kapp Starostin Formation of Spitsbergen, an island roughly 890 km north of the Norwegian mainland.

Fusulinids from the Topeka Limestone  (Upper Carboniferous of Kansas, USA) From Wikimedia Commons

Fusulinids from the Topeka Limestone (Upper Carboniferous of Kansas, USA) From Wikimedia Commons

The Kapp Starostin Formation contains cool-water boreal faunas that include abundant siliceous sponges, brachiopods, and bryozoans. The widespread and near-total loss of carbonates across the Boreal Realm also suggests a role for acidification in the crisis.  This extinction predates the end-Permian mass extinction, because a subsequent recovery of brachiopods and especially bivalves is seen in the Late Permian. This post-extinction fauna disappears 10 m below the top of the Kapp Starostin Formation and thus fails to survive until the end of the Permian (Bond et al., 2015). This is a true mass extinction because the new data suggest that about 50 per cent of all marine species died during the event.

Oceanic oxygen depletion represents a potent cause of extinction in marine settings, and is often linked with volcanic activity, warming, and transgression. However,  the role of anoxia in the wider Capitanian extinction scenario remains enigmatic. Volcanically induced effects are multiple and include acidification.

brachi

Brachiopods from the Kapp Starostin Formation (Image adapted from Bond et al., 2015)

Acidification affects the biogeochemical dynamics of calcium carbonate, organic carbon, nitrogen, and phosphorus in the ocean and interferes with a range of processes, including growth, calcification, development, reproduction and behaviour in a wide range of marine organisms like foraminifera, planktonic coccolithophores, pteropods and other molluscs,  echinoderms, corals, and coralline algae. Ocean acidification in the geological record, is often inferred from a decrease in the accumulation and preservation of CaCO3 in marine sediments, potentially indicated by an increased degree of fragmentation of foraminiferal shells. But, recently, a variety of trace-element and isotopic tools have become available to infer past seawater carbonate chemistry.

Undoubtedly, the proximity of the End Permian extinction, makes difficult to determine if these events are separate or are part of a the same event.

References:

David P.G. Bond, Paul B. Wignall, Michael M. Joachimski, Yadong Sun, Ivan Savov, Stephen E. Grasby, Benoit Beauchamp and Dierk P.G. Blomeier, 2015, An abrupt extinction in the Middle Permian (Capitanian) of the Boreal Realm (Spitsbergen) and its link to anoxia and acidification, Geological Society of America Bulletin, doi: 10.1130/B31216.1

Wignall, P.B., Bond, D.P.G., Kuwahara, K., Kakuwa, Y., Newton, R.J., and Poulton, S.W., 2010, An 80 million year oceanic redox history from Permian to Jurassic pelagic sediments of the Mino-Tamba terrane, SW Japan, and the origin of four mass extinctions: Global and Planetary Change, v. 71, p. 109–123, doi:10.1016/j.gloplacha .2010.01.022.

Wignall, P.B., Bond, D.P.G., Newton, R.J., Haas, J., Hips, K., Wang, W., Jiang, H.-S., Lai, X.-L., Sun, Y.-D., Altiner, D., Védrine, S., and Zajzon, N., 2012, The Capitanian (Middle Permian) mass extinction in western Tethys: A fossil, facies and δ13C study from Hungary and Hydra Island (Greece): Palaios, v. 27, p. 78–89, doi:10.2110/palo.2011.p11-058r.

Advertisements

The plant fossil record and the extinction events.

Odontopteris lingulata, seed fern from the Late  Late Pennsylvanian to Early Permian. (Image Credit: Taylor et al, 2009)

Odontopteris lingulata, seed fern from the Late Late Pennsylvanian to Early Permian. (Image Credit: Taylor et al, 2009)

Mass extinctions has shaped the global diversity of our planet several times during the geological ages. They were originally identified in the marine fossil record and have been interpreted as a result of catastrophic events or major environmental changes that occurred too rapidly for organisms to adapt.

In 1982, Jack Sepkoski and David M. Raup used a simple form of time series analysis at the rank of family to distinguish between background extinction levels and mass extinctions in marine faunas, and identified five major extinction events in Earth’s history: at the end of the Ordovician period, Frasnian (Late Devonian), Permian, Triassic and Cretaceous. But the plant fossil record reveals a different pattern of major taxonomic extinctions compared with marine organisms. The first of them took place at the Carboniferous-Permian transition, which is interpreted as result of the collapse of the tropical wetlands in Euramerica. The second mass extinction corresponds to the end-Permian event.

Glossopteris sp., seed ferns, Permian - Triassic - Houston Museum of Natural Science (From Wikimedia Commons)

Glossopteris sp., seed ferns, Permian – Triassic – Houston Museum of Natural Science (From Wikimedia Commons)

At the late Carboniferous the characteristic wetland families disappeared (e.g. Flemingitaceae, Diaphorodendraceae, Tedeleaceae, Urnatopteridaceae, Alethopteridaceae, Cyclopteridaceae, Neurodontopteridaceae). The downfall of rainforests probably reflects the complexity of the environmental changes that were taking place during the late Moscovian-early Sakmarian time interval (DiMichele et al., 2006, Sahney et al., 2010). This collapse probably drove the rapid diversification of Carboniferous tetrapods (amphibians and reptiles) in Euramerica (Sahney et al., 2010).

During the end-Permian Event, the woody gymnosperm vegetation (cordaitaleans and glossopterids) were replaced by spore-producing plants (mainly lycophytes) before the typical Mesozoic woody vegetation evolved. The palynological record suggests that wooded terrestrial ecosystems took four to five million years to reform stable ecosystems, while spore-producing lycopsids had an important ecological role in the post-extinction interval.

Schematic illustration comparing the three extinction events analized (From Vajda and Bercovici, 2014)

Schematic illustration comparing the three extinction events analized (From Vajda and Bercovici, 2014)

At the end-Triassic event,  the vegetation turnover in the Southern Hemisphere  consisted in the replacement to Alisporites (corystosperm)-dominated assemblage to a Classopollis (cheirolepidiacean)-dominated one.

The end-Cretaceous biotic crisis had a significant effect on marine and terrestrial faunas, and caused localized loss of species diversity in vegetation. Patagonia shows a reduction in diversity and relative abundance in almost all plant groups from the latest Maastrichtian to the Danian, although only a few true extinctions occurred (Barreda et al, 2013). The nature of vegetational change in the south polar region suggests that terrestrial ecosystems were already responding to relatively rapid climate change prior to the K–Pg catastrophe.

Two examples of grains pollen from the Lopez de Bertodano Formation: Podocarpidites sp. (left) and Nothofagidites asperus (right)

Two examples of grains pollen: Podocarpidites sp. (left) and Nothofagidites asperus (right)

A key factor for plant resilience is the time-scale: if the duration of the ecological disruption did not exceed that of the viability of seeds and spores, those plant taxa have the potential to recover (Traverse, 1988).

References:

Cascales-Miñana, B., and C. J. Cleal, 2014, The plant fossil record reflects just two great extinction events. Terra Nova. vol. 26, no. 3, pp. 195–200. DOI: 10.1111/ter.12086

Bambach, R.K., Knoll, A.H. and Wang, S.C., 2004. Origination, extinction, and mass depletions of marine diversity. Paleobiology, 30, 522–542.

Mayhew, Peter J.; Gareth B. Jenkins, Timothy G. Benton (January 7, 2008). “A long-term association between global temperature and biodiversity, origination and extinction in the fossil record”. Proceedings of the Royal Society B: Biological Sciences 275 (1630): 47–53.

Sahney, S., Benton, M.J. & Falcon-Lang, H.J. (2010). “Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica” (PDF). Geology 38 (12): 1079–1082. doi:10.1130/G31182.1.

 

The palynological record and the extinction events.

The main palynological provinces at the end of the Cretaceous (From Vajda and Bercovici, 2014)

The main palynological provinces at the end of the Cretaceous (From Vajda and Bercovici, 2014)

Pollen and other palynomorphs proved to be an extraordinary tool to palaeoenvironmental reconstruction. In 1921, Gunnar Erdtman, a Swedish botanist, was the first to suggest this application for fossil pollen study. Like spores, pollen grains reflects the ecology of their parent plants and their habitats and provide a continuous record of their evolutionary history. Pollen analysis involves the quantitative examination of spores and pollen at successive horizons through a core, specially in lake, marsh or delta sediments. The morphology of pollen grains is diverse. Gymnosperm pollen often is saccate (grains with two or three air sacs attached to the central body), while Angiosperm pollen shows more variation and covers a multitude of combinations of features: they could be  in groups of four (tetrads),  in pairs (dyads),  or single (monads). The individual grains can be inaperturate, or have one or more pores, or slit-like apertures or colpi (monocolpate, tricolpate).

Since the 1980s, many fossil pollen data sets were developed specifically to reconstruct past climate change.

Aquilapollenites quadricretaeus and Nothofagidites kaitangata

Aquilapollenites quadricretaeus and Nothofagidites kaitangata

 

The palynological record across the Cretaceous–Paleogene (K–Pg) boundary  is a unique global  marker that can be use as template to asses the causal mechanism behind other major extinction events in Earths history. Four major palynological provinces have been recognized based on distinctive angiosperm pollen and fern spores of restricted geographic and stratigraphic distribution. The Aquilapollenites Province had a northern circumpolar distribution that extended from Siberia, northern China, Japon and the western North America. The Normapolles Province occupied eastern North America,  Europe and western Asia. The Palmae Province occupied equatorial regions in the Late Cretacic and included SouthAmerica, Africa and India. Finally, the Notofagidites Province that extended across southern South America, Antartica, New Zeland and Australia.

During the Late Cretaceous the global climate change has been associated with episodes of outgassing from major volcanic events, orbital cyclicity and tectonism before ending with the cataclysm caused by a large bolide impact at Chicxulub, on the Yucatán Peninsula, Mexico. Although, during the middle Maastrichtian, there was a short-lived warming event related to an increase in atmospheric carbon dioxide from the first Deccan eruption phase, the global climate cooled during the latest Maastrichtian and across the K–Pg boundary (Wang et al., 2014; Brusatte et al., 2014). The variations in floral composition reflect these paleoclimatic changes.

Fern spike adapted from Bercovicci

Fern spike adapted from Bercovicci

Mainly angiosperms, disappear at the boundary, as evidenced the palynofloral records of North America and New Zealand. Patagonia shows a reduction in diversity and relative abundance in almost all plant groups from the latest Maastrichtian to the Danian, although only a few true extinctions occurred (Barreda et al, 2013).  The nature of vegetational change in the south polar region suggests that terrestrial ecosystems were already responding to relatively rapid climate change prior to the K–Pg catastrophe.

The earliest Paleocene vegetation shows an anomalous concentration of fern spores just above the level of palynological extinction. R. H. Tschudy, in 1984,  was the first to recognize this very distinctive pattern when he analyzed samples from the K/PG boundary and observed that just after the extinction event, the palynological assemblages were dominated by a high abundance of fern spores.

Schematic illustration comparing the three extinction events analized (From Vajda and Bercovici, 2014)

Schematic illustration comparing the three extinction events analized (From Vajda and Bercovici, 2014)

During the end-Permian Event, the woody gymnosperm vegetation (cordaitaleans and glossopterids) were replaced by spore-producing plants (mainly lycophytes) before the typical Mesozoic woody vegetation evolved. At the end-Triassic event,  the vegetation turnover in the Southern Hemisphere  consisted in the replacement to Alisporites (corystosperm)-dominated assemblage to a Classopollis (cheirolepidiacean)-dominated one.

Despite their difference, these three extinction events are consequences of dramatic environmental upheavals that generated comparable extinction patterns, and similar phases of vegetation recovery but at different temporal scales. First, all these events share a similar pattern of a short-term bloom of opportunistic “crisis” taxa proliferating in the devastated environment. Second, there’s a pulse in pioneer communities (spore spike). Third , a recovery in diversity including the evolution of new taxa. Furthermore, the longer the extreme environmental conditions last the greater is the extinction rate and the extinction patterns between autotrophs and heterotrophs, and between terrestrial and marine faunas become more similar (Vajda and Bercovici, 2014).

 

References:

Vivi Vajda & Antoine Bercovici (2014); The global vegetation pattern across the Cretaceous–Paleogene mass extinction interval: A template for other extinction events; Global and Planetary Change (advance online publication) Open Access DOI: 10.1016/j.gloplacha.2014.07.014, http://www.sciencedirect.com/science/article/pii/S0921818114001477

Vajda, V., Raine, J.I., 2003. Pollen and spores in marine Cretaceous/Tertiary boundary sediments at mid–Waipara River, North Canterbury, New Zealand. New Zealand Journal of Geology and Geophysics 46, 255–273

Wang, Y., Huang, C., Sun, B., Quan, C., Wu, J., Lin, Z., 2014. Paleo-CO2 variation trends and the Cretaceous greenhouse climate. Earth-Science Reviews 129, 136–147.

Vanessa C. Bowman, Jane E. Francis, Rosemary A. Askinb, James B. Riding, Graeme T. Swindles, Latest Cretaceous–earliest Paleogene vegetation and climate change at the high southern latitudes: palynological evidence fromSeymour Island, Antarctic Peninsula, Palaeogeography, Palaeoclimatology, Palaeoecology, 408. 26-47. DOI 10.1016/j.palaeo.2014.04.018

Barreda VD, Cúneo NR, Wilf P, Currano ED, Scasso RA, et al. (2012) Cretaceous/Paleogene Floral Turnover in Patagonia: Drop in Diversity, Low Extinction, and a Classopollis Spike. PLoS ONE 7(12): e52455. doi: 10.1371/journal.pone.0052455

Brusatte, S. L., Butler, R. J., Barrett, P. M., Carrano, M. T., Evans, D. C., Lloyd, G. T., Mannion, P. D., Norell, M. A., Peppe, D. J., Upchurch, P., and Williamson, T. E. In press. The extinction of the dinosaurs.Biological Reviews