Abundance and extinction in Ordovician–Silurian brachiopods, Cincinnati Arch, Ohio and Kentucky

Paleobiology ◽  
2012 ◽  
Vol 38 (2) ◽  
pp. 278-291 ◽  
Author(s):  
Andrew Zaffos ◽  
Steven M. Holland
Keyword(s):  
Spatial Scale ◽  
Mass Extinction ◽  
Fossil Record ◽  
Late Ordovician ◽  
Complex Relationship ◽  
Third Order ◽  
Evolutionary Advantage ◽  
Basic Hypothesis ◽  
Extinction Events ◽  
The Relationship

A basic hypothesis in extinction theory predicts that more abundant taxa have an evolutionary advantage over less abundant taxa, which should manifest as increased survivorship during major extinction events and longer fossil-record durations. Despite this, various paleontologic studies have found conflicting patterns, indicating a more complex relationship between abundance and extinction in the geologic past. This study tests the relationship between abundance and extinction among brachiopod genera within seven third-order depositional sequences spanning the Late Ordovician to Early Silurian (Katian–Aeronian) of the Cincinnati Arch.Contrary to predictions, abundance is not positively correlated with duration in this study. Abundance and duration range from strongly negatively correlated to uncorrelated depending on the spatial scale of analysis and the geologic intervals included, but correlations never indicate that abundance is an evolutionary advantage. In contrast, abundance was an advantageous trait prior to the Ordovician/Silurian extinction, and brachiopods with higher abundances were more likely to survive the event than less abundant brachiopods. While this result is in keeping with common models of extinction, it has not been observed previously at a mass extinction boundary. This may be further evidence that the Ordovician/Silurian extinction was not accompanied by a shift in the macroevolutionary selectivity regime.

Estimating the number of pulses in a mass extinction

Paleobiology ◽  
2018 ◽  
Vol 44 (2) ◽  
pp. 199-218 ◽  
Author(s):  
Steve C. Wang ◽  
Ling Zhong
Keyword(s):  
Mass Extinction ◽  
Fossil Record ◽  
Nearest Neighbor ◽  
Hypothesis Test ◽  
Information Criterion ◽  
Data Set ◽  
Recovery Potential ◽  
Step Algorithm ◽  
Extinction Events ◽  
Fossil Preservation

AbstractThe Signor-Lipps effect states that even a sudden mass extinction will invariably appear gradual in the fossil record, due to incomplete fossil preservation. Most previous work on the Signor–Lipps effect has focused on testing whether taxa in a mass extinction went extinct simultaneously or gradually. However, many authors have proposed scenarios in which taxa went extinct in distinct pulses. Little methodology has been developed for quantifying characteristics of such pulsed extinction events. Here we introduce a method for estimating the number of pulses in a mass extinction, based on the positions of fossil occurrences in a stratigraphic section. Rather than using a hypothesis test and assuming simultaneous extinction as the default, we reframe the question by asking what number of pulses best explains the observed fossil record.Using a two-step algorithm, we are able to estimate not just the number of extinction pulses but also a confidence level or posterior probability for each possible number of pulses. In the first step, we find the maximum likelihood estimate for each possible number of pulses. In the second step, we calculate the Akaike information criterion and Bayesian information criterion weights for each possible number of pulses, and then apply ak-nearest neighbor classifier to these weights. This method gives us a vector of confidence levels for the number of extinction pulses—for instance, we might be 80% confident that there was a single extinction pulse, 15% confident that there were two pulses, and 5% confident that there were three pulses. Equivalently, we can state that we are 95% confident that the number of extinction pulses is one or two. Using simulation studies, we show that the method performs well in a variety of situations, although it has difficulty in the case of decreasing fossil recovery potential, and it is most effective for small numbers of pulses unless the sample size is large. We demonstrate the method using a data set of Late Cretaceous ammonites.

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.

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.

Principles of Thermal Ecology: Temperature, Energy, and Life

2017 ◽  
Author(s):  
Andrew Clarke
Keyword(s):  
Physical Environment ◽  
Fossil Record ◽  
Final Section ◽  
Thermal Ecology ◽  
Complex Relationship ◽  
Physical Mechanisms ◽  
Influence Of Temperature On ◽  
Rigorous Framework ◽  
Effects Of Temperature ◽  
The Relationship

Temperature affects everything. It influences all aspects of the physical environment and governs any process that involves a flow of energy, setting boundaries on what an organism can or cannot do. This novel textbook explores the key principles behind the complex relationship between organisms and temperature, namely the science of thermal ecology. It starts providing a rigorous framework for understanding the nature of temperature and the flow of energy in and out of the organism, before describing the influence of temperature on what organisms can do, and how fast they can do it. Central to this is the relationship between temperature and metabolism, which then forms the basis for an exploration of the effects of temperature on growth and size. Two chapters cover first endothermy (including how this expensive lifestyle might have evolved), and then when and how this is suspended in torpor and hibernation. With these fundamental principles covered, the book’s final section explores thermal ecology itself, incorporating the important extra dimension of interactions with other organisms. After an examination of the relationship between temperature, energy and diversity, an entire chapter is devoted to the crucially important subject of the nature of climate change and how organisms are responding to this. Throughout the book, emphasis is placed on the need for an understanding of the underlying physical mechanisms, and the important insights that can be gained from the historical and fossil record.

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.

Mass extinction events and the plant fossil record

2007 ◽  
Vol 22 (10) ◽  
pp. 548-557 ◽  
Author(s):  
Jennifer C. McElwain ◽  
Surangi W. Punyasena
Keyword(s):  
Mass Extinction ◽  
Fossil Record ◽  
Plant Fossil ◽  
Extinction Events ◽  
Mass Extinction Events

Evidence for extinction selectivity throughout the marine invertebrate fossil record

Paleobiology ◽  
2009 ◽  
Vol 35 (4) ◽  
pp. 553-564 ◽  
Author(s):  
G. Alex Janevski ◽  
Tomasz K. Baumiller
Keyword(s):  
Species Richness ◽  
Mass Extinction ◽  
Fossil Record ◽  
Marine Invertebrate ◽  
Species Level ◽  
Geologic History ◽  
Extinction Selectivity ◽  
Extinction Events ◽  
Open Question ◽  
Mass Extinction Events

The fossil record has been used to show that in some geologic intervals certain traits of taxa may increase their survivability, and therefore that the risk of extinction is not randomly distributed among taxa. It has also been suggested that traits that buffer against extinction in background times do not confer the same resistance during mass extinction events. An open question is whether at any time in geologic history extinction probabilities were randomly distributed among taxa. Here we use a method for detecting random extinction to demonstrate that during both background and mass extinction times, extinction of marine invertebrate genera has been nonrandom with respect to species richness categories of genera. A possible cause for this nonrandom extinction is selective clustering of extinctions in genera consisting of species which possess extinction-biasing traits. Other potential causes considered here include geographic selectivity, increased extinction susceptibility for species in species-rich genera, or biases related to taxonomic practice and/or sampling heterogeneity. An important theoretical result is that extinction selectivity at the species level cannot be smoothly extrapolated upward to genera; the appearance of random genus extinction with respect to species richness of genera results when extinction has been highly selective at the species level.

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.

Rates of extinction in marine invertebrates: further comparison between background and mass extinctions

Paleobiology ◽  
1990 ◽  
Vol 16 (1) ◽  
pp. 22-24 ◽  
Author(s):  
J. Francis Thackeray
Keyword(s):  
Mass Extinction ◽  
Marine Invertebrates ◽  
Marine Invertebrate ◽  
Statistical Analyses ◽  
Logarithmic Scale ◽  
Mass Extinctions ◽  
Low Background ◽  
Background Levels ◽  
Extinction Events ◽  
The Relationship

Prominent extinction “events” have been recognized from statistical analyses of marine invertebrate genera represented in Mesozoic and Cenozoic assemblages, contrasting with relatively low “background” extinction intensities measured in terms of a “percentage extinction” index. On a logarithmic scale, the slope of the relationship between time and extinction intensity for background extinctions is shown to be parallel to the slope obtained for most extinction events, characterized by intensities 100.35 above prevailing background levels. Although extinction intensities are variable, this study suggests that the magnitude of the factor(s) primarily associated with most mass extinctions in a 260-m.y. period (N = 9) need not necessarily have been very different from one event to another, an exception being the mass extinction at the end of the Cretaceous.

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