scholarly journals Meteorites that produce K-feldspar-rich ejecta blankets correspond to mass extinctions

2021 ◽  
pp. jgs2021-055
Author(s):  
M. J. Pankhurst ◽  
C. J. Stevenson ◽  
B. C. Coldwell
Keyword(s):  
Cloud Microphysics ◽  
Ice Nucleation ◽  
Mass Extinctions ◽  
Geological Time ◽  
Content Type ◽  
Meteorite Impacts ◽  
Cloud Dynamics ◽  
Supplementary Material ◽  
Extinction Events ◽  
Mass Extinction Events

Meteorite impacts load the atmosphere with dust and cover the Earth's surface with debris. They have long been debated as a trigger of mass extinctions through Earth's history. Impact winters generally last <100 years, whereas ejecta blankets persist for 103-105 years. Here we show that only meteorite impacts that emplaced ejecta blankets rich in K-feldspar (Kfs) correlate to Earth system crises (n=11, p<0.000005). Kfs is a powerful ice-nucleating aerosol yet is normally rare in atmospheric dust mineralogy. Ice nucleation plays an important role in cloud microphysics, which modulates global albedo. A conceptual model is proposed whereby the anomalous prevalence of Kfs is posited to have two key effects on cloud dynamics: 1) reducing the average albedo of mixed-phase cloud, which effected a hotter climate; 2) weakening of the cloud albedo feedback, which increased climate sensitivity. These mechanisms offer an explanation as to why this otherwise benign mineral is correlated so strongly with mass extinction events: every K-feldspar-rich ejecta blanket corresponds to a severe extinction episode over the past 600 Myr. This model may also explain why many kill mechanisms only variably correlate with extinction events through geological time: they coincide with these rare periods of climate destabilization by atmospheric Kfs.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5690646

Mass extinctions alter extinction and origination dynamics with respect to body size

2021 ◽  
Vol 288 (1960) ◽  
Author(s):  
Pedro M. Monarrez ◽  
Noel A. Heim ◽  
Jonathan L. Payne
Keyword(s):  
Body Size ◽  
Mass Extinction ◽  
Evolutionary Biology ◽  
Marine Animal ◽  
Mass Extinctions ◽  
Extinction Selectivity ◽  
Extinction Events ◽  
Mass Extinction Events ◽  
Marine Biosphere

Whether mass extinctions and their associated recoveries represent an intensification of background extinction and origination dynamics versus a separate macroevolutionary regime remains a central debate in evolutionary biology. The previous focus has been on extinction, but origination dynamics may be equally or more important for long-term evolutionary outcomes. The evolution of animal body size is an ideal process to test for differences in macroevolutionary regimes, as body size is easily determined, comparable across distantly related taxa and scales with organismal traits. Here, we test for shifts in selectivity between background intervals and the ‘Big Five’ mass extinction events using capture–mark–recapture models. Our body-size data cover 10 203 fossil marine animal genera spanning 10 Linnaean classes with occurrences ranging from Early Ordovician to Late Pleistocene (485–1 Ma). Most classes exhibit differences in both origination and extinction selectivity between background intervals and mass extinctions, with the direction of selectivity varying among classes and overall exhibiting stronger selectivity during origination after mass extinction than extinction during the mass extinction. Thus, not only do mass extinction events shift the marine biosphere into a new macroevolutionary regime, the dynamics of recovery from mass extinction also appear to play an underappreciated role in shaping the biosphere in their aftermath.

scholarly journals The origins of modern biodiversity on land

2010 ◽  
Vol 365 (1558) ◽  
pp. 3667-3679 ◽  
Author(s):  
Michael J. Benton
Keyword(s):  
Regional Scale ◽  
Global Scale ◽  
Scale Model ◽  
Time Range ◽  
Geological Time ◽  
New Methods ◽  
Evolution Of Life ◽  
History Of ◽  
Extinction Events ◽  
Mass Extinction Events

Comparative studies of large phylogenies of living and extinct groups have shown that most biodiversity arises from a small number of highly species-rich clades. To understand biodiversity, it is important to examine the history of these clades on geological time scales. This is part of a distinct ‘phylogenetic expansion’ view of macroevolution, and contrasts with the alternative, non-phylogenetic ‘equilibrium’ approach to the history of biodiversity. The latter viewpoint focuses on density-dependent models in which all life is described by a single global-scale model, and a case is made here that this approach may be less successful at representing the shape of the evolution of life than the phylogenetic expansion approach. The terrestrial fossil record is patchy, but is adequate for coarse-scale studies of groups such as vertebrates that possess fossilizable hard parts. New methods in phylogenetic analysis, morphometrics and the study of exceptional biotas allow new approaches. Models for diversity regulation through time range from the entirely biotic to the entirely physical, with many intermediates. Tetrapod diversity has risen as a result of the expansion of ecospace, rather than niche subdivision or regional-scale endemicity resulting from continental break-up. Tetrapod communities on land have been remarkably stable and have changed only when there was a revolution in floras (such as the demise of the Carboniferous coal forests, or the Cretaceous radiation of angiosperms) or following particularly severe mass extinction events, such as that at the end of the Permian.

The biology of mass extinction: a palaeontological view

1989 ◽  
Vol 325 (1228) ◽  
pp. 357-368 ◽  
Keyword(s):  
Mass Extinction ◽  
Large Scale ◽  
Individual Species ◽  
Ecological Groups ◽  
Mass Extinctions ◽  
Geological Time ◽  
Evolutionary Patterns ◽  
Data Set ◽  
High Species Richness ◽  
Extinction Events

Extinctions are not biologically random: certain taxa or functional/ecological groups are more extinction-prone than others. Analysis of molluscan survivorship patterns for the end-Cretaceous mass extinctions suggests that some traits that tend to confer extinction resistance during times of normal (‘background’) levels of extinction are ineffectual during mass extinction. For genera, high species-richness and possession of widespread individual species imparted extinction-resistance during background times but not during the mass extinction, when overall distribution of the genus was an important factor. Reanalysis of Hoffman’s (1986) data ( Neues Jb. Geol. Palaont. Abh. 172, 219) on European bivalves, and preliminary analysis of a new northern European data set, reveals a similar change in survivorship rules, as do data scattered among other taxa and extinction events. Thus taxa and adaptations can be lost not because they were poorly adapted by the standards of the background processes that constitute the bulk of geological time, but because they lacked - or were not linked to - the organismic, species-level or clade-level traits favoured under mass-extinction conditions. Mass extinctions can break the hegemony of species-rich, well-adapted clades and thereby permit radiation of taxa that had previously been minor faunal elements; no net increase in the adaptation of the biota need ensue. Although some large-scale evolutionary trends transcend mass extinctions, post-extinction evolutionary pathways are often channelled in directions not predictable from evolutionary patterns during background times.

scholarly journals The biogeographical imprint of mass extinctions

2018 ◽  
Vol 285 (1878) ◽  
pp. 20180232 ◽  
Author(s):  
Ádám T. Kocsis ◽  
Carl J. Reddin ◽  
Wolfgang Kiessling
Keyword(s):  
Mass Extinction ◽  
Marine Species ◽  
Mass Extinctions ◽  
Marine Life ◽  
Extinction Rates ◽  
Evolution Of Life ◽  
Severe Reduction ◽  
Permian Extinction ◽  
Extinction Events ◽  
Mass Extinction Events

Mass extinctions are defined by extinction rates significantly above background levels and have had substantial consequences for the evolution of life. Geographically selective extinctions, subsequent originations and species redistributions may have changed global biogeographical structure, but quantification of this change is lacking. In order to assess quantitatively the biogeographical impact of mass extinctions, we outline time-traceable bioregions for benthic marine species across the Phanerozoic using a compositional network. Mass extinction events are visually recognizable in the geographical depiction of bioregions. The end-Permian extinction stands out with a severe reduction of provinciality. Time series of biogeographical turnover represent a novel aspect of the analysis of mass extinctions, confirming concentration of changes in the geographical distribution of benthic marine life.

4. The great catastrophes

2019 ◽  
pp. 51-75
Author(s):  
Paul B. Wignall
Keyword(s):  
Big Five ◽  
Mass Extinction ◽  
Early Jurassic ◽  
Late Devonian ◽  
Mass Extinctions ◽  
Short Intervals ◽  
Extinction Rates ◽  
The World ◽  
Extinction Events ◽  
Mass Extinction Events

What is a mass extinction? Mass extinction events are geologically short intervals of time (always under a million years), marked by dramatic increases of extinction rates in a broad range of environments around the world. In essence they are global catastrophes that left no environment unaffected and that have fundamentally changed the trajectory of life. ‘The great catastrophes’ describes the big five mass extinctions—the end-Ordovician 445 million years ago, the Late Devonian 374 million years ago, the Permo-Triassic 252 million years ago, the end-Triassic 201 million years ago, and Cretaceous-Paleogene sixty-six million years ago—and thoughts on their likely causes, along with other important extinction events identified at the start of the Cambrian and in the Early Jurassic.

Climate modelling of mass-extinction events: a review

2009 ◽  
Vol 8 (3) ◽  
pp. 207-212 ◽  
Author(s):  
Georg Feulner
Keyword(s):  
Mass Extinction ◽  
Plate Tectonics ◽  
Large Scale ◽  
Volcanic Eruptions ◽  
Biological Species ◽  
Future Research ◽  
Climate Modelling ◽  
Mass Extinctions ◽  
Extinction Events ◽  
Mass Extinction Events

AbstractDespite tremendous interest in the topic and decades of research, the origins of the major losses of biodiversity in the history of life on Earth remain elusive. A variety of possible causes for these mass-extinction events have been investigated, including impacts of asteroids or comets, large-scale volcanic eruptions, effects from changes in the distribution of continents caused by plate tectonics, and biological factors, to name but a few. Many of these suggested drivers involve or indeed require changes of Earth's climate, which then affect the biosphere of our planet, causing a global reduction in the diversity of biological species. It can be argued, therefore, that a detailed understanding of these climatic variations and their effects on ecosystems are prerequisites for a solution to the enigma of biological extinctions. Apart from investigations of the paleoclimate data of the time periods of mass extinctions, climate-modelling experiments should be able to shed some light on these dramatic events. Somewhat surprisingly, however, only a few comprehensive modelling studies of the climate changes associated with extinction events have been undertaken. These studies will be reviewed in this paper. Furthermore, the role of modelling in extinction research in general and suggestions for future research are discussed.

Death Star or Coherent Catastrophism?

Impact! ◽  
1996 ◽  
Author(s):  
Gerrit L. Verschuur
Keyword(s):  
New York ◽  
Mass Extinction ◽  
Mass Extinctions ◽  
Life Threatening ◽  
Great Discovery ◽  
Regular Manner ◽  
Goddard Institute ◽  
Extinction Events ◽  
The University ◽  
Mass Extinction Events

Our instinct for survival drives us to learn as much as possible about what goes on around us. The better we understand nature, the better we will be able to predict its vagaries so as to avoid life-threatening situations. Unfortunately, nature is seldom so kind as to arrange for disasters to occur like clockwork, yet that does not dampen our enthusiasm when even a hint of periodicity in a complex phenomenon is spotted. This helps account for the furor that was created when a few paleontologists claimed that mass extinctions of species seemed to recur in a regular manner. A cycle, a periodicity, had been found! That implied that perhaps they might be able to predict nature’s next move. This is how I interpret the extraordinary public interest that was generated by the claims made around 1984 that the mass extinction phenomenon showed a roughly 30-million-year period (others said it was 26 million years). Almost immediately, several books appeared on the subject as well as many, many articles in the popular press and in science magazines. This activity marked the short life of the Death Star fiasco. Given our instinctual urge to look for order in the chaos of existence, the identification of a periodicity in mass-extinction events was a great discovery, if real. What was not highlighted by those who climbed aboard the bandwagon, however, was that the last peak in the pattern occurred about 13 million years ago. If impact-related mass extinction events were produced every 30 million years, there obviously was no cause for concern that we would be hit by a 10-kilometer object in the next 17 million years. Phew! I think that the suggestion that mass extinctions occurred on a regular cycle caused as much interest as it did because we all want to believe that there is no immediate danger to us. The Death Star fiasco began when David Raup and John Sepkowski of the University of Chicago published a report claiming that mass extinction events recurred about every 26 million years. They were followed by Michael Rampino and Richard Stothers of the Goddard Institute for Space Studies in New York who claimed that the period was more like 30 million years, at least during the last 250 million years.

Mass Extinctions as Statistical Phenomena: An Examination of the Evidence Using χ2 Tests and Bootstrapping

Paleobiology ◽  
1992 ◽  
Vol 18 (2) ◽  
pp. 148-160 ◽  
Author(s):  
Alan E. Hubbard ◽  
Norman L. Gilinsky
Keyword(s):  
Late Cretaceous ◽  
Mass Extinction ◽  
Late Ordovician ◽  
Statistical Evidence ◽  
Mass Extinctions ◽  
Late Permian ◽  
Turnover Rates ◽  
Historical Evidence ◽  
Extinction Events ◽  
Mass Extinction Events

Although much natural historical evidence has been adduced in support of the occurrence of several mass extinctions during the Phanerozoic, unambiguous statistical confirmation of the mass extinction phenomenon has remained elusive. Using bootstrapping techniques that have not previously been applied to the study of mass extinction, we have amassed strong or very strong statistical evidence for mass extinctions (see text for definitions) during the Late Ordovician, Late Permian, and Late Cretaceous. Bootstrapping therefore verifies three of the mass extinction events that were proposed by Raup and Sepkoski (1982). A small amount of bootstrapping evidence is also presented for mass extinctions in the Induan (Triassic) and Coniacean (Cretaceous) Stages, but high overall turnover rates (including high origination) in the Induan and uncertain estimates of the temporal duration of the Coniacean force us to conclude that the evidence is not compelling.We also present the results of more liberal X2 tests of the differences between expected and observed numbers of familial extinctions for stratigraphic stages. In addition to verifying the mass extinctions identified using bootstrapping, these analyses suggest that several stages that could not be verified as mass extinction stages using bootstrapping (including the last three in the Devonian, and the Norian Stage of the Triassic) should still be regarded as candidates for mass extinction. Further analysis will be required to test these stages in more detail.

scholarly journals Volcanic spherules condensed from supercritical fluids in the Payenia volcanic province, Argentina

2020 ◽  
Vol 178 (1) ◽  
pp. jgs2020-026
Author(s):  
Linda A. Kirstein ◽  
Silvestar Kanev ◽  
J. Godfrey Fitton ◽  
Stephen J. Turner ◽  
Keyword(s):  
Trace Element ◽  
Secondary Ion Mass Spectrometry ◽  
Trace Element Content ◽  
Volcanic Eruptions ◽  
Content Type ◽  
Lightning Strikes ◽  
Meteorite Impacts ◽  
High Temperature Processes ◽  
Supplementary Material ◽  
Sedimentary Carbonates

Spherules can be formed by high-temperature processes during volcanic eruptions, lightning strikes and meteorite impacts. Here we report four different types of spherules and spheroidal particles associated with tephra deposits from two separate volcanic fields in the southern Payenia province of Argentina. These silicate and carbonate spherules represent <0.01% of the sampled material, with individual spherules <200 µm in size. Thirty particles were imaged. Only the transparent spherules are smooth, perfect spheres; other morphologies include ellipsoids and aggregated dumbbells. The spheroids are either hollow or solid. Major element analyses show that the spherules and spheroids have silica-rich, Fe-rich, carbonate and basaltic compositions. Chemical analysis of the carbonate spheroids shows some variability in the trace element content between the cores and rims, suggesting element mobility and loss towards the margins. All the analysed carbonate spheroids have elevated Sr/Y, La/Y and La/Ce ratios outside the range for sedimentary carbonates. All four spherule types are considered to be volcanic in origin, with the excess CO2 required for the formation of the carbonate spherules potentially sourced from the basement lithologies. Based on the major and trace element analyses, we conclude that the silica-rich and carbonate spherules formed by instantaneous condensation from supercritical CO2-rich hydrous fluids saturated with dissolved silicates.Supplementary material: Appendix A, containing the full analytical dataset collected by electron probe microanalysis and secondary ion mass spectrometry, is available at https://doi.org/10.6084/m9.figshare.c.5108689

scholarly journals Mass Extinctions, Comet Impacts, and The Galaxy

1998 ◽  
Vol 11 (1) ◽  
pp. 246-251
Author(s):  
Michael R. Rampino ◽  
Richard B. Stothers
Keyword(s):  
Mass Extinction ◽  
Galactic Plane ◽  
Galactic Disk ◽  
Oort Cloud ◽  
Impact Craters ◽  
Statistical Analyses ◽  
Mass Extinctions ◽  
The Galaxy ◽  
Extinction Events ◽  
Mass Extinction Events

Abstract The hypothesis relating mass extinctions of life on Earth to impacts of comets whose flux is partly modulated by the dynamics of the Milky Way Galaxy contains a number of postulates that can be tested by geologic evidence and statistical analyses. In an increasing number of cases, geologic evidence for impact (widespread impact debris and/or large impact craters) is found at times of mass extinction events, and the record of dated impact craters has been found to show a significant correlation with mass extinctions. Statistical analyses suggest that mass extinction events exhibit a periodic component of about 26 to 30 Myr, and periodicities of 30± 0.5 Myr and 35 ±2 Myr have been extracted from sets of well-dated impact craters. The evidence is consistent with periodic or quasi-periodic showers of impactors, probably Oort Cloud comets, with an approximately 30-Myr cycle. The best explanation for these proposed quasi-periodic comet showers involves the Sun’s vertical oscillation through the galactic disk, which may have a similar cycle time between crossings of the galactic plane.

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