scholarly journals Pteridophytes as primary colonisers after catastophic events through geological time and in recent history

2021 ◽  
Author(s):  
Barry A. Thomas ◽  
Christopher J. Cleal
Keyword(s):  
Recent History ◽  
Geological Time ◽  
Barren Land ◽  
Geological Record ◽  
Volcanic Islands ◽  
Extinction Events

AbstractPteridophytes reproduce by producing vast numbers of spores that may be dispersed over considerable distances, helping the plants colonise new areas. Being resistant to desiccation, fern spores can often survive for many years as spore banks in soil. After disturbance, such spores can germinate and subsequently colonise the area. These factors help pteridophytes to become primary colonisers on barren land, such as volcanic islands or land that has been devastated by some cataclysmic event. A further method of rapid colonisation is provided through the preservation and possible scattering of fragments of rhizomes in particular of horsetails. Similar rapid colonising by pteridophytes has been documented in the geological record following several major extinction events. These distinct, but short-lived, fern populations are recognisable by fern spikes in the microfossils. This paper brings together information on the reasons for pteridophyte success in colonising barren land, and examples taken from both the historic and geological records.

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.

Anthropocene: A Very Short Introduction

2018 ◽  
Author(s):  
Erle C. Ellis
Keyword(s):  
Climate Change ◽  
Mass Extinction ◽  
Scientific Community ◽  
Geological Time ◽  
Short Introduction ◽  
Geological Record ◽  
Species Invasions ◽  
Rapid Climate Change ◽  
The Relationship

Humanity’s impact on the planet has been profound. From fire, intensive hunting, and agriculture, it has accelerated into rapid climate change, widespread pollution, plastic accumulation, species invasions, and the mass extinction of species—changes that have left a permanent mark in the geological record of the rocks. Yet the proposal for a new unit of geological time—the Anthropocene Epoch—has raised debate far beyond the scientific community. The Anthropocene has emerged as a powerful new narrative of the relationship between humans and nature. Anthropocene: A Very Short Introduction draws on the work of geologists, geographers, environmental scientists, archaeologists, and humanities scholars to explain the science and wider implications of the Anthropocene.

Changing exhumation potential of (U)HP eclogite through geological time

2020 ◽  
Author(s):  
Richard Palin
Keyword(s):  
Continental Crust ◽  
Plate Tectonics ◽  
Global Network ◽  
Ultrahigh Pressure ◽  
Compositional Variation ◽  
Uhp Metamorphism ◽  
Geological Time ◽  
Geological Record ◽  
Mafic Intrusions ◽  
Archean Crust

<p>Ultrahigh-pressure (UHP) metamorphism is defined by achieving P–T conditions sufficient to transform quartz to coesite (~26–28 kbar at ~500–900 °C), which occurs at ~90-100 km depth within the Earth under lithostatic conditions. Thus, the occurrence of UHP metamorphism is often taken as being a diagnostic indicator of subduction having operated in the geological record, and hence plate tectonics. Yet, the oldest such coesite-bearing rocks belong to the Pan-African belt in northern Mali, and formed at 620 Ma, although there exist multiple lines of evidence to show that a global network of subduction had been operative on Earth for billions of years beforehand. Why, then, are these key geodynamic indicators missing from the majority of the rock record? Here, I show how secular cooling of the Earth's mantle since the Mesoarchean (c. 3.2 Ga) has affected the exhumation potential of UHP (and HP) eclogite through time due to time-dependent compositional variation of both oceanic and continental crust. Petrological modeling of density changes during metamorphism of Archean, Proterozoic, and Phanerozoic composite continental terranes shows that more mafic Archean crust reaches a point-of-no-return during transport into the mantle at shallower depths than less MgO-rich modern-day crust, regardless of whether this occurs via subduction of stagnant lid-like vertical 'drip' tectonics. Thus, while Alpine- and Himalayan-type (U)HP orogenic eclogites represented by metamorphosed mafic intrusions into continental crust may readily have formed during the Precambrian, they would have lacked the buoyancy required for exhumation and preservation in the geological record.</p>

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 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

1-D photochemical model predicts oxygen isotope anomalies in early Earth atmospheres

2020 ◽  
Author(s):  
Bethan Gregory ◽  
Mark Claire ◽  
Sarah Rugheimer
Keyword(s):  
Oxygen Isotope ◽  
Atmospheric Oxygen ◽  
Stratospheric Ozone ◽  
Atmospheric Composition ◽  
Geological Time ◽  
Geological Record ◽  
Oxygen Levels ◽  
Atmospheric Species ◽  
Photochemical Model ◽  
Modelling Studies

&lt;p&gt;Atmospheric oxygen and ozone over geological time have been constrained using various geochemical proxies and modelling studies, but ambiguity remains. Triple oxygen isotope measurements from Phanerozoic and Proterozoic rocks (e.g. Crockford et al., 2019) provide a direct record of ancient atmospheric composition, and as such are an exciting novel proxy. The only known source of mass-independent fractionation of oxygen isotopes (O-MIF) on Earth is in the formation of stratospheric ozone. A large positive O-MIF signal is imparted to ozone, while the larger reservoir of oxygen gains a much smaller negative O-MIF signal. These species interact with other gases in the atmosphere, and oxidised end products including nitrate, sulphate and perchlorate can persist in various geological archives such as ice, arid desert soil, and marine evaporites. As a result, the magnitude of the O-MIF signature detected in the geological record could be used to quantify levels of atmospheric ozone (and closely-related molecular oxygen) over certain time intervals. Here we develop a one-dimensional photochemical model to incorporate the three isotopes of oxygen, in order to trace oxygen isotope anomalies from stratospheric ozone through other atmospheric species, and into the geological record. This model, &amp;#8216;Atmos,&amp;#8217; has been calibrated over 40 years to provide credible estimates of atmospheric composition deviating from the modern. We use the model to show the lowest oxygen levels at which the anomaly can be produced and transferred, putting a potential lower limit on oxygen levels for parts of the Phanerozoic and mid-Proterozoic.&lt;/p&gt;&lt;p&gt;Reference:&lt;/p&gt;&lt;p&gt;Crockford, P.W., Kunzmann, M., Bekker, A., Hayles, J., Bao, H., Halverson, G.P., Peng, Y., Bui, T.H., Cox, G.M., Gibson, T.M. and W&amp;#246;rndle, S., 2019. Claypool continued: Extending the isotopic record of sedimentary sulfate.&amp;#160;Chemical Geology.&lt;/p&gt;

Ecologically diverse clades dominate the oceans via extinction resistance

Science ◽  
2020 ◽  
Vol 367 (6481) ◽  
pp. 1035-1038 ◽  
Author(s):  
Matthew L. Knope ◽  
Andrew M. Bush ◽  
Luke O. Frishkoff ◽  
Noel A. Heim ◽  
Jonathan L. Payne
Keyword(s):  
Taxonomic Diversity ◽  
Mass Extinctions ◽  
Taxonomic Richness ◽  
Geological Time ◽  
Evolutionary Time ◽  
Marine Animals ◽  
Ecological Differentiation ◽  
Marine Fauna ◽  
Extinction Events ◽  
The Relationship

Ecological differentiation is correlated with taxonomic diversity in many clades, and ecological divergence is often assumed to be a cause and/or consequence of high speciation rate. However, an analysis of 30,074 genera of living marine animals and 19,992 genera of fossil marine animals indicates that greater ecological differentiation in the modern oceans is actually associated with lower rates of origination over evolutionary time. Ecologically differentiated clades became taxonomically diverse over time because they were better buffered against extinction, particularly during mass extinctions, which primarily affected genus-rich, ecologically homogeneous clades. The relationship between ecological differentiation and taxonomic richness was weak early in the evolution of animals but has strengthened over geological time as successive extinction events reshaped the marine fauna.

scholarly journals Extinção e o registro fóssil

2007 ◽  
Vol 30 (1) ◽  
pp. 123-134
Author(s):  
Ibsen De Gusmão Câmara
Keyword(s):  
Biological Evolution ◽  
Geological Time ◽  
Evolutionary Processes ◽  
Paleontological Data ◽  
Extinction Events

The extinctions and their relationships with the biological evolution allow the changes in the biota patterns through the geological time. In this study is presented a synthesis of the extinction events registered in the paleontological data and their importance to the evolutionary processes.

Evidence for catastrophic organic changes in the geological record

2004 ◽  
Author(s):  
Tony Hallam
Keyword(s):  
Mass Extinction ◽  
Sedimentary Rocks ◽  
Significant Proportion ◽  
Natural World ◽  
European Population ◽  
Mass Extinctions ◽  
Geological Time ◽  
Geological Record ◽  
Coastal Cliffs ◽  
Definition Of

If asked what they understood by the word ‘catastrophe’, most people would probably agree that it was something big, bad, and sudden, and involved damage to organisms. In the natural world today, perhaps the most striking catastrophes result from major earthquakes, in which thousands of people can be killed within minutes. Going back through human history, we allow for greater stretches of time. Thus, in the middle of the fourteenth century, over a period of five years, an estimated one-third of the European population died directly as a result of catching the plague: the ‘Black Death’. By any reckoning this ranks as a catastrophe. It had a dramatic effect on European society for many years. When we extend our consideration to geological time, in which it is routine to deal with changes taking place over millions of years, events lasting only a few thousand years may be regarded as catastrophic if the contrast with the ‘background’ is sharp enough. Various definitions have been proposed for a mass extinction. A conveniently concise if imprecise one that I favour is that it is the extinction of a significant proportion of the world’s living animal and plant life (the biota) in a geologically insignificant period of time. The imprecision about the extent of an extinction can be dealt with fairly satisfactorily in particular instances by giving percentages of fossil families, genera, or species, but the imprecision about time is more difficult to deal with. An important question about mass extinctions is to assess how catastrophic they were, so we also require a definition of ‘catastrophe’ in this context. One thought-provoking attempt at such a definition is that a catastrophe is a perturbation of the biosphere that appears to be instantaneous when viewed at the level of detail that can be resolved in the geological record. At this point more needs to be said about the nature of the geological record. The material that geologists and palaeontologists deal with occurs in the layered successions of sedimentary rocks, mainly sandstones, shales, and limestones, that can clearly be observed in good rock exposures, either natural ones, as in coastal cliffs or mountains, or artificial ones, as in quarries or borehole cores.

Daughter of time

Paleobiology ◽  
1996 ◽  
Vol 22 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Andrew H. Knoll
Keyword(s):  
Morphological Change ◽  
Environmental History ◽  
Time Scale ◽  
Geological Time ◽  
Geological Time Scale ◽  
Geological Record ◽  
Evolutionary Mode

Truth, goes an old proverb, is the daughter of time. Fifty years ago, G. G. Simpson (1944) brought paleontology into the Neodarwinian fold, arguing that evolutionary tempo can be documented in the geological record and used to inform debate about evolutionary mode. Today, increasingly sophisticated paleontological investigations of rate—be it diversification, extinction, migration, morphological change, or divergence in macromolecular sequence—require calibration of the geological time scale with a precision far greater than Simpson could have anticipated. Expanding research on the relationships between environmental history and evolution also requires unprecedented resolution in correlation and geochronometry.

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