scholarly journals Pre- versus post-mass extinction divergence of Mesozoic marine reptiles dictated by time-scale dependence of evolutionary rates

2017 ◽  
Vol 284 (1854) ◽  
pp. 20170241 ◽  
Author(s):  
Ryosuke Motani ◽  
Da-yong Jiang ◽  
Andrea Tintori ◽  
Cheng Ji ◽  
Jian-dong Huang
Keyword(s):  
High Resolution ◽  
Time Scale ◽  
Mass Extinction ◽  
Divergence Time ◽  
Temporal Characteristic ◽  
Evolutionary Rates ◽  
Morphological Data ◽  
Mass Extinctions ◽  
Marine Reptiles ◽  
Permian Mass Extinction

The fossil record of a major clade often starts after a mass extinction even though evolutionary rates, molecular or morphological, suggest its pre-extinction emergence (e.g. squamates, placentals and teleosts). The discrepancy is larger for older clades, and the presence of a time-scale-dependent methodological bias has been suggested, yet it has been difficult to avoid the bias using Bayesian phylogenetic methods. This paradox raises the question of whether ecological vacancies, such as those after mass extinctions, prompt the radiations. We addressed this problem by using a unique temporal characteristic of the morphological data and a high-resolution stratigraphic record, for the oldest clade of Mesozoic marine reptiles, Ichthyosauromorpha. The evolutionary rate was fastest during the first few million years of ichthyosauromorph evolution and became progressively slower over time, eventually becoming six times slower. Using the later slower rates, estimates of divergence time become excessively older. The fast, initial rate suggests the emergence of ichthyosauromorphs after the end-Permian mass extinction, matching an independent result from high-resolution stratigraphic confidence intervals. These reptiles probably invaded the sea as a new ecosystem was formed after the end-Permian mass extinction. Lack of information on early evolution biased Bayesian clock rates.

scholarly journals Devonian bryozoan extinction and diversification

1992 ◽  
Vol 6 ◽  
pp. 136-136
Author(s):  
Alan S. Horowitz ◽  
Joseph F. Pachut
Keyword(s):  
Mass Extinction ◽  
Taxonomic Diversity ◽  
Mass Extinctions ◽  
Random Mass ◽  
Number Of Species ◽  
Rugose Corals ◽  
Nomina Dubia ◽  
Extinction Model ◽  
Permian Mass Extinction ◽  
Devonian Extinction

The names proposed world-wide for Devonian bryozoans have been evaluated with respect to replaced names, synonyms, and nomina dubia [Horowitz and Pachut (1993), Journal of Paleontology, in press]. The resulting list contains 1738 specific names assigned to 199 genera in 45 families. Approximately 75% of Devonian bryozoan species are reported from a single stage. Not more than 10%, and usually 4–6%, of the species reported in any Devonian stage are also reported in the succeeding stage.The largest decrease in observed bryozoan diversity occurs between the Givetian and Frasnian stages, reducing the number of species by 77%, genera by 64%, and families by 42%. These values are less than those reported for the range-through method for the entire fauna of the Permian mass extinction (Raup, 1979) but larger than percentage extinctions (presumably based on range-though data) for four other Phanerozoic mass extinctions tabulated by Valentine and Walker (1987).The range-through method dampens the observed differences in taxonomic diversity among Devonian stages at all taxonomic levels. The range-through number of species/stage is based upon both direct applications of the range-through method and on the assignment of ranges known only to early, middle and late Devonian to include appropriate Devonian stages. Generic and familial diversity increases monotonically from Lochkovian through Givetian stages. Thereafter (Givetian to Frasnian), range-through values for specific (69%), generic (31%), and familial diversity (10%) decrease. Specific and familial decreases across the Givetian-Frasnian boundary are comparable to those reported for non-Permian mass extinctions by Valentine and Walker, but the generic decrease is not as great. These results are consistent with Valentine and Walker's random mass extinction model.Observed bryozoan diversity across the Frasnian-Famennian boundary increases while values calculated using the range-through method decrease by approximately 5–15%. This does not suggest a major bryozoan extinction event. Conversely, the decrease in bryozoan diversity across the Givetian-Frasnian interval is similar to an important Devonian extinction among rugose corals. The reason(s) for these extinctions is not yet clear. With respect to Devonian bryozoans, our inadequate understanding of the cause(s) of mass extinctions and the relatively coarse resolution of the stadial timescale does not permit differentiating between gradual or catastrophic scenarios.

Primary productivity, deoxygenation, and the Gulliver-absence effect determine bivalve body size following the end-Permian mass extinction

2020 ◽  
Author(s):  
Melanie Tietje ◽  
William J. Foster ◽  
Jana Gliwa ◽  
Clara Lembke ◽  
Autumn Pugh ◽  
...  
Keyword(s):  
Body Size ◽  
Ocean Circulation ◽  
Mass Extinction ◽  
The Body ◽  
Large Species ◽  
Mass Extinctions ◽  
Shell Size ◽  
Body Sizes ◽  
Permian Mass Extinction ◽  
The Impact

<p> The impact of mass extinctions on the body sizes of animals has received considerable attention and debate, as to whether the reduced size of post-extinction organisms is due to the selective extinction of large species, absence of large species as a stochastic effect of low-diversity faunas, or a size decrease within surviving genera and species. Here, we investigated the body sizes of bivalves following the end-Permian mass extinction event and show that the shell size increase of bivalve genera was driven by both evolutionary and ecophenotypic responses. First, some genera show significant increases in body size with the evolution of new species. Further, the same genera record significant within-species increases in average and maximum body size into the late Induan, indicating that ecophenotypic changes were also involved on long-term body size trends. These increases are associated with invigorated ocean circulation, improved oxygenation of the seafloor, and probably increased food supply.</p>

scholarly journals Supplemental Material: Mercury fluxes record regional volcanism in the South China craton prior to the end-Permian mass extinction

2020 ◽  
Author(s):  
Jun Shen ◽  
et al.
Keyword(s):  
South China ◽  
Time Scale ◽  
Analytical Methods ◽  
Mass Extinction ◽  
Volcanic Ash ◽  
Geological Time ◽  
Geological Time Scale ◽  
Mercury Fluxes ◽  
South China Craton ◽  
Permian Mass Extinction

Descriptions of studied sections, analytical methods, mercury as volcanic proxy, host of Hg in sediments, and geological time scale and volcanic ash distributions.<br>

Modeling bivalve diversification: the effect of interaction on a macroevolutionary system

Paleobiology ◽  
1988 ◽  
Vol 14 (4) ◽  
pp. 364-369 ◽  
Author(s):  
Arnold I. Miller ◽  
J. John Sepkoski
Keyword(s):  
Late Cretaceous ◽  
Mass Extinction ◽  
Logistic Model ◽  
Slow Growth ◽  
The Other ◽  
Mass Extinctions ◽  
Late Permian ◽  
Two Phase ◽  
Global Diversity ◽  
Permian Mass Extinction

The global diversification of the class Bivalvia has historically received two conflicting interpretations. One is that a major upturn in diversification was associated with, and a consequence of, the Late Permian mass extinction. The other is that mass extinctions have had little influence and that bivalves have experienced slow but nearly steady exponential diversification through most of their history, unaffected by interactions with other clades. We find that the most likely explanation lies between these two interpretations. Through most of the Phanerozoic, the diversity of bivalves did indeed exhibit slow growth, which was not substantially altered by mass extinctions. However, the presence of “hyperexponential bursts” in diversification during the initial Ordovician radiation and following the Late Permian and Late Cretaceous mass extinctions suggests a more complex history in which a higher characteristic diversification rate was dampened through most of the Phanerozoic. The observed pattern can be accounted for with a two-phase coupled (i.e., interactive) logistic model, where one phase is treated as the “bivalves” and the other phase is treated as a hypothetical group of clades with which the “bivalves” might have interacted. Results of this analysis suggest that interactions with other taxa have substantially affected bivalve global diversity through the Phanerozoic.

scholarly journals Decoupling of morphological disparity and taxic diversity during the adaptive radiation of anomodont therapsids

2013 ◽  
Vol 280 (1768) ◽  
pp. 20131071 ◽  
Author(s):  
Marcello Ruta ◽  
Kenneth D. Angielczyk ◽  
Jörg Fröbisch ◽  
Michael J. Benton
Keyword(s):  
Mass Extinction ◽  
Phylogenetic Diversity ◽  
Mass Extinctions ◽  
Triassic Boundary ◽  
Morphological Disparity ◽  
Morphological Novelty ◽  
Adaptive Radiations ◽  
Permian Mass Extinction ◽  
Original Potential ◽  
Taxic Diversity

Adaptive radiations are central to macroevolutionary theory. Whether triggered by acquisition of new traits or ecological opportunities arising from mass extinctions, it is debated whether adaptive radiations are marked by initial expansion of taxic diversity or of morphological disparity (the range of anatomical form). If a group rediversifies following a mass extinction, it is said to have passed through a macroevolutionary bottleneck, and the loss of taxic or phylogenetic diversity may limit the amount of morphological novelty that it can subsequently generate. Anomodont therapsids, a diverse clade of Permian and Triassic herbivorous tetrapods, passed through a bottleneck during the end-Permian mass extinction. Their taxic diversity increased during the Permian, declined significantly at the Permo–Triassic boundary and rebounded during the Middle Triassic before the clade's final extinction at the end of the Triassic. By sharp contrast, disparity declined steadily during most of anomodont history. Our results highlight three main aspects of adaptive radiations: (i) diversity and disparity are generally decoupled; (ii) models of radiations following mass extinctions may differ from those triggered by other causes (e.g. trait acquisition); and (iii) the bottleneck caused by a mass extinction means that a clade can emerge lacking its original potential for generating morphological variety.

scholarly journals The Luoping biota: exceptional preservation, and new evidence on the Triassic recovery from end-Permian mass extinction

2010 ◽  
Vol 278 (1716) ◽  
pp. 2274-2282 ◽  
Author(s):  
Shi-xue Hu ◽  
Qi-yue Zhang ◽  
Zhong-Qiang Chen ◽  
Chang-yong Zhou ◽  
Tao Lü ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Middle Triassic ◽  
Marine Ecosystem ◽  
Marine Ecosystems ◽  
Trophic Levels ◽  
Marine Animals ◽  
Exceptional Preservation ◽  
Marine Reptiles ◽  
Biotic Recovery ◽  
Permian Mass Extinction

The timing and nature of biotic recovery from the devastating end-Permian mass extinction (252 Ma) are much debated. New studies in South China suggest that complex marine ecosystems did not become re-established until the middle–late Anisian (Middle Triassic), much later than had been proposed by some. The recently discovered exceptionally preserved Luoping biota from the Anisian Stage of the Middle Triassic, Yunnan Province and southwest China shows this final stage of community assembly on the continental shelf. The fossil assemblage is a mixture of marine animals, including abundant lightly sclerotized arthropods, associated with fishes, marine reptiles, bivalves, gastropods, belemnoids, ammonoids, echinoderms, brachiopods, conodonts and foraminifers, as well as plants and rare arthropods from nearby land. In some ways, the Luoping biota rebuilt the framework of the pre-extinction latest Permian marine ecosystem, but it differed too in profound ways. New trophic levels were introduced, most notably among top predators in the form of the diverse marine reptiles that had no evident analogues in the Late Permian. The Luoping biota is one of the most diverse Triassic marine fossil Lagerstätten in the world, providing a new and early window on recovery and radiation of Triassic marine ecosystems some 10 Myr after the end-Permian mass extinction.

scholarly journals Supplemental Material: Mercury fluxes record regional volcanism in the South China craton prior to the end-Permian mass extinction

2020 ◽  
Author(s):  
Jun Shen ◽  
et al.
Keyword(s):  
South China ◽  
Time Scale ◽  
Analytical Methods ◽  
Mass Extinction ◽  
Volcanic Ash ◽  
Geological Time ◽  
Geological Time Scale ◽  
Mercury Fluxes ◽  
South China Craton ◽  
Permian Mass Extinction

Descriptions of studied sections, analytical methods, mercury as volcanic proxy, host of Hg in sediments, and geological time scale and volcanic ash distributions.<br>

scholarly journals Machine learning (decision tree analysis) identifies ecological selectivity patterns across the end-Permian mass extinction

2020 ◽  
Author(s):  
William J. Foster ◽  
Georgy Ayzel ◽  
Terry T. Isson ◽  
Maria Mutti ◽  
Martin Aberhan
Keyword(s):  
Machine Learning ◽  
Decision Tree ◽  
Mass Extinction ◽  
Extinction Risk ◽  
Machine Learning Algorithms ◽  
Stationary Mode ◽  
Mass Extinctions ◽  
Tree Algorithms ◽  
Extinction Selectivity ◽  
Permian Mass Extinction

AbstractDecision tree algorithms are rarely utilized in paleontological research, and here we show that machine learning algorithms can be used to identify determinants of extinction as well as predict extinction risk. This application of decision tree algorithms is important because the ecological selectivity of mass extinctions can reveal critical information on organismic traits as key determinants of extinction and hence the causes of extinction. To understand which factors led to the mass extinction of life during an extreme global warming event, we quantified the ecological selectivity of marine extinctions in the well-studied South China region during the end-Permian mass extinction using the categorized gradient boosting algorithm. We find that extinction selectivity varies between different groups of organisms and that a synergy of multiple environmental stressors best explains the overall end-Permian extinction selectivity pattern. Extinction risk was greater for genera that were limited to deep-water habitats, had a stationary mode of life, possessed a siliceous skeleton or, less critically, had calcitic skeletons. These selective losses directly link the extinction to the environmental effects of rapid injections of carbon dioxide into the ocean-atmosphere system, specifically the combined effects of expanded oxygen minimum zones, rapid warming, and ocean acidification.

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