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 ◽  
...  

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.

2009 ◽  
Vol 83 (5) ◽  
pp. 718-738 ◽  
Author(s):  
Haijun Song ◽  
Jinnan Tong ◽  
Z. Q. Chen ◽  
Hao Yang ◽  
Yongbiao Wang

Newly obtained foraminifer faunas from the Permian-Triassic (P-Tr) transition at the Dajiang and Bianyang sections in the Nanpanjiang Basin, South China, comprise 61 species in 40 genera. They belong to thePalaeofusulina sinensisZone, the youngest Permian foraminifer zone in South China. Quantitative analysis reveals that the last occurrences of more than a half of species (28/54) fall into a 60-cm-interval at the uppermost Changhsingian skeletal packstone unit and thus calibrate the end-Permian extinction to the skeletal packstonecalcimicrobial framestone boundary. About 93% (54/58) of species of the latest Permian assemblage became extinct in the P-Tr crisis. Four major foraminiferal groups, the Miliolida, Fusulinida, Lagenida, and Textulariina, have extinction rates up to 100%, 96%, 92%, and 50%, respectively, and thus experienced selective extinctions. BothHemigordius longusand ?Globivalvulina bulloidestemporarily survived the end-Permian extinction event and extended into the earliest Triassic but became extinct soon after. The post-extinction foraminifer assemblage is characterized by the presence of both disaster taxa and Lazarus taxa. Foraminifer distribution near the P-Tr boundary also reveals that the irregular contact surface at the uppermost Permian may be created by a massive submarine dissolution event, which may be coeval with the end-Permian mass extinction. A new species,Rectostipulina hexamerata,is described here.


PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e7361
Author(s):  
Jeffrey R. Thompson ◽  
Renato Posenato ◽  
David J. Bottjer ◽  
Elizabeth Petsios

The end-Permian mass extinction (∼252 Ma) was responsible for high rates of extinction and evolutionary bottlenecks in a number of animal groups. Echinoids, or sea urchins, were no exception, and the Permian to Triassic represents one of the most significant intervals of time in their macroevolutionary history. The extinction event was responsible for significant turnover, with the Permian–Triassic representing the transition from stem group echinoid-dominated faunas in the Palaeozoic to Mesozoic faunas dominated by crown group echinoids. This turnover is well-known, however, the environmental and taxonomic distribution of echinoids during the latest Permian and Early Triassic is not. Here we report on an echinoid fauna from the Tesero Member, Werfen Formation (latest Permian to Early Triassic) of the Dolomites (northern Italy). The fauna is largely known from disarticulated ossicles, but consists of both stem group taxa, and a new species of crown group echinoid,Eotiaris teseroensisn. sp. That these stem group echinoids were present in the Tesero Member indicates that stem group echinoids did not go extinct in the Dolomites coincident with the onset of extinction, further supporting other recent work indicating that stem group echinoids survived the end-Permian extinction. Furthermore, the presence ofEotiarisacross a number of differing palaeoenvironments in the Early Triassic may have had implications for the survival of cidaroid echinoids during the extinction event.


Author(s):  
Sandra R Schachat ◽  
Conrad C Labandeira

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.


Paleobiology ◽  
2021 ◽  
pp. 1-1
Author(s):  
Junyu Wan ◽  
William J. Foster ◽  
Li Tian ◽  
Thomas L. Stubbs ◽  
Michael J. Benton ◽  
...  

1992 ◽  
Vol 6 ◽  
pp. 136-136
Author(s):  
Alan S. Horowitz ◽  
Joseph F. Pachut

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.


PLoS ONE ◽  
2017 ◽  
Vol 12 (3) ◽  
pp. e0172321 ◽  
Author(s):  
William J. Foster ◽  
Silvia Danise ◽  
Gregory D. Price ◽  
Richard J. Twitchett

Geology ◽  
2004 ◽  
Vol 32 (9) ◽  
pp. 805 ◽  
Author(s):  
R.J. Twitchett ◽  
L. Krystyn ◽  
A. Baud ◽  
J.R. Wheeley ◽  
S. Richoz

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