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 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 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 Archosauriform footprints in the Lower Triassic of Western Alps and their role in understanding the effects of the Permian-Triassic hyperthermal

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10522
Author(s):  
Fabio Massimo Petti ◽  
Heinz Furrer ◽  
Enrico Collo ◽  
Edoardo Martinetto ◽  
Massimo Bernardi ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Lower Triassic ◽  
Western Alps ◽  
Large Igneous Province ◽  
Early Triassic ◽  
Triassic Boundary ◽  
Habitable Zones ◽  
Single Well ◽  
Permian Mass Extinction ◽  
Permian Triassic Boundary

The most accepted killing model for the Permian-Triassic mass extinction (PTME) postulates that massive volcanic eruption (i.e., the Siberian Traps Large Igneous Province) led to geologically rapid global warming, acid rain and ocean anoxia. On land, habitable zones were drastically reduced, due to the combined effects of heating, drought and acid rains. This hyperthermal had severe effects also on the paleobiogeography of several groups of organisms. Among those, the tetrapods, whose geographical distribution across the end-Permian mass extinction (EPME) was the subject of controversy in a number of recent papers. We here describe and interpret a new Early Triassic (?Olenekian) archosauriform track assemblage from the Gardetta Plateau (Briançonnais, Western Alps, Italy) which, at the Permian-Triassic boundary, was placed at about 11° North. The tracks, both arranged in trackways and documented by single, well-preserved imprints, are assigned to Isochirotherium gardettensis ichnosp. nov., and are here interpreted as produced by a non-archosaurian archosauriform (erytrosuchid?) trackmaker. This new discovery provides further evidence for the presence of archosauriformes at low latitudes during the Early Triassic epoch, supporting a model in which the PTME did not completely vacate low-latitude lands from tetrapods that therefore would have been able to cope with the extreme hot temperatures of Pangaea mainland.

scholarly journals Rapid enhancement of chemical weathering recorded by extremely light seawater lithium isotopes at the Permian–Triassic boundary

2018 ◽  
Vol 115 (15) ◽  
pp. 3782-3787 ◽  
Author(s):  
He Sun ◽  
Yilin Xiao ◽  
Yongjun Gao ◽  
Guijie Zhang ◽  
John F. Casey ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Chemical Weathering ◽  
Triassic Boundary ◽  
Isotopic Signatures ◽  
Siberian Traps ◽  
Li Isotope ◽  
Continental Weathering ◽  
Excessive Nutrients ◽  
Permian Mass Extinction ◽  
Permian Triassic Boundary

Lithium (Li) isotope analyses of sedimentary rocks from the Meishan section in South China reveal extremely light seawater Li isotopic signatures at the Permian–Triassic boundary (PTB), which coincide with the most severe mass extinction in the history of animal life. Using a dynamic seawater lithium box model, we show that the light seawater Li isotopic signatures can be best explained by a significant influx of riverine [Li] with light δ7Li to the ocean realm. The seawater Li isotope excursion started ≥300 Ky before and persisted up to the main extinction event, which is consistent with the eruption time of the Siberian Traps. The eruption of the Siberian Traps exposed an enormous amount of fresh basalt and triggered CO2 release, rapid global warming, and acid rains, which in turn led to a rapid enhancement of continental weathering. The enhanced continental weathering delivered excessive nutrients to the oceans that could lead to marine eutrophication, anoxia, acidification, and ecological perturbation, ultimately resulting in the end-Permian mass extinction.

Magnetostratigraphy across the end-Permian mass extinction event from the Meishan sections, southeastern China

Geology ◽  
2021 ◽  
Author(s):  
Min Zhang ◽  
Hua-Feng Qin ◽  
Kuang He ◽  
Yi-Fei Hou ◽  
Quan-Feng Zheng ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Southeastern China ◽  
Triassic Boundary ◽  
Biodiversity Crisis ◽  
Normal Polarity ◽  
Mass Extinction Event ◽  
Geomagnetic Polarity ◽  
Permian Mass Extinction ◽  
Permian Triassic Boundary ◽  
Geomagnetic Polarity Time Scale

The end-Permian mass extinction (EPME) has been recorded as the most severe biodiversity crisis in Earth’s history, although the timing of the marine and terrestrial extinctions remains debatable. We present a new high-resolution magnetostratigraphic succession across the EPME and the Permian-Triassic boundary (PTB) from the Meishan sections in southeastern China, which contain the global boundary stratotype section and point (GSSP) for the base of the Triassic (also the Induan Stage) and the base of the Changhsingian Stage. We identified five normal and five reverse magnetozones, including MS1n to MS5n and MS1r to MS5r, from oldest to youngest, in the Changhsingian and Induan Stages. The Induan Stage was determined to consist of two polarity intervals, where the upper one is reverse (MS5r), and the lower one is normal (MS5n). The Changhsingian Stage is dominated by normal polarity, intercalated with four short-term reverse magnetozones (MS1r to MS4r). Consequently, the PTB and the Wuchiapingian-Changhsingian boundary are clearly located in MS5n and MS1n, respectively. These new magnetostratigraphic results provide a potential reference geomagnetic polarity pattern with which to refine the geomagnetic polarity time scale for the EPME and the Permian-Triassic transition.

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 taxonomic diversity during the end-Permian mass extinction

Paleobiology ◽  
2021 ◽  
pp. 1-16
Author(s):  
Junyu Wan ◽  
William J. Foster ◽  
Li Tian ◽  
Thomas L. Stubbs ◽  
Michael J. Benton ◽  
...  
Keyword(s):  
Mass Extinction ◽  
Microbial Mats ◽  
Benthic Communities ◽  
Ecological Impact ◽  
Taxonomic Diversity ◽  
Morphological Disparity ◽  
Extinction Event ◽  
Permian Extinction ◽  
Permian Mass Extinction ◽  
Marine Platform

Abstract An increasing number of unexpectedly diverse benthic communities are being reported from microbially precipitated carbonate facies in shallow-marine platform settings after the end-Permian mass extinction. Ostracoda, which was one of the most diverse and abundant metazoan groups during this interval, recorded its greatest diversity and abundance associated with these facies. Previous studies, however, focused mainly on taxonomic diversity and, therefore, left room for discussion of paleoecological significance. Here, we apply a morphometric method (semilandmarks) to investigate morphological variance through time to better understand the ecological consequences of the end-Permian mass extinction and to examine the hypothesis that microbial mats played a key role in ostracod survival. Our results show that taxonomic diversity and morphological disparity were decoupled during the end-Permian extinction and that morphological disparity declined rapidly at the onset of the end-Permian extinction, even though the high diversity of ostracods initially survived in some places. The decoupled changes in taxonomic diversity and morphological disparity suggest that the latter is a more robust proxy for understanding the ecological impact of the extinction event, and the low morphological disparity of ostracod faunas is a consequence of sustained environmental stress or a delayed post-Permian radiation. Furthermore, the similar morphological disparity of ostracods between microbialite and non-microbialite facies indicates that microbial mats most likely represent a taphonomic window rather than a biological refuge during the end-Permian extinction interval.

scholarly journals Species richness and disparity of parareptiles across the end-Permian mass extinction

2019 ◽  
Vol 286 (1899) ◽  
pp. 20182572 ◽  
Author(s):  
Mark J. MacDougall ◽  
Neil Brocklehurst ◽  
Jörg Fröbisch
Keyword(s):  
Species Richness ◽  
Mass Extinction ◽  
Morphological Diversity ◽  
Ecological Niches ◽  
Sharp Drop ◽  
Triassic Boundary ◽  
Continuous Increase ◽  
Declining Species ◽  
Permian Mass Extinction ◽  
Extinction Events

The amniote clade Parareptilia is notable in that members of the clade exhibited a wide array of morphologies, were successful in a variety of ecological niches and survived the end-Permian mass extinction. In order to better understand how mass extinction events can affect clades that survive them, we investigate both the species richness and morphological diversity (disparity) of parareptiles over the course of their history. Furthermore, we examine our observations in the context of other metazoan clades, in order to identify post-extinction survivorship patterns that are present in the clade. The results of our study indicate that there was an early increase in parareptilian disparity, which then fluctuated over the course of the Permian, before it eventually declined sharply towards the end of the Permian and into the Triassic, corresponding with the end-Permian mass extinction event. Interestingly, this is a different trend to what is observed regarding parareptile richness, that shows an almost continuous increase until its overall peak at the end of the Late Permian. Moreover, richness did not experience the same sharp drop at the end of the Permian, reaching a plateau until the Anisian, before dropping sharply and remaining low, with the clade going extinct at the end of the Triassic. This observed pattern is likely to be due to the fact that, despite the extinction of several morphologically distinct parareptile clades, the procolophonoids, one of the largest parareptilian clades, were diversifying across the Permian–Triassic boundary. With the clade's low levels of disparity and eventually declining species richness, this pattern most resembles a ‘dead clade walking’ pattern.

Sign in / Sign up

Export Citation Format

Share Document