scholarly journals Positive Sulfate Sulfur Isotope Excursion Indicates Large-Scale Pyrite Burial and Marine Anoxia during the End–Triassic Mass Extinction

2020 ◽  
Author(s):  
Tianchen He ◽  
Jacopo Dal Corso ◽  
Robert J. Newton ◽  
Paul B. Wignall ◽  
Benjamin J.W. Mills ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Large Scale ◽  
Sulfur Isotope ◽  
Sulfate Sulfur

scholarly journals An enormous sulfur isotope excursion indicates marine anoxia during the end-Triassic mass extinction

2020 ◽  
Vol 6 (37) ◽  
pp. eabb6704
Author(s):  
Tianchen He ◽  
Jacopo Dal Corso ◽  
Robert J. Newton ◽  
Paul B. Wignall ◽  
Benjamin J. W. Mills ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Large Scale ◽  
Sulfur Isotope ◽  
Oxygen Demand ◽  
Methane Flux ◽  
Global Scale ◽  
Late Triassic ◽  
Carbonate Associated Sulfate ◽  
Water Oxygen

The role of ocean anoxia as a cause of the end-Triassic marine mass extinction is widely debated. Here, we present carbonate-associated sulfate δ34S data from sections spanning the Late Triassic–Early Jurassic transition, which document synchronous large positive excursions on a global scale occurring in ~50 thousand years. Biogeochemical modeling demonstrates that this S isotope perturbation is best explained by a fivefold increase in global pyrite burial, consistent with large-scale development of marine anoxia on the Panthalassa margin and northwest European shelf. This pyrite burial event coincides with the loss of Triassic taxa seen in the studied sections. Modeling results also indicate that the pre-event ocean sulfate concentration was low (<1 millimolar), a common feature of many Phanerozoic deoxygenation events. We propose that sulfate scarcity preconditions oceans for the development of anoxia during rapid warming events by increasing the benthic methane flux and the resulting bottom-water oxygen demand.

scholarly journals Large-Scale Hybridisation as an Extinction Threat to the Suweon Treefrog (Hylidae: Dryophytes suweonensis)

Animals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 764 ◽  
Author(s):  
Amaël Borzée ◽  
Jonathan J. Fong ◽  
Hoa Quynh Nguyen ◽  
Yikweon Jang
Keyword(s):  
Mitochondrial Dna ◽  
Species Distribution ◽  
Dna Sequences ◽  
Mass Extinction ◽  
Large Scale ◽  
Natural Habitats ◽  
Commensal Species ◽  
Polymorphic Microsatellites ◽  
Sixth Mass Extinction ◽  
Threaten Species

Amphibians are in the midst of a sixth mass extinction, and human activities play a major role in pushing species towards extinction. Landscape anthropisation has impacts that indirectly threaten species, in addition to the obvious destruction of natural habitats. For instance, land modification may bring human-commensal species in contact with sister-clades from which they were previously isolated. The species in these new contact zones are then able to hybridise to the point of reaching lineage fusion, through which the gene pool of the two species merges and one of the parental lineages becomes extirpated. Here, we documented the patterns of hybridisation between the spatially restricted D. suweonensis and the widespread D. japonicus. On the basis of the analysis of Cytochrome c oxidase subunit I mitochondrial DNA sequences (404 individuals from 35 sites) and six polymorphic microsatellites (381 individuals from 34 sites), we revealed a generalised, bi-directional, and geographically widespread hybridisation between the two species. Evidence of fertile back-crosses is provided by relatively high numbers of individuals in cyto-nuclear disequilibrium, as well as the presence of hybrid individuals further south than the species distribution limit, determined on the basis of call properties. Hybridisation is an additional threat to the endangered D. suweonensis.

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 The Origin and Early Evolution of the Legumes are a Complex Paleopolyploid Phylogenomic Tangle closely associated with the Cretaceous-Paleogene (K-Pg) Boundary

2019 ◽  
Author(s):  
Erik J.M. Koenen ◽  
Dario I. Ojeda ◽  
Royce Steeves ◽  
Jérémy Migliore ◽  
Freek T. Bakker ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Large Scale ◽  
Genomic Sequence ◽  
Sequence Data ◽  
Incomplete Lineage Sorting ◽  
Nuclear Gene ◽  
Early Evolution ◽  
Large Set ◽  
Gene Trees ◽  
The Family

AbstractThe consequences of the Cretaceous-Paleogene (K-Pg) boundary (KPB) mass extinction for the evolution of plant diversity are poorly understood, even although evolutionary turnover of plant lineages at the KPB is central to understanding the assembly of the Cenozoic biota. One aspect that has received considerable attention is the apparent concentration of whole genome duplication (WGD) events around the KPB, which may have played a role in survival and subsequent diversification of plant lineages. In order to gain new insights into the origins of Cenozoic biodiversity, we examine the origin and early evolution of the legume family, one of the most important angiosperm clades that rose to prominence after the KPB and for which multiple WGD events are found to have occurred early in its evolution. The legume family (Leguminosae or Fabaceae), with c. 20.000 species, is the third largest family of Angiospermae, and is globally widespread and second only to the grasses (Poaceae) in economic importance. Accordingly, it has been intensively studied in botanical, systematic and agronomic research, but a robust phylogenetic framework and timescale for legume evolution based on large-scale genomic sequence data is lacking, and key questions about the origin and early evolution of the family remain unresolved. We extend previous phylogenetic knowledge to gain insights into the early evolution of the family, analysing an alignment of 72 protein-coding chloroplast genes and a large set of nuclear genomic sequence data, sampling thousands of genes. We use a concatenation approach with heterogeneous models of sequence evolution to minimize inference artefacts, and evaluate support and conflict among individual nuclear gene trees with internode certainty calculations, a multi-species coalescent method, and phylogenetic supernetwork reconstruction. Using a set of 20 fossil calibrations we estimate a revised timeline of legume evolution based on a selection of genes that are both informative and evolving in an approximately clock-like fashion. We find that the root of the family is particularly difficult to resolve, with strong conflict among gene trees suggesting incomplete lineage sorting and/or reticulation. Mapping of duplications in gene family trees suggest that a WGD event occurred along the stem of the family and is shared by all legumes, with additional nested WGDs subtending subfamilies Papilionoideae and Detarioideae. We propose that the difficulty of resolving the root of the family is caused by a combination of ancient polyploidy and an alternation of long and very short internodes, shaped respectively by extinction and rapid divergence. Our results show that the crown age of the legumes dates back to the Maastrichtian or Paleocene and suggests that it is most likely close to the KPB. We conclude that the origin and early evolution of the legumes followed a complex history, in which multiple nested polyploidy events coupled with rapid diversification are associated with the mass extinction event at the KPB, ultimately underpinning the evolutionary success of the Leguminosae in the Cenozoic.

scholarly journals The extinction and survival of sharks across the end-Cretaceous mass extinction

2021 ◽  
Author(s):  
Mohamad Bazzi ◽  
Nicolás E. Campione ◽  
Per E. Ahlberg ◽  
Henning Blom ◽  
Benjamin P. Kear
Keyword(s):  
Mass Extinction ◽  
Large Scale ◽  
Dental Morphology ◽  
Mass Extinctions ◽  
Morphological Response ◽  
Geometric Morphometric ◽  
Marine Predators ◽  
Extinction Event ◽  
Mass Extinction Event ◽  
Early Paleogene

AbstractSharks (Selachimorpha) are iconic marine predators that have survived multiple mass extinctions over geologic time. Their fossil record is represented by an abundance of teeth, which traditionally formed the basis for reconstructing large-scale diversity changes among different selachimorph clades. By contrast, corresponding patterns in shark ecology, as measured through morphological disparity, have received comparatively limited analytical attention. Here, we use a geometric morphometric approach to comprehensively examine the dental morphology of multiple shark lineages traversing the catastrophic end-Cretaceous mass extinction — this event terminated the Mesozoic Era 66 million years ago. Our results show that selachimorphs maintained virtually static levels of dental disparity in most of their constituent clades during the Cretaceous/Paleogene transition. Nevertheless, selective extinctions did impact on apex predator lineages characterized by triangular blade-like teeth, and in particular, lamniforms including the dominant Cretaceous anacoracids. Other groups, such as, triakid carcharhiniforms, squalids, and hexanchids, were seemingly unaffected. Finally, while some lamniform lineages experienced morphological depletion, others underwent a post-extinction disparity increase, especially odontaspidids, which are typified by narrow-cusped teeth adapted for feeding on fishes. This disparity shift coincides with the early Paleogene radiation of teleosts, a possible prey source, as well as the geographic relocation of shark disparity ‘hotspots’, perhaps indicating a regionally disjunct pattern of extinction recovery. Ultimately, our study reveals a complex morphological response to the end-Cretaceous mass extinction event, the dynamics of which we are only just beginning to understand.

The effects of CO2 increase and its link to the mass extincton at the Permo-Triassic boundary

2021 ◽  
Author(s):  
Despina Zoura ◽  
Daniel J. Hill ◽  
Stephen J. Hunter ◽  
Alan M. Haywood ◽  
Paul B. Wignall
Keyword(s):  
Mass Extinction ◽  
General Circulation ◽  
Large Scale ◽  
Circulation Model ◽  
Marine Species ◽  
Triassic Boundary ◽  
Tropical Regions ◽  
Dry Conditions ◽  
The Uk ◽  
Precipitation Changes

&lt;p&gt;The Permo&amp;#8211;Triassic Boundary (PTB) marks a time of profound climatic change. Near the PTB (~252 Ma), the largest known mass extinction occurred with more than 90% of marine species and 70% of terrestrial species became extinct. The mass extinction is linked to a massive warming event at the PTB, where tropical regions became too hot for survival ofspecies. The increase in atmospheric CO&lt;sub&gt;2&lt;/sub&gt; during the Permian and the PTB is mainly attributed to the decrease of chemically weatherable fresh silicate rock due to orogenesis, and the CO&lt;sub&gt;2&lt;/sub&gt; released in the atmosphere from the Siberian Traps. In this study, we use the UK Met Office fully coupled HadCM3L General Circulation Model (GCM) to perform Permo-Triassic climate simulations with different atmospheric CO&lt;sub&gt;2&lt;/sub&gt; values that encompass most of the estimates of atmospheric CO&lt;sub&gt;2&lt;/sub&gt; concentration during this time, to provide more insights about the climate changes during the end Permian &amp;#8211; early Triassic. Specifically, we focus on: a) the spatial extension of dry conditions/lethally hot temperatures under different CO&lt;sub&gt;2&lt;/sub&gt; conditions, b) the seasonal surface temperature difference and precipitation changes at higher latitudes and c) the effects of increased atmospheric CO&lt;sub&gt;2&lt;/sub&gt; on the large-scale wind and monsoonal circulation.&amp;#160;&lt;/p&gt;

scholarly journals Stable isotope analysis of human bone from Ganj Dareh, Iran, ca. 10,100 calBP

PLoS ONE ◽  
2021 ◽  
Vol 16 (3) ◽  
pp. e0247569
Author(s):  
Deborah C. Merrett ◽  
Christina Cheung ◽  
Christopher Meiklejohn ◽  
Michael P. Richards
Keyword(s):  
Stable Isotopes ◽  
Large Scale ◽  
Sulfur Isotope ◽  
Age Groups ◽  
Human Bone ◽  
Early Holocene ◽  
Bone Collagen ◽  
Zagros Mountains ◽  
Isotopic Compositions ◽  
Significant Difference

We report here on stable carbon, nitrogen, and sulfur isotope values from bone collagen of human (n = 20) and faunal (n = 11) remains from the Early Neolithic site of Ganj Dareh, Iran, dating to ca. 10,100 cal. BP. Our focus explores how isotope values of human bone vary by age and sex, and evaluates dietary practices at this site. It also provides a baseline for future studies of subsistence in the early Holocene Central Zagros Mountains, from the site with the first evidence for human ovicaprid management in the Near East. Human remains include individuals of all age groups for dietary reconstruction, as well two Ottoman intrusive burials for temporal and cultural comparison. All analyzed individuals exhibited δ13C and δ15N values consistent with a diet based heavily on C3 terrestrial sources. There is no statistically significant difference between the isotopic compositions of the two sexes, though males appear to show larger variations compared to females. Interesting patterns in the isotopic compositions of the subadults suggested weaning children may be fed with supplements with distinctive δ13C values. Significant difference in sulfur isotope values between humans and fauna could be the earliest evidence of transhumance and could identify one older adult male as a possible transhumant shepherd. Both Ottoman individuals had distinctively different δ13C, δ15N, and δ34S values compared to the Neolithic individuals. This is the first large scale analysis of human stable isotopes from the eastern end of the early Holocene Fertile Crescent. It provides a baseline for future intersite exploration of stable isotopes and insight into the lifeways, health, and processes of neolithisation associated with the origins of goat domestication at Ganj Dareh and the surrounding Central Zagros.

Climate modelling of mass-extinction events: a review

2009 ◽  
Vol 8 (3) ◽  
pp. 207-212 ◽  
Author(s):  
Georg Feulner
Keyword(s):  
Mass Extinction ◽  
Plate Tectonics ◽  
Large Scale ◽  
Volcanic Eruptions ◽  
Biological Species ◽  
Future Research ◽  
Climate Modelling ◽  
Mass Extinctions ◽  
Extinction Events ◽  
Mass Extinction Events

AbstractDespite tremendous interest in the topic and decades of research, the origins of the major losses of biodiversity in the history of life on Earth remain elusive. A variety of possible causes for these mass-extinction events have been investigated, including impacts of asteroids or comets, large-scale volcanic eruptions, effects from changes in the distribution of continents caused by plate tectonics, and biological factors, to name but a few. Many of these suggested drivers involve or indeed require changes of Earth's climate, which then affect the biosphere of our planet, causing a global reduction in the diversity of biological species. It can be argued, therefore, that a detailed understanding of these climatic variations and their effects on ecosystems are prerequisites for a solution to the enigma of biological extinctions. Apart from investigations of the paleoclimate data of the time periods of mass extinctions, climate-modelling experiments should be able to shed some light on these dramatic events. Somewhat surprisingly, however, only a few comprehensive modelling studies of the climate changes associated with extinction events have been undertaken. These studies will be reviewed in this paper. Furthermore, the role of modelling in extinction research in general and suggestions for future research are discussed.

scholarly journals The latitudinal diversity gradient of tetrapods across the Permo-Triassic mass extinction and recovery interval

2020 ◽  
Vol 287 (1929) ◽  
pp. 20201125 ◽  
Author(s):  
Bethany J. Allen ◽  
Paul B. Wignall ◽  
Daniel J. Hill ◽  
Erin E. Saupe ◽  
Alexander M. Dunhill
Keyword(s):  
Mass Extinction ◽  
Large Scale ◽  
Middle Triassic ◽  
Global Climate ◽  
Time Interval ◽  
Late Permian ◽  
Biodiversity Patterns ◽  
Latitudinal Diversity Gradient ◽  
Earth History ◽  
Diversity Gradient

The decline in species richness from the equator to the poles is referred to as the latitudinal diversity gradient (LDG). Higher equatorial diversity has been recognized for over 200 years, but the consistency of this pattern in deep time remains uncertain. Examination of spatial biodiversity patterns in the past across different global climate regimes and continental configurations can reveal how LDGs have varied over Earth history and potentially differentiate between suggested causal mechanisms. The Late Permian–Middle Triassic represents an ideal time interval for study, because it is characterized by large-scale volcanic episodes, extreme greenhouse temperatures and the most severe mass extinction event in Earth history. We examined terrestrial and marine tetrapod spatial biodiversity patterns using a database of global tetrapod occurrences. Terrestrial tetrapods exhibit a bimodal richness distribution throughout the Late Permian–Middle Triassic, with peaks in the northern low latitudes and southern mid-latitudes around 20–40° N and 60° S, respectively. Marine reptile fossils are known almost exclusively from the Northern Hemisphere in the Early and Middle Triassic, with highest diversity around 20° N. Reconstructed terrestrial LDGs contrast strongly with the generally unimodal gradients of today, potentially reflecting high global temperatures and prevailing Pangaean super-monsoonal climate system during the Permo-Triassic.

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