The Biography of the Earth

2021 ◽  
pp. 181-199
Author(s):  
Elisabeth Ervin-Blankenheim
Keyword(s):  
Snowball Earth ◽  
Burgess Shale ◽  
The Earth ◽  
Extinction Event ◽  
Extinction Events ◽  
Diversity Of Life ◽  
Rapid Shift

This chapter focuses on the first era of the Phanerozoic Eon (“visible life”), the Paleozoic Era, when life burgeoned after a rapid shift from a frozen setting during Snowball Earth times to dramatic warming related to greenhouse conditions. The chapter includes stories, such as that of the finding of the unique creatures of the Burgess Shale in Canada, that represent the diversity of life in the early part of the Paleozoic, the Cambrian Period. Several climatic shifts happened in the Paleozoic with resulting extinction events, the first occurring at the end of the Ordovician Period, the second at the end of the Devonian, and a third massive extinction at the end of the Permian Period. The latter was the largest extinction event ever recorded when 95 percent of all genera were killed as the supercontinent Pangea began to be split apart at the end of the Paleozoic.

scholarly journals Differential human impact on the survival of genetically distinct avian lineages

1999 ◽  
Vol 9 (2) ◽  
pp. 147-154 ◽  
Author(s):  
Austin L. Hughes
Keyword(s):  
Human Impact ◽  
Physical Environment ◽  
Mass Extinction ◽  
The Earth ◽  
Biotic Diversity ◽  
Extinction Event ◽  
Mass Extinction Event ◽  
Extinction Events ◽  
The Impact ◽  
Mass Extinction Events

SummaryAt the present time the earth is facing an anthropogenic (human-caused) mass extinction event that may eventually rival previous mass extinction events caused by drastic changes i n the physical environment; however, the impact of this event on the earth's biotic diversity remains difficult to predict. Patterns of extinction and endangerment in birds, one of the best known taxonomically among major groups of organisms, showed that the distribution of human impact has been non-uniform relative to phylogenetic relationships. Fifteen major avian lineages differed over 35-fold with respect to the frequency of historical extinction and over threefold with respect to frequency of current threat; and overall rates of both extinction and threat were significantly higher in non-passerine orders than in passerines. Moreover, among both passerines and non-passerines, the rate of historic extinction has been significantly higher for species in monotypic genera than for other species; and in passerines, the rate of current threat is significantly higher for species in monotypic genera than for other species. Thus, the anthropogenic extinction and threat to avian species has specifically targeted species that are phylogenetically and thus, presumably genetically, unique.

scholarly journals The Sixth Species Extinction Event by Humans

2015 ◽  
Vol 5 (1) ◽  
pp. 61-72
Author(s):  
Victor John Nazarevich
Keyword(s):  
Mass Extinction ◽  
Recent Literature ◽  
Theoretical Research ◽  
Future Research ◽  
The Earth ◽  
Unknown Species ◽  
Extinction Event ◽  
Extinction Events ◽  
The Impact ◽  
The Relationship

The number of species becoming extinct has drawn a significant deal of attention from scientists and non-scientists alike. This research reviews recent literature citing evidence for the impact humans have had on our planet and how our biological systems are affected in both known species of flora and fauna as well as unknown species of flora and fauna, the latter lacking documentation as well as sightings by humans. Theoretical research is derived from previous research investigating the impacts of humankind’s use of the land as well as population increases. Though there are many different definitions of what a mass extinction is and gradations of extinction intensity, a conservative approach is used to assess the seriousness of the current ongoing extinction crisis, setting the highest level of recognition for mass extinction, in extreme diversity loss associated with the Big Five extinction events (Barnosky, 2011). Understanding the relationship between extinction and functional diversity over time will be critical for making conservation work (Boyer & Jetz, 2014). If another mass extinction is allowed to progress, it would mean the end of biodiversity as we know it and would also mean that greater pressure would be placed on both humans and flora and fauna to survive in a world completely changed by the Anthropocene. Over the course of 8,000-10,000 years, humans grew in population and changed the landscape of the Earth (Foley, 2013). The research concludes that focus should be on preserving the environment and future research should be performed on the study of unknown species.

A new Late Silurian (Pridolian) naraoiid (Euarthropoda: Nektaspida) from the Bertie Formation of southern Ontario, Canada—delayed fallout from the Cambrian explosion

2004 ◽  
Vol 78 (6) ◽  
pp. 1138-1145 ◽  
Author(s):  
Jean-Bernard Caron ◽  
David M. Rudkin ◽  
Stuart Milliken
Keyword(s):  
Late Ordovician ◽  
Cambrian Explosion ◽  
Burgess Shale ◽  
Soft Bottom ◽  
Southern Ontario ◽  
Middle Cambrian ◽  
Holotype Specimen ◽  
Extinction Events ◽  
Lazarus Effect ◽  
Mass Extinction Events

The discovery of a new naraoiid nektaspid in the Upper Silurian (Pridolian) of southeastern Ontario significantly extends the range of this unusual group. Nektaspids are nonmineralized arthropods typical of Early and Middle Cambrian soft-bottom communities, but were thought to have become extinct in the Late Ordovician. The unique holotype specimen of Naraoia bertiensis n. sp. comes from a Konservat–Lagerstätte deposit renowned for its eurypterid fauna (the Williamsville Member of the Bertie Formation). Naraoia bertiensis lacks thoracic segments and is morphologically similar to Naraoia compacta from the Middle Cambrian Burgess Shale, save for the presence of a long ventral cephalic doublure and a subtly pointed posterior shield. To examine the phylogenetic relationships of the new naraoiid, we coded characters of the holotype specimen and of nine previously described nektaspids. The results confirm a sister taxon relationship between Naraoia compacta and Naraoia bertiensis and the monophyly of nektaspid forms lacking thoracic segments (family Naraoiidae). This latter group may have arisen from an ancestral segment-bearing form through heterochronic loss of thoracic segments early in the Cambrian. The disjunct occurrence of a naraoiid nektaspid in the Late Silurian resembles the reappearance of other “Lazarus taxa” that were thought to have been eliminated during mass extinction events. The naraoiid lineage survived the Late Ordovician biotic crisis, but in this case the “Lazarus effect” seems likely to be taphonomic in origin.

New U–Pb constraints identify the end-Guadalupian and possibly end-Lopingian extinction events conceivably preserved in the passive margin of North America: implication for regional tectonics

2016 ◽  
Vol 155 (1) ◽  
pp. 119-131 ◽  
Author(s):  
V. I. DAVYDOV ◽  
J. L. CROWLEY ◽  
M. D. SCHMITZ ◽  
W. S. SNYDER
Keyword(s):  
North America ◽  
Volcanic Ash ◽  
New Age ◽  
Passive Margin ◽  
Cool Water ◽  
Extinction Event ◽  
Stratigraphic Position ◽  
Extinction Events ◽  
Phosphoria Formation ◽  
Regional Tectonics

AbstractThe discovery and dating of a volcanic ash bed within the upper Phosphoria Formation in SE Idaho, USA, is reported. The ash occurs 11 m below the top of the phosphatic Meade Peak Member and yielded a 206Pb/238U date of 260.57 ± 0.07 / 0.14 / 0.31 Ma, i.e. latest Capitanian, Guadalupian. The stratigraphic position of this ash near the top of the Meade Peak phosphatic Member of Phosphoria Formation indicates plausible completeness of the sedimentation within the Guadalupian–Lopingian and probably at the Permo-Triassic (P-T) transitions. The new radiometric age reveals that the regional biostratigraphy and palaeontology of Phosphoria and Park City formations requires serious reconsideration, particularly in cool water conodonts, bryozoans and brachiopods. The new age proposes that the Guadalupian–Lopingian boundary (GLB) coincides with the Meade Peak – Rex contact and consequently with the end-Guadalupian extinction event. The lack of a major unconformity at the P-T transition suggests that the effects of the Sonoma orogeny were not as extensive as has been assumed.

The Biography of the Earth

2021 ◽  
pp. 163-180
Author(s):  
Elisabeth Ervin-Blankenheim
Keyword(s):  
Early Life ◽  
Plate Tectonics ◽  
Life Forms ◽  
Snowball Earth ◽  
The Moon ◽  
Geologic Time ◽  
Earth Systems ◽  
Organic Life ◽  
The Earth ◽  
Geologic Record

The way the planet has changed through geologic time, and life on it, the account of the Earth, is the topic of this and the next three chapters, starting in this chapter with the Precambrian Supereon. The overarching principles of geologic time, plate tectonics, and evolution worked dynamically to create the biography of the planet. This chapter traces back to the recesses of the geologic record and early Earth, from its birth and the formation of the Moon through seven-eighths of its existence, a huge span of time. Early life forms emerged during this supereon in the Archean Eon and had a profound influence on other Earth systems. Life interacted and changed the chemistry of the atmosphere through photosynthesis, so much so that the changes are thought to have sent planetary systems over an edge into multiple “Snowball Earth” episodes when most of the planet froze over. In addition to the beginning of organic life and climate, the emergence and configuration of the continents during the Precambrian are covered. Events of this supereon set the stage for the burgeoning of life forms in the next eon, the Phanerozoic.

The Biography of the Earth

2021 ◽  
pp. 200-213
Author(s):  
Elisabeth Ervin-Blankenheim
Keyword(s):  
Small Mammals ◽  
Ecological Niche ◽  
Late Jurassic ◽  
Big Bang ◽  
Ecological Niches ◽  
Asteroid Impact ◽  
The Earth ◽  
The One ◽  
Extinction Events ◽  
The Universe

The story of the Phanerozoic Eon continues in this chapter with the Mesozoic Era. The first period in the Mesozoic, the Triassic, was bookended by two extinction events, the one at the beginning, discussed in the prior chapter at the end of the Permian Period, the Great Dying, and then another at the end of the period, related to the further breakup of Pangea. Dinosaurs evolved and diversified during the Mesozoic to occupy nearly each and every ecological niche on the planet, with large dinosaurs and small dinosaurs, ones that flew, those that ate vegetation, and those that preyed upon the herbivores—making this time a dino-dominated age. In the late Jurassic Period, small mammals, many of them insectivores, were starting to become prevalent. The era ended with a “big bang” of a different type than is theorized as the start of the universe—with the Chicxulub asteroid impact 66 million years ago that ended the lives of most of the dinosaurs, the non-avian lines, and opened up new ecological niches for the next “masters of the universe,” the mammals.

scholarly journals Cyberpunk Redux: Dérives in the Rich Sight of Post-Anthropocentric Visuality

Arts ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 38 ◽  
Author(s):  
Frenchy Lunning
Keyword(s):  
Advanced Technology ◽  
Department Stores ◽  
Late 19Th Century ◽  
Blade Runner ◽  
The Earth ◽  
Primary Object ◽  
The World ◽  
The Rich ◽  
Century Development

Our future effects on the earth, in light of the Anthropocene, are all dire expressions of a depleted world left in piles of detritus and toxic ruin—including the diminished human as an assemblage of impoverished existence, yet adumbrating that handicapped existence with an ersatz advanced technology. In the cyberpunk films, these expressions are primarily visual expressions—whether through written prose thick with densely dark adjectives describing the world of cyberpunk, or more widely known, the comic books and films of cyberpunk, whose representations have become classically understood as SF canon. The new films of the cyberpunk redux however, represent an evolution in cyberpunk visuality. Despite these debatable issues around this term, it will provide this paper with its primary object of visuality, that of the “rich sight”, a further term that arose from the allure created in the late 19th century development of department stores that innovated the display of the goods laid out in a spectacular view, presenting the shopper with a fantasy of wealth and fetishized objects which excited shoppers to purchase, but more paradoxically, creating the desire to see a fantasy that was at the same time also a reality. This particular and enframed view—so deeply embedded and beloved in our commodity-obsessed culture—is what I suggest so profoundly typifies the initial cyberpunk postmodern representation in the Blade Runner films, and its continuing popularity in the early part of the 21st century. Both films are influenced by Ridley Scott’s initial vision of the cinematic cyberpunk universe and organized as sequential narratives. Consequently, they serve as excellent examples of the evolution of this visual spectacular.

Geographic variation in turnover and recovery from the Late Ordovician mass extinction

Paleobiology ◽  
2007 ◽  
Vol 33 (3) ◽  
pp. 435-454 ◽  
Author(s):  
Andrew Z. Krug ◽  
Mark E. Patzkowsky
Keyword(s):  
Mass Extinction ◽  
Late Ordovician ◽  
Mass Extinctions ◽  
Climatic Fluctuations ◽  
Extinction Rates ◽  
Large Size ◽  
Extinction Event ◽  
Global Extinction ◽  
Rate Of Recovery ◽  
Extinction Events

AbstractUnderstanding what drives global diversity requires knowledge of the processes that control diversity and turnover at a variety of geographic and temporal scales. This is of particular importance in the study of mass extinctions, which have disproportionate effects on the global ecosystem and have been shown to vary geographically in extinction magnitude and rate of recovery.Here, we analyze regional diversity and turnover patterns for the paleocontinents of Laurentia, Baltica, and Avalonia spanning the Late Ordovician mass extinction and Early Silurian recovery. Using a database of genus occurrences for inarticulate and articulate brachiopods, bivalves, anthozoans, and trilobites, we show that sampling-standardized diversity trends differ for the three regions. Diversity rebounded to pre-extinction levels within 5 Myr in the paleocontinent of Laurentia, compared with 15 Myr or longer for Baltica and Avalonia. This increased rate of recovery in Laurentia was due to both lower Late Ordovician extinction rates and higher Early Silurian origination rates relative to the other continents. Using brachiopod data, we dissected the Rhuddanian recovery into genus origination and invasion. This analysis revealed that standing diversity in the Rhuddanian consisted of a higher proportion of invading taxa in Laurentia than in either Baltica or Avalonia. Removing invading genera from diversity counts caused Rhuddanian diversity to fall in Laurentia. However, Laurentian diversity still rebounded to pre-extinction levels within 10 Myr of the extinction event, indicating that genus origination rates were also higher in Laurentia than in either Baltica or Avalonia. Though brachiopod diversity in Laurentia was lower than in the higher-latitude continents prior to the extinction, increased immigration and genus origination rates made it the most diverse continent following the extinction. Higher rates of origination in Laurentia may be explained by its large size, paleogeographic location, and vast epicontinental seas. It is possible that the tropical position of Laurentia buffered it somewhat from the intense climatic fluctuations associated with the extinction event, reducing extinction intensities and allowing for a more rapid rebound in this region. Hypotheses explaining the increased levels of invasion into Laurentia remain largely untested and require further scrutiny. Nevertheless, the Late Ordovician mass extinction joins the Late Permian and end-Cretaceous as global extinction events displaying an underlying spatial complexity.

Subtropical clouds stabilize near-Snowball Earth states

2020 ◽  
Author(s):  
Christoph Braun ◽  
Aiko Voigt ◽  
Johannes Hörner ◽  
Joaquim G. Pinto
Keyword(s):  
Sea Ice ◽  
General Circulation ◽  
General Circulation Models ◽  
Snowball Earth ◽  
Radiative Effects ◽  
Albedo Feedback ◽  
The Earth ◽  
Cloud Radiative Effects ◽  
Planetary Albedo ◽  
The Impact

<p>Atmospheric general circulation models developed for the Earth system include comprehensive parameterizations of clouds. Applying them to exoplanet atmospheres provides an opportunity to advance understanding of clouds, atmosphere dynamics, and their coupling in the context of planetary climate dynamics and habitability.</p><p>Here, we study a deep-time extreme climate of Earth as an example of the cold limit of the habitable zone. Geological evidence indicates near-global ice cover during the Neoproterozoic (1000 – 541 Million years ago) associated with considerable hysteresis of atmospheric CO<sub>2</sub>. The Snowball Earth hypothesis provides a straightforward interpretation of Neoproterozoic proxies based on a runaway of the sea-ice albedo feedback. However, the Snowball Earth hypothesis relies on the existence of local habitats to explain the survival of photosynthetic marine species on an entirely ice-covered planet. The Jormungand hypothesis may resolve this issue by considering a weakening of the sea-ice albedo feedback by exposure of dark bare sea ice when sea ice enters the subtropics. This potentially allows the Earth system to stabilize in a climate state - the Jormungand state - with near-global ice cover. Around the equator, a narrow strip of ocean remains ice-free, where life would have easily survived during the pan-glaciations.</p><p>The weakening of the sea-ice albedo feedback is based on the change of the meridional structure of planetary albedo with a moving sea-ice edge. While previous work focused on the contribution of surface albedo to planetary albedo, we here focus on the impact of subtropical and tropical cloudiness on planetary albedo. Enhanced cloudiness generally weakens the sea-ice albedo feedback and thus decreases the climate sensitivity of the Jormungand state, i.e. it stabilizes the Jormungand state. We analyze the impact of cloudiness on the stability of the Jormungand state in the general circulation models CAM3 and ICON-AES with idealized aquaplanet setups. While CAM3 shows significant CO<sub>2</sub>-hysteresis of the Jormungand state, ICON-AES exhibits no stable Jormungand state. Consistently, CAM3 exhibits stronger cloudiness than ICON-AES, especially in the subtropics. An analysis with a one-dimensional energy balance model shows that the Jormungand hysteresis strongly depends on the sensitivity of the planetary albedo to an advance of sea ice into the subtropics. Accordingly, we demonstrate that the absence of cloud-radiative effects within vertical columns in the subtropics drastically decreases the Jormungand hysteresis in CAM3.</p><p>Overall, the magnitude of the Jormungand hysteresis is tightly linked to the representation of cloud-radiative effects in general circulation models. Our results highlight the important role of uncertainties associated with cloud-radiative effects for climate feedbacks on planet Earth in the context of extreme climates, such as they have occurred in Earth’s deep past or might be found on Earth-like planets. In consequence, this also stresses the need and challenges of accounting for adequate cloud modeling for planetary climates.</p>

scholarly journals Identifying the most surprising victims of mass extinction events: an example using Late Ordovician brachiopods

2017 ◽  
Vol 13 (9) ◽  
pp. 20170400 ◽  
Author(s):  
Seth Finnegan ◽  
Christian M. Ø. Rasmussen ◽  
David A. T. Harper
Keyword(s):  
Deep Water ◽  
Mass Extinction ◽  
Late Ordovician ◽  
Extinction Rate ◽  
Simple Method ◽  
Training Models ◽  
Extinction Event ◽  
Extinction Events ◽  
Mass Extinction Events

Mass extinction events are recognized by increases in extinction rate and magnitude and, often, by changes in the selectivity of extinction. When considering the selective fingerprint of a particular event, not all taxon extinctions are equally informative: some would be expected even under a ‘background’ selectivity regime, whereas others would not and thus require special explanation. When evaluating possible drivers for the extinction event, the latter group is of particular interest. Here, we introduce a simple method for identifying these most surprising victims of extinction events by training models on background extinction intervals and using these models to make per-taxon assessments of ‘expected’ risk during the extinction interval. As an example, we examine brachiopod genus extinctions during the Late Ordovician Mass Extinction and show that extinction of genera in the deep-water ‘ Foliomena fauna’ was particularly unexpected given preceding Late Ordovician extinction patterns.

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