Extinction from a paleontological perspective

Extinction of widespread species is common in evolutionary time (millions of years) but rare in ecological time (hundreds or thousands of years). In the fossil record, there appears to be a smooth continuum between background and mass extinction; and the clustering of extinctions at mass extinctions cannot be explained by the chance coincidence of independent events. Although some extinction is selective, much is apparently random in that survivors have no recognizable superiority over victims. Extinction certainly plays an important role in evolution, but whether it is constructive or destructive has not yet been determined.

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Large-body impact: the least unlikely cause of pulsed extinction

The Paleontological Society Special Publications ◽

10.1017/s2475262200008005 ◽

1992 ◽

Vol 6 ◽

pp. 240-240

Author(s):

David M. Raup

Keyword(s):

Short Interval ◽

Large Body ◽

Temporal Distribution ◽

Radiometric Dating ◽

Mass Extinctions ◽

Widespread Species ◽

Chance Coincidence ◽

Asteroid Impact ◽

The Past ◽

Independent Events

In the past year, a strong consensus in the geological community has developed in favor of comet or asteroid impact as the ultimate cause of the K-T mass extinction, although many paleontologists remain doubtful. The discovery of tektites and craters with argon-argon ages matching the K-T boundary has finally removed the “smoking gun” problem. It is important, therefore, to evaluate large-body impact as a possible cause of other Phanerozoic extinctions, and to do so as carefully as possible before enthusiasm for the K-T success overwhelms objectivity in this research area.Approximately 60% of all species extinctions in the Phanerozoic occurred in “pulsed” extinctions, defined as ecologically and geographically pervasive episodes in which the number of species going extinct in a geologically short interval far exceeds any reasonable estimate based on chance coincidence of independent events. In addition to the well-known mass extinctions, pulsed extinctions often mark system, series, and stage boundaries, and probably some zonal boundaries.To be plausible, any proposed cause of pulsed extinctions must be (1) geographically pervasive (regional or global), (2) effective in diverse habitats, and (3) relatively quick-acting (to inhibit survival of species by migration or adaptation). The stresses causing the extinctions must be sufficiently severe and rare to be beyond the reach of natural selection, so that species do not have prior opportunity to evolve defenses.These requirements severely limit the possibilities to phenomena that occur on time scales of one million to tens of millions of years, far longer than the tens or hundreds of years available for study by traditional actualistic approaches. In view of the Phanerozoic record, it is not surprising that the earth has not experienced a pulsed extinction in historic times (excluding human influences). This suggests that extinction is one case where the present is a not the key to the past, and a full exploration of the problem will require a substantial re-ordering of thinking.Furthermore, because pulsed extinctions involve geographically widespread species (as well as restricted taxa), and because extinction of widespread species may be qualitatively different from that of local endemics, the common extrapolation from studies of extinction in local populations is risky.Of the many phenomena suggested as causes of pulsed extinction, large-body impact is the one that most nearly satisfies the requirements, and is therefore the least unlikely of the candidates. Temporal distribution is especially critical. Currently accepted flux estimates for comet and asteroid impacts are in the appropriate frequency range to explain the extinction record, but testing the hypothesis will depend on better radiometric dating of the 100+ craters and other confirmed impact events.

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Diversification events and the effects of mass extinctions on Crocodyliformes evolutionary history

Royal Society Open Science ◽

10.1098/rsos.140385 ◽

2015 ◽

Vol 2 (5) ◽

pp. 140385 ◽

Cited By ~ 43

Author(s):

Mario Bronzati ◽

Felipe C. Montefeltro ◽

Max C. Langer

Keyword(s):

Mass Extinction ◽

Fossil Record ◽

Evolutionary History ◽

Continuous Process ◽

Mass Extinctions ◽

Terrestrial Habitats ◽

History Of ◽

The Rich ◽

A Minor ◽

Diversification Event

The rich fossil record of Crocodyliformes shows a much greater diversity in the past than today in terms of morphological disparity and occupation of niches. We conducted topology-based analyses seeking diversification shifts along the evolutionary history of the group. Our results support previous studies, indicating an initial radiation of the group following the Triassic/Jurassic mass extinction, here assumed to be related to the diversification of terrestrial protosuchians, marine thalattosuchians and semi-aquatic lineages within Neosuchia. During the Cretaceous, notosuchians embodied a second diversification event in terrestrial habitats and eusuchian lineages started diversifying before the end of the Mesozoic. Our results also support previous arguments for a minor impact of the Cretaceous/Palaeogene mass extinction on the evolutionary history of the group. This argument is not only based on the information from the fossil record, which shows basal groups surviving the mass extinction and the decline of other Mesozoic lineages before the event, but also by the diversification event encompassing only the alligatoroids in the earliest period after the extinction. Our results also indicate that, instead of a continuous process through time, Crocodyliformes diversification was patchy, with events restricted to specific subgroups in particular environments and time intervals.

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Synchronology, taxonomy and reality

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1989.0088 ◽

1989 ◽

Vol 325 (1228) ◽

pp. 263-277 ◽

Cited By ~ 5

Keyword(s):

Mass Extinction ◽

Fossil Record ◽

Secondary Data ◽

Primary Data ◽

Mass Extinctions

Geochronometry is only of limited help in establishing the timing of evolutionary events. Biostratigraphy and the establishment of a global standard stratigraphic scale are essential. These must be handled sensibly. Suggested periodicity of extinctions is dismissed. So called ‘mass extinctions’ are assessed by reference to the Ordovician-Silurian, Frasnian-Famennian and Cretaceous-Tertiary examples. Too ready use of the term ‘mass extinction’ tends to over-dramatize the patterns truly obtainable from the fossil record. It is easier to play with secondary data than to collect primary data.

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Confidence intervals for the duration of a mass extinction

Paleobiology ◽

10.1666/11016.1 ◽

2012 ◽

Vol 38 (2) ◽

pp. 265-277 ◽

Cited By ~ 11

Author(s):

Steve C. Wang ◽

Aaron E. Zimmerman ◽

Brendan S. McVeigh ◽

Philip J. Everson ◽

Heidi Wong

Keyword(s):

Confidence Interval ◽

Confidence Intervals ◽

Late Cretaceous ◽

Mass Extinction ◽

Fossil Record ◽

Mass Extinctions ◽

Late Permian ◽

Stratigraphic Section ◽

Stratigraphic Thickness ◽

Seymour Island

A key question in studies of mass extinctions is whether the extinction was a sudden or gradual event. This question may be addressed by examining the locations of fossil occurrences in a stratigraphic section. However, the fossil record can be consistent with both sudden and gradual extinctions. Rather than being limited to rejecting or not rejecting a particular scenario, ideally we should estimate therangeof extinction scenarios that is consistent with the fossil record. In other words, rather than testing the simplified distinction of “sudden versus gradual,” we should be asking, “How gradual?”In this paper we answer the question “How gradual could the extinction have been?” by developing a confidence interval for the duration of a mass extinction. We define the duration of the extinction as the time or stratigraphic thickness between the first and last taxon to go extinct, which we denote by Δ. For example, we would like to be able to say with 90% confidence that the extinction took place over a duration of 0.3 to 1.1 million years, or 24 to 57 meters of stratigraphic thickness. Our method does not deny the possibility of a truly simultaneous extinction; rather, in this framework, a simultaneous extinction is one whose value of Δ is equal to zero years or meters.We present an algorithm to derive such estimates and show that it produces valid confidence intervals. We illustrate its use with data from Late Permian ostracodes from Meishan, China, and Late Cretaceous ammonites from Seymour Island, Antarctica.

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Are Insects Heading Toward Their First Mass Extinction? Distinguishing Turnover From Crises in Their Fossil Record

Annals of the Entomological Society of America ◽

10.1093/aesa/saaa042 ◽

2020 ◽

Author(s):

Sandra R Schachat ◽

Conrad C Labandeira

Keyword(s):

Mass Extinction ◽

Fossil Record ◽

Taxonomic Diversity ◽

Insect Diversity ◽

Mass Extinctions ◽

Sudden Loss ◽

Faunal Turnover ◽

Sixth Mass Extinction ◽

Extinction Event ◽

Permian Extinction

Abstract Time and again, over hundreds of millions of years, environmental disturbances have caused mass extinctions of animals ranging from reptiles to corals. The anthropogenic loss of species diversity happening now is often discussed as the ‘sixth mass extinction’ in light of the ‘Big Five’ mass extinctions in the fossil record. But insects, whose taxonomic diversity now appears to be threatened by human activity, have a unique extinction history. Prehistoric losses of insect diversity at the levels of order and family appear to have been driven by competition among insect lineages, with biotic replacement ensuring minimal net losses in taxonomic diversity. The end-Permian extinction, the ‘mother of mass extinctions’ in the seas, was more of a faunal turnover than a mass extinction for insects. Insects’ current biotic crisis has been measured in terms of the loss of abundance and biomass (rather than the loss of species, genera, or families) and these are essentially impossible to measure in the fossil record. However, should the ongoing loss of insect abundance and biomass cause the demise of many insect families, the current extinction event may well be the first sudden loss of higher-level insect diversity in our planet’s history. This is not insects’ sixth mass extinction—in fact, it may become their first.

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Numerical experiments with model monophyletic and paraphyletic taxa

Paleobiology ◽

10.1017/s0094837300015852 ◽

1993 ◽

Vol 19 (2) ◽

pp. 168-184 ◽

Cited By ~ 76

Author(s):

J. John Sepkoski ◽

David C. Kendrick

Keyword(s):

Monte Carlo ◽

Monte Carlo Simulations ◽

Mass Extinction ◽

Fossil Record ◽

Numerical Experiments ◽

Mass Extinctions ◽

Diversity Patterns ◽

Extinction Rates ◽

Low Levels

The problem of how accurately paraphyletic taxa versus monophyletic (i.e., holophyletic) groups (clades) capture underlying species patterns of diversity and extinction is explored with Monte Carlo simulations. Phylogenies are modeled as stochastic trees. Paraphyletic taxa are defined in an arbitrary manner by randomly choosing progenitors and clustering all descendants not belonging to other taxa. These taxa are then examined to determine which are clades, and the remaining paraphyletic groups are dissected to discover monophyletic subgroups. Comparisons of diversity patterns and extinction rates between modeled taxa and lineages indicate that paraphyletic groups can adequately capture lineage information under a variety of conditions of diversification and mass extinction. This suggests that these groups constitute more than mere “taxonomic noise” in this context. But, strictly monophyletic groups perform somewhat better, especially with regard to mass extinctions. However, when low levels of paleontologic sampling are simulated, the veracity of clades deteriorates, especially with respect to diversity, and modeled paraphyletic taxa often capture more information about underlying lineages. Thus, for studies of diversity and taxic evolution in the fossil record, traditional paleontologic genera and families need not be rejected in favor of cladistically-defined taxa.

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Shifts in sexual dimorphism across a mass extinction in ostracods: implications for sexual selection as a factor in extinction risk

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.0730 ◽

2020 ◽

Vol 287 (1933) ◽

pp. 20200730

Author(s):

Maria João Fernandes Martins ◽

Gene Hunt ◽

Carmi Milagros Thompson ◽

Rowan Lockwood ◽

John P. Swaddle ◽

...

Keyword(s):

Sexual Selection ◽

Sexual Dimorphism ◽

Mass Extinction ◽

Fossil Record ◽

Extinction Risk ◽

The United States ◽

Mass Extinctions ◽

Allocation Of Resources ◽

Male Investment ◽

The Rich

Sexual selection often favours investment in expensive sexual traits that help individuals compete for mates. In a rapidly changing environment, however, allocation of resources to traits related to reproduction at the expense of those related to survival may elevate extinction risk. Empirical testing of this hypothesis in the fossil record, where extinction can be directly documented, is largely lacking. The rich fossil record of cytheroid ostracods offers a unique study system in this context: the male shell is systematically more elongate than that of females, and thus the sexes can be distinguished, even in fossils. Using mixture models to identify sex clusters from size and shape variables derived from the digitized valve outlines of adult ostracods, we estimated sexual dimorphism in ostracod species before and after the Cretaceous/Palaeogene mass extinction in the United States Coastal Plain. Across this boundary, we document a substantial shift in sexual dimorphism, driven largely by a pronounced decline in the taxa with dimorphism indicating both very high and very low male investment. The shift away from high male investment, which arises largely from evolutionary changes within genera that persist through the extinction, parallels extinction selectivity previously documented during the Late Cretaceous under a background extinction regime. Our results suggest that sexual selection and the allocation of resources towards survival versus reproduction may be an important factor for species extinction during both background and mass extinctions.

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Olson's Gap or Olson's Extinction? A Bayesian tip-dating approach to resolving stratigraphic uncertainty

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.0154 ◽

2020 ◽

Vol 287 (1928) ◽

pp. 20200154

Author(s):

Neil Brocklehurst

Keyword(s):

Mass Extinction ◽

Fossil Record ◽

Trophic Structure ◽

Terrestrial Ecosystems ◽

Morphological Data ◽

Mass Extinctions ◽

Faunal Turnover ◽

Dating Methods ◽

Adaptive Radiations ◽

Stratigraphic Uncertainty

Adaptive radiations and mass extinctions are of critical importance in structuring terrestrial ecosystems. However, the causes and progress of these transitions often remain controversial, in part because of debates surrounding the completeness of the fossil record and biostratigraphy of the relevant fossil-bearing formations. The early–middle Permian, when a substantial faunal turnover in tetrapods coincided with a restructuring of the trophic structure of ecosystems, is such a time. Some have suggested the transition is obscured by a gap in the tetrapod fossil record (Olson's Gap), while others suggest a correlation between North American and Russian tetrapod-bearing formations allows the interval to be documented in detail. The latter biostratigraphic scheme has been used to support a mass extinction at this time (Olson's Extinction). Bayesian tip-dating methods used frequently in phylogenetics are employed to resolve this debate. Bayes factors are used to compare the results of analyses incorporating tip age priors based on different stratigraphic hypotheses, to show which stratigraphic scheme best fits the morphological data and phylogeny. Olson's Gap is rejected, and the veracity of Olson's Extinction is given further support. Tip-dating approaches have great potential to resolve debates surrounding the stratigraphic ages of critical formations where appropriate morphological data is available.

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Confidence intervals for pulsed mass extinction events

Paleobiology ◽

10.1666/06056.1 ◽

2007 ◽

Vol 33 (2) ◽

pp. 324-336 ◽

Cited By ~ 27

Author(s):

Steve C. Wang ◽

Philip J. Everson

Keyword(s):

Confidence Intervals ◽

Mass Extinction ◽

Fossil Record ◽

Marine Invertebrates ◽

Ratio Test ◽

Mass Extinctions ◽

Data Set ◽

Triassic Boundary ◽

Multiple Pulses ◽

Extinction Events

Many authors have proposed scenarios for mass extinctions that consist of multiple pulses or stages, but little work has been done on accounting for the Signor-Lipps effect in such extinction scenarios. Here we introduce a method for computing confidence intervals for the time or stratigraphic distance separating two extinction pulses in a pulsed extinction event, taking into account the incompleteness of the fossil record. We base our method on a flexible likelihood ratio test framework that is able to test whether the fossil record is consistent with any extinction scenario, whether simultaneous, pulsed, or otherwise. As an illustration, we apply our method to a data set on marine invertebrates from the Permo-Triassic boundary of Meishan, China. Using this data set, we show that the fossil record of ostracodes and that of brachiopods are each consistent with simultaneous extinction, and that these two extinction pulses are separated by 720,000 to 1.2 million years with 95% confidence. With appropriate data, our method could also be applied in other situations, such as tests of origination patterns, coordinated stasis, and recovery after a mass extinction.

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Biogeochemical disruptions across the Cretaceous-Paleogene boundary : insights from sulfur isotopes

10.5194/egusphere-egu21-14669 ◽

2021 ◽

Author(s):

Arbia Jouini

Keyword(s):

Mass Extinction ◽

Environmental Changes ◽

Sea Water ◽

Sulfur Isotopes ◽

Deep Understanding ◽

Sulfur Cycle ◽

Mass Extinctions ◽

Deccan Volcanism ◽

Organic Carbon Burial ◽

Early Paleocene

Biogeochemical disruptions across the Cretaceous-Paleogene boundary : insights from sulfur isotopes&#160;Arbia JOUINI1*, Guillaume PARIS1, Guillaume CARO1, Annachiara BARTOLINI21 Centre de Recherches P&#233;trographiques et G&#233;ochimiques, CRPG-CNRS, UMR7358, ,15 rue Notre Dame des Pauvres, BP20, 54501Vandoeuvre-l&#232;s-Nancy, France, email:[email protected]2 Mus&#233;um National D&#8217;Histoire Naturelle, D&#233;partement Origines & Evolution, CR2P MNHN, CNRS, Sorbonne Universit&#233;, 8 rue Buffon CP38, 75005 Paris, France&#160;The Cretaceous&#8211;Paleogene (KPg) mass extinction event 66 million years ago witnessed one of the &#8216;Big Five&#8217; mass extinctions of the Phanerozoic. Two major catastrophic events, the Chicxulub asteroid impact and the Deccan trap eruptions, were involved in complex climatic and environmental changes that culminated in the mass extinction including oceanic biogenic carbonate crisis, sea water chemistry and ocean oxygen level changes. Deep understanding of the coeval sulfur biogeochemical cycle may help to better constrain and quantify these parameters.Here we present the first stratigraphic high resolution isotopic compositions of carbonate associated sulfate (CAS) based on monospecific planktic and benthic foraminifers' samples during the Maastrichtian-Danian transition from IODP pacific site 1209C. Primary &#948;34SCAS data suggests that there was a major perturbation of sulfur cycle around the KPg transition with rapid fluctuations (100-200kyr) of about 2-4&#8240; (&#177;0.54&#8240;, 2SD) during the late Maastrichtian followed by a negative excursion in &#948;34SCAS of 2-3&#8240; during the early Paleocene.An increase in oxygen levels associated with a decline in organic carbon burial, related to a collapse in primary productivity, may have led to the early Paleocene &#948;34SCAS negative shift via a significant drop in microbial sulfate reduction. Alternatively, Deccan volcanism could also have played a role and impacted the sulfur cycle via direct input of isotopically light sulfur to the ocean. A revised correlation between &#948;34SCAS data reported in this study and a precise dating of the Deccan volcanism phases would allow us to explore this hypothesis.Keywords : KPg boundary, Sulphur cycle, cycle du calcium, Planktic and benthic foraminifera&#160;

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