Geochemical Records Reveal Protracted and Differential Marine Redox Change Associated With Late Ordovician Climate and Mass Extinctions

Perturbations to the global carbon cycle as recorded in the isotopic compositions of marine deposits have been commonly associated with major shifts in the climate and/or biologic activity, including mass extinctions. The Late Ordovician Guttenberg isotopic carbon excursion (GICE) is a large, globally correlative positive shift (∼3‰) in the carbon isotopic composition of marine carbonates (δ13Ccarb), but its driving mechanism(s) remains ambiguous. This is in large part due to uncertain correlations among Late Ordovician records, as well as complex and poorly constrained temporal relationships of abundant K-bentonite (altered volcanic ash) marker beds deposited in this time interval. Here, we provide new, high-precision U-Pb zircon geochronology by chemical-abrasion−isotope-dilution−thermal ionization mass spectrometry for K-bentonites bounding the GICE in the North American Midcontinent, including robust 206Pb/238U ages (reported with 2σ analytical uncertainty) for two important regional markers: the Deicke (453.35 ± 0.10 Ma) and Millbrig (453.36 ± 0.14 Ma) K-bentonites. The new data from these K-bentonites directly constrain the duration of the GICE to less than 400 k.y. at two well-studied locations in eastern Missouri, United States. The abruptness of the GICE precludes relatively gradual tectonic mechanisms as possible drivers of the excursion and suggests more rapid environmental drivers, such as changes in eustatic sea level associated with pre-Hirnantian glacial activity.

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

Paleobiology ◽

10.1666/06039.1 ◽

2007 ◽

Vol 33 (3) ◽

pp. 435-454 ◽

Cited By ~ 25

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.

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Do all mass extinctions represent an ecological crisis? Evidence from the Late Ordovician

Geological Journal ◽

10.1002/gj.880 ◽

2001 ◽

Vol 36 (3-4) ◽

pp. 329-340 ◽

Cited By ~ 70

Author(s):

P. J. Brenchley ◽

J. D. Marshall ◽

C. J. Underwood

Keyword(s):

Late Ordovician ◽

Ecological Crisis ◽

Mass Extinctions

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

Paleobiology ◽

10.1017/s0094837300013944 ◽

1992 ◽

Vol 18 (2) ◽

pp. 148-160 ◽

Cited By ~ 16

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.

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

Paleobiology ◽

10.1017/s0094837300026385 ◽

2007 ◽

Vol 33 (3) ◽

pp. 435-454 ◽

Cited By ~ 14

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.

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Late Ordovician Glaciation Initiated by Early Land Plant Evolution and Punctuated by Greenhouse Mass Extinctions

The Journal of Geology ◽

10.1086/683663 ◽

2015 ◽

Vol 123 (6) ◽

pp. 509-538 ◽

Cited By ~ 7

Author(s):

Gregory J. Retallack

Keyword(s):

Land Plant ◽

Late Ordovician ◽

Plant Evolution ◽

Mass Extinctions ◽

Early Land Plant ◽

Land Plant Evolution ◽

Early Land

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Did a gamma-ray burst initiate the late Ordovician mass extinction?

International Journal of Astrobiology ◽

10.1017/s1473550404001910 ◽

2004 ◽

Vol 3 (1) ◽

pp. 55-61 ◽

Cited By ~ 109

Author(s):

A.L. Melott ◽

B.S. Lieberman ◽

C.M. Laird ◽

L.D. Martin ◽

M.V. Medvedev ◽

...

Keyword(s):

Mass Extinction ◽

Gamma Ray ◽

Late Ordovician ◽

Mass Extinctions ◽

Solar Ultraviolet Radiation ◽

Observable Universe ◽

The Earth ◽

Global Cooling ◽

History Of ◽

Solar Ultraviolet

Gamma-ray bursts (GRBs) produce a flux of radiation detectable across the observable Universe. A GRB within our own galaxy could do considerable damage to the Earth's biosphere; rate estimates suggest that a dangerously near GRB should occur on average two or more times per billion years. At least five times in the history of life, the Earth has experienced mass extinctions that eliminated a large percentage of the biota. Many possible causes have been documented, and GRBs may also have contributed. The late Ordovician mass extinction approximately 440 million years ago may be at least partly the result of a GRB. A special feature of GRBs in terms of terrestrial effects is a nearly impulsive energy input of the order of 10 s. Due to expected severe depletion of the ozone layer, intense solar ultraviolet radiation would result from a nearby GRB, and some of the patterns of extinction and survivorship at this time may be attributable to elevated levels of UV radiation reaching the Earth. In addition, a GRB could trigger the global cooling which occurs at the end of the Ordovician period that follows an interval of relatively warm climate. Intense rapid cooling and glaciation at that time, previously identified as the probable cause of this mass extinction, may have resulted from a GRB.

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Effects of mass extinction and recovery dynamics on long-term evolutionary trends: a morphological study of Strophomenida (Brachiopoda) across the Late Ordovician mass extinction

Paleobiology ◽

10.1017/pab.2018.24 ◽

2018 ◽

Vol 44 (4) ◽

pp. 603-619 ◽

Cited By ~ 4

Author(s):

Judith A. Sclafani ◽

Curtis R. Congreve ◽

Andrew Z. Krug ◽

Mark E. Patzkowsky

Keyword(s):

Mass Extinction ◽

Phylogenetic Trees ◽

Late Ordovician ◽

Ecological Communities ◽

Evolutionary Trends ◽

Mass Extinctions ◽

Principal Coordinates Analysis ◽

Principal Coordinates ◽

Recovery Dynamics

AbstractMass extinctions affect the history of life by decimating existing diversity and ecological structure and creating new evolutionary and ecological pathways. Both the loss of diversity during these events and the rebound in diversity following extinction had a profound effect on Phanerozoic evolutionary trends. Phylogenetic trees can be used to robustly assess the evolutionary implications of extinction and origination.We examine both extinction and origination during the Late Ordovician mass extinction. This mass extinction was the second largest in terms of taxonomic loss but did not appear to radically alter Paleozoic marine assemblages. We focus on the brachiopod order Strophomenida, whose evolutionary relationships have been recently revised, to explore the disconnect between the processes that drive taxonomic loss and those that restructure ecological communities.A possible explanation for this disconnect is if extinction and origination were random with respect to morphology. We define morphospace using principal coordinates analysis (PCO) of character data from 61 Ordovician–Devonian taxa and their 45 ancestral nodes, defined by a most parsimonious reconstruction in Mesquite. A bootstrap of the centroid of PCO values indicates that genera were randomly removed from morphospace by the Late Ordovician mass extinction, and new Silurian genera were clustered within a smaller previously unoccupied region of morphospace. Diversification remained morphologically constrained throughout the Silurian and into the Devonian. This suggests that the recovery from the Late Ordovician mass extinction resulted in a long-term shift in strophomenide evolution. More broadly, recovery intervals may hold clues to understanding the evolutionary impact of mass extinctions.

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