A Permian lagerstätte from Antarctica.

 

Vertebraria solid-stele and polyarch roots colonised by fungal spores (From Slater et al., 2014)

Vertebraria solid-stele and polyarch roots colonised by fungal spores (From Slater et al., 2014)

A lagerstätte (German for ‘storage place’) is a site exhibiting an extraordinary preservation of life forms from a particular era. The term was originally coined by Adolf Seilacher in 1970. One of the most notable  is Burgess Shale in the Canadian Rockies of British Columbia. The site, discovered by Charles Walcott in 1909, highlight one of the most critical events in evolution: the Cambrian Explosion (540 million to 525 million years ago). The factors that can create such fossil bonanzas are: rapid burial (obrution), stagnation (eutrophic anoxia), fecal pollution (septic anoxia), bacterial sealing (microbial death masks), brine pickling (salinization), mineral infiltration (permineralization and nodule formation by authigenic cementation), incomplete combustion (charcoalification), desiccation (mummification) and freezing. The preservation of decay-resistant lignin of wood and cuticle of plant leaves  is widespread, but exceptional preservation also extends to tissues.

The Toploje Member chert of the Prince Charles Mountains preserves the permineralised remains of a terrestrial ecosystem before the biotic decline that began in the Capitanian and continued through the Lopingian until the Permo-Triassic transition (Slater et al., 2014). During the late Palaeozoic and early Mesozoic, Antarctica occupied a central position within Gondwana and played a key role in floristic interchange between the various peripheral regions of the supercontinent.

permian

Singhisporites hystrix, a megaspore with ornamented surface.

The fossil micro-organism assemblage includes a broad range of fungal hyphae and reproductive structures. The macrofloral diversity in the silicified peats is relatively low and dominated by the constituent dispersed organs of arborescent glossopterid and cordaitalean gymnosperms.  The fossil palynological assemblage includes a broad range of dispersed bisaccate, monosaccate, monosulcate and polyplicate pollen. The roots (Vertebraria), stems (Australoxylon) and leaves (Glossopteris) of the arborescent glossopterid exhibited feeding traces caused by arthropods, but the identification is  difficult since plant and arthropod cuticles look similar in thin section. Tetrapods are currently unknown from Permian strata of the Prince Charles Mountains as either body fossils or ichnofossils (McLoughlin et al., 1997, Slater et al., 2014).

Times of exceptional fossil preservation are coincident with mass extinctions, oceanic anoxic events, carbon isotope anomalies, spikes of high atmospheric CO2, and transient warm-wet paleoclimates in arid lands (Retallack 2011). The current greenhouse crisis delivers several factors that can promote exceptional fossil preservation, such as eutrophic and septic anoxia, microbial sealing, and permineralization.

References:

Benton, M.J., Newell, A.J., (2013), Impacts of global warming on Permo-Triassic terrestrial ecosystems. Gondwana Research.

Rees, P.M., (2002). Land plant diversity and the end-Permian mass extinction. Geology 30, 827–830.

Retallack, G., (2011), Exceptional fossil preservation during CO2 greenhouse crises?, Palaeogeography, Palaeoclimatology, Palaeoecology 307: 59–74.

Slater, B.J., et al., (2014), A high-latitude Gondwanan lagerstätte: The Permian permineralised peat biota of the Prince Charles Mountains, Antarctica, Gondwana Research. http://dx.doi.org/10.1016/j.gr.2014.01.004

Seilacher, A., (1970) “Begriff und Bedeutung der Fossil-Lagerstätten: Neues Jahrbuch fur Geologie und Paläontologie“. Monatshefte (in German) 1970: 34–39.

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Ocean acidification and the end-Permian mass extinction

 

Permian Seafloor Photograph by University of Michigan Exhibit Museum of Natural History.

Permian Seafloor
Photograph by University of Michigan Exhibit Museum of Natural History.

About one third of the carbon dioxide released by anthropogenic activity is absorbed by the oceans. But the CO2 uptake lowers the pH and alters the chemical balance of the oceans. This phenomenon is called ocean acidification, and is occurring at a rate faster than at any time in the last 300 million years (Gillings, 2014; Hönisch et al. 2012). 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 planktonic coccolithophores, foraminifera, pteropods and other molluscs,  echinoderms, corals, and coralline algae. Rapid additions of carbon dioxide during extreme events in Earth history, including the end-Permian mass extinction (252 million years ago) and the Paleocene-Eocene Thermal Maximum (PETM, 56 million years ago) may have driven surface waters to undersaturation.

Flow chart summarizing proposed cause-and-effect relationships during the end-Permian extinction (From Bond and Wignall, 2014)

Flow chart summarizing proposed cause-and-effect relationships during the end-Permian extinction (From Bond and Wignall, 2014)

The end-Permian extinction is the most severe biotic crisis in the fossil record, with as much as 95% of the marine animal species and a similarly high proportion of terrestrial plants and animals going extinct . This great crisis occurred about 252 million years ago (Ma) during an episode of global warming.  The cause or causes of the Permian extinction remain a mystery but new data indicates that the extinction had a duration of 60,000 years and may be linked to massive volcanic eruptions from the Siberian Traps. The same study found evidence that 10,000 years before the die-off, the ocean experienced a pulse of light carbon that most likely led to a spike of carbon dioxide in the atmosphere. Volcanism and coal burning also contribute gases to the atmosphere, such as Cl, F, and CH3Cl from coal combustion, that suppress ozone formation.

Image that shows field work in the United Arab Emirates. Credit: D. Astratti

Image that shows field work in the United Arab Emirates. Credit: D. Astratti

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. The boron isotope composition of carbonate samples obtained from a shallow-marine platform section at Wadi Bih on the Musandam Peninsula, United Arab Emirates, allowed to reconstruct seawater pH values and atmospheric pCO2 concentrations and obtain for the very first time, direct evidence of ocean acidification in the Permo-Triassic boundary. The evidence indicates that the first phase of extinction was coincident with a slow injection of carbon into the atmosphere, and ocean pH remained stable. During the second extinction pulse, however, a rapid and large injection of carbon caused an abrupt acidification event that drove the preferential loss of heavily calcified marine biota (Clarkson et al, 2015).

The increasing evidence that the end-Permian mass extinction was precipitated by rapid release of CO2 into Earth’s atmosphere is a valuable reminder for an immediate action on global carbon emission reductions.

 

References:

Clarkson MO, Kasemann SA, Wood RA, Lenton TM, Daines SJ, Richoz S, Ohnemueller F, Meixner A, Poulton SW, Tipper ET. Ocean acidification and the Permo-Triassic mass extinction. Science, 2015 DOI: 10.1126/science.aaa0193

Feng, Q., Algeo, T.J., Evolution of oceanic redox conditions during the Permo-Triassic transition: Evidence from deepwater radiolarian facies, Earth-Sci. Rev. (2014), http://dx.doi.org/10.1016/j.earscirev.2013.12.003

Hönisch, A. Ridgwell, D. N. Schmidt, E. Thomas, S. J. Gibbs, A. Sluijs, R. Zeebe, L. Kump, R. C. Martindale, S. E. Greene, W. Kiessling, J. Ries, J. C. Zachos, D. L. Royer, S. Barker, T. M. Marchitto Jr., R. Moyer, C. Pelejero, P. Ziveri, G. L. Foster, B. Williams, The geological record of ocean acidification. Science 335, 1058–1063 (2012).

Kump, L.R., T.J. Bralower, and A. Ridgwell (2009)  Ocean acidification in deep time. Oceanography 22(4):94–107, http://dx.doi.org/10.5670/oceanog.2009.100

Seth D. Burgess, Samuel Bowring, and Shu-zhong Shen, High-precision timeline for Earth’s most severe extinction, PNAS 2014, doi:10.1073/pnas.1317692111

 

Poirot and the mysterious case of the Permian extinction.

 

Siberian flood-basalt flows in Putorana, Taymyr Peninsula.(From Earth science: Lethal volcanism, Paul B. Wignall, 2011,  Nature 477, 285–286 )

Siberian flood-basalt flows in Putorana, Taymyr Peninsula.(From Earth science: Lethal volcanism, Paul B. Wignall, 2011, Nature 477, 285–286 )

On the winter of 1934 during travel across Europe on board of the Orient Express Hercules Poirot, the famous Belgian detective faced the most intriguing and defiance case of his career: the murder of Mr. Ratchett. During the investigation Poirot reveals the real identity of the victim and the horrible crime that he committed in the past. Poirot also discovered that everyone on the coach had motives to kill Ratchett. With the help of Mr. Bouc, an acquaintance of Poirot and director of the company operating the Orient Express, Poirot arrives at two conclusions: first, a stranger boarded the train and murdered Ratchett; second, that all 13 people on the coach were complicit in the murder.

When Agatha Christie created this complicated plot in 1934, she never heard about the most perfect and yet mysterious death scene of all time: the Permo-Triassic extinction event. But that wasn’t her fault. Despite Cuvier’s  notable remarks about massive periodic catastrophes or “revolutions” found in the fossil record, scientists only started to focus on the massive extinctions in the middle of the twentieth century.

Western Pangea during the Late Permian (From Scotesse, 2010)

Western Pangea during the Late Permian (From Scotesse, 2010)

The end-Permian extinction is the most severe biotic crisis in the fossil record. This great crisis occurred about 252 million years ago (Ma) during an episode of global warming. The extinction had a duration of 60,000 years. For years there was a great debate about the cause or multiple causes of this catastrophic event, so Douglas Erwin, in 1993,  used Poirot’s second hypothesis to explain the Permo-Triassic event.  He called this hypothesis “The Murder on the Orient Express Model”. But what forces converged to wipe out almost 97% of species on Earth?

At the Permian Period, almost all land masses were reunited in one single supercontinent: Pangea, which stretched from the northern to the southern pole. Due to the formation of this supercontinent, the habitable marine area was reduced and the climate showed severe extremes with great seasonal fluctuations between wet and dry conditions. Ten thousand years before the extinction event there was a spike of carbon dioxide in the atmosphere, that  led to ocean acidification and warmer temperatures.

Gallery_Image_11433

The permian triassic boundary at Meishan, China (Photo: Shuzhong Shen)

Massive volcanic eruptions in Siberia covered more than 2 millions of km 2 with lava flows, releasing more carbon in the atmosphere and high amounts of fluorine and chlorine increasing the climatic inestability. Warmer oceans, possibly had melted frozen methane located in marine sediments which pushed the global temperatures to higher levels.

Recently, a study analyzing rock samples from Meishan, China, pointed a new suspect: a microbe, called Methanosarcina. This microbe is related to a superexponential burst in the carbon cycle and a spike the availability of nickel. But, some scientist remain sceptical about when Methanosarcina actually evolved.

We are close to find the answer to the Great Dying, but thus far, the best possible explanation for this severe extinction still is: THEY ALL DID IT!

References:

Agatha Christie, Murder on the Orient Express (1934), Collins Crime Club.

Douglas H. Erwin, Extinction: How Life on Earth Nearly Ended 250 Million Years Ago, Princeton University Press, 2006

Seth D. Burgess, Samuel Bowring, and Shu-zhong Shen, High-precision timeline for Earth’s most severe extinction, PNAS 2014, doi:10.1073/pnas.1317692111

Daniel H. Rothman, Gregory P. Fournier, Katherine L. French, Eric J. Alm, Edward A. Boyle, Changqun Cao, and Roger E. Summons (2014) “Methanogenic burst in the end-Permian carbon cycle,” PNAS doi: 10.1073/pnas.1318106111

Brief history of the Ocean Acidification through time.

Corals one of the most vulnerable creatures in the ocean. Photo Credit: Katharina Fabricius/Australian Institute of Marine Science

Corals one of the most vulnerable creatures in the ocean. Photo Credit: Katharina Fabricius/Australian Institute of Marine Science

At the end of the nineteenth century Svante Arrhenius and Thomas Chamberlain were among the few scientists that explored the relationship between carbon dioxide concentrations in the atmosphere and global warming. About one third of the carbon dioxide released by anthropogenic activity is absorbed by the oceans. But the CO2 uptake lowers the pH and alters the chemical balance of the oceans. This phenomenon is called ocean acidification, and is occurring at a rate faster than at any time in the last 300 million years (Gillings, 2014; Hönisch et al. 2012). Acidification affects the biogeochemical dynamics of calcium carbonate, organic carbon, nitrogen, and phosphorus in the ocean as well as the seawater chemical will directly impact in a wide range of marine organisms that build shells from calcium carbonate, like planktonic coccolithophores and pteropods and other molluscs,  echinoderms, corals, and coralline algae.

The geologic record of ocean acidification provide valuable insights into potential biotic impacts and time scales of recovery.  Rapid additions of carbon dioxide during extreme events in Earth history, including the end-Permian mass extinction (252 million years ago) and the Paleocene-Eocene Thermal Maximum (PETM, 56 million years ago) may have driven surface waters to undersaturation. But, there’s  no perfect analog for our present crisis, because we are living in an “ice house” that started 34 million years ago  with the growth of ice sheets on Antarctica, and this cases corresponded to events initiated during “hot house” (greenhouse) intervals of Earth history.

Coccolithophores exposed to differing levels of acidity. Adapted by Macmillan Publishers Ltd: Nature Publishing Group, Riebesell, U., et al., Nature 407, 2000.

Coccolithophores exposed to differing levels of acidity. Adapted by Macmillan Publishers Ltd: Nature Publishing Group, Riebesell, U., et al., Nature 407, 2000.

The end-Permian extinction is the most severe biotic crisis in the fossil record, with as much as 95% of the marine animal species and a similarly high proportion of terrestrial plants and animals going extinct . This great crisis ocurred about 252 million years ago (Ma) during an episode of global warming. The cause or causes of the Permian extinction remain a mystery but new data indicates that the extinction had a duration of 60,000 years and may be linked to massive volcanic eruptions from the Siberian Traps. The same study found evidence that 10,000 years before the die-off, the ocean experienced a pulse of light carbon that most likely led to a spike of carbon dioxide in the atmosphere. This could have led to ocean acidification, warmer water temperatures that effectively killed marine life.

The early Aptian Oceanic Anoxic Event (120 million years ago) was an interval of dramatic change in climate and ocean circulation. The cause of this event was the eruption of the Ontong Java Plateau in the western Pacific, wich led to a major increase in atmospheric pCO2 and ocean acidification. This event was characterized by the occurrence of organic-carbon-rich sediments on a global basis along with evidence for warming and dramatic change in nanoplankton assemblages. Several oceanic anoxic events (OAEs) are documented in Cretaceous strata in the Canadian Western Interior Sea.

major changes in plankton assembledge

The Paleocene-Eocene Thermal Maximum (PETM; 55.8 million years ago) was a short-lived (~ 200,000 years) global warming event. Temperatures increased by 5-9°C. It was marked by the largest deep-sea mass extinction among calcareous benthic foraminifera in the last 93 million years. Similarly, planktonic foraminifer communities at low and high latitudes show reductions in diversity. The PETM is also associated with dramatic changes among the calcareous plankton,characterized by the appearance of transient nanoplankton taxa of heavily calcified forms of Rhomboaster spp., Discoaster araneus, and D. anartios as well as Coccolithus bownii, a more delicate form

The current rate of the anthropogenic carbon input  is probably greater than during the PETM, causing a more severe decline in ocean pH and saturation state. Also the biotic consequences of the PETM were fairly minor, while the current rate of species extinction is already 100–1000 times higher than would be considered natural. This underlines the urgency for immediate action on global carbon emission reductions.

References:

Kump, L.R., T.J. Bralower, and A. Ridgwell. 2009. Ocean acidification in deep time. Oceanography 22(4):94–107, http://dx.doi.org/10.5670/oceanog.2009.100

Kroeker, K. J. et al. Impacts of ocean acidification on marine organisms: quantifying sensitivities and interaction with warming. Glob. Change Biol. 19, 1884–1896 (2013).

Payne JL, Turchyn AV, Paytan A, Depaolo DJ, Lehrmann DJ, Yu M, Wei J, Calcium isotope constraints on the end-Permian mass extinction, Proc Natl Acad Sci U S A. 2010 May 11;107(19):8543-8. doi: 10.1073/pnas.0914065107. Epub 2010 Apr 26.

Zeebe RE and Zachos JC. 2013 Long-term legacy ofmassive carbon input to the Earth system: Anthropocene versus Eocene. Phil Trans R Soc A 371: 20120006.http://dx.doi.org/10.1098/rsta.2012.0006.

Daniel H. Rothman, Gregory P. Fournier, Katherine L. French, Eric J. Alm, Edward A. Boyle, Changqun Cao, and Roger E. Summons (2014) “Methanogenic burst in the end-Permian carbon cycle,” PNAS doi: 10.1073/pnas.1318106111

Michael R Gillings, Elizabeth L Hagan-Lawson, The cost of living in the Anthropocene,  Earth Perspectives 2014, DOI 10.1186/2194-6434-1-2