Dynamics of the Largest Carbon Isotope Excursion During the Early Triassic Biotic Recovery

Widmann, Philipp; Bucher, Hugo; Leu, Marc; Vennemann, Torsten; Bagherpour, Borhan; Schneebeli‐Hermann, Elke; Goudemand, Nicolas; Schaltegger, Urs

doi:10.3389/feart.2020.00196

Cited by 25 publications

(52 citation statements)

References 71 publications

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“…comm. H. Bucher, 2020). The low sea level led to the formation of local silled basins with low O 2 content, as was, for instance, the case in the Nanpanjiang basin in South China (Bagherpour et al, 2017).…”

Section: Griesbachianmentioning

confidence: 90%

“…These data suggest a cooler episode during the early Smithian, followed by a rapid warming leading to peak temperatures during the middle Smithian. The late Smithian, coinciding with the extinction event, was associated with a drop in global temperatures (Goudemand et al, 2019;Widmann et al, 2020).…”

Section: Smithianmentioning

confidence: 99%

“…It is probably the result of extrinsic physical changes, such as the improved oxygenation on the shelves, cooler global temperatures and a change in oceanic chemistry after the Smithian substage (e.g. Zhang et al, 2015;Goudemand et al, 2019;Widmann et al, 2020). The lack of episodes of black shale deposition on shelves during the SBG contrasts with the iterative occurrences of such phases in the Griesbachian-Smithian (Hermann et al, 2011;Ware et al, 2015) and the Pelsonian-Longobardian (e.g.…”

Section: The Spathian-bithynian: a Hiatus Or The Base Between Two Waves?mentioning

confidence: 99%

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A Hiatus Obscures the Early Evolution of Modern Lineages of Bony Fishes

Romano

2021

Front. Earth Sci.

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About half of all vertebrate species today are ray-finned fishes (Actinopterygii), and nearly all of them belong to the Neopterygii (modern ray-fins). The oldest unequivocal neopterygian fossils are known from the Early Triassic. They appear during a time when global fish faunas consisted of mostly cosmopolitan taxa, and contemporary bony fishes belonged mainly to non-neopterygian (“paleopterygian”) lineages. In the Middle Triassic (Pelsonian substage and later), less than 10 myrs (million years) after the Permian-Triassic boundary mass extinction event (PTBME), neopterygians were already species-rich and trophically diverse, and bony fish faunas were more regionally differentiated compared to the Early Triassic. Still little is known about the early evolution of neopterygians leading up to this first diversity peak. A major factor limiting our understanding of this “Triassic revolution” is an interval marked by a very poor fossil record, overlapping with the Spathian (late Olenekian, Early Triassic), Aegean (Early Anisian, Middle Triassic), and Bithynian (early Middle Anisian) substages. Here, I review the fossil record of Early and Middle Triassic marine bony fishes (Actinistia and Actinopterygii) at the substage-level in order to evaluate the impact of this hiatus–named herein the Spathian–Bithynian gap (SBG)–on our understanding of their diversification after the largest mass extinction event of the past. I propose three hypotheses: 1) the SSBE hypothesis, suggesting that most of the Middle Triassic diversity appeared in the aftermath of the Smithian-Spathian boundary extinction (SSBE; ∼2 myrs after the PTBME), 2) the Pelsonian explosion hypothesis, which states that most of the Middle Triassic ichthyodiversity is the result of a radiation event in the Pelsonian, and 3) the gradual replacement hypothesis, i.e. that the faunal turnover during the SBG was steady and bony fishes were not affected by extinction events subsequent to the PTBME. Based on current knowledge, hypothesis three is favored herein, but further studies are necessary to test alternative hypotheses. In light of the SBG, claims of a protracted diversification of bony fishes after the PTBME should be treated with caution.

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Section: Griesbachianmentioning

confidence: 90%

Section: Smithianmentioning

confidence: 99%

Section: The Spathian-bithynian: a Hiatus Or The Base Between Two Waves?mentioning

confidence: 99%

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A Hiatus Obscures the Early Evolution of Modern Lineages of Bony Fishes

Romano

2021

Front. Earth Sci.

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“…Absolute ages according to Cohen et al, (2013, updated) and Ovtcharova et al (2015). Information about the relative duration of substages come from Nawrocki & Szulc (2000), Götz, Szulc & Feist-Burkhardt (2005), Galfetti et al (2007), Ovtcharova et al (2006) and Widmann et al (2020). Symbols for ecological guilds redrawn after Aberhan (1994).…”

Section: Figure 1 Maximum Species Richness Throughout the Early And Middlementioning

confidence: 99%

The main stage of recovery after the end-Permian mass extinction: taxonomic rediversification and ecologic reorganization of marine level-bottom communities during the Middle Triassic

Friesenbichler

Hautmann

Bucher

2021

PeerJ

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The recovery of marine life from the end-Permian mass extinction event provides a test-case for biodiversification models in general, but few studies have addressed this episode in its full length and ecological context. This study analyses the recovery of marine level-bottom communities from the end-Permian mass extinction event over a period of 15 Ma, with a main focus on the previously neglected main phase during the Middle Triassic. Our analyses are based on faunas from 37 lithological units representing different environmental settings, ranging from lagoons to inner, mid- and outer ramps. Our dataset comprises 1562 species, which belong to 13 higher taxa and 12 ecological guilds. The diversification pattern of most taxa and guilds shows an initial Early Triassic lag phase that is followed by a hyperbolic diversity increase during the Bithynian (early middle Anisian) and became damped later in the Middle Triassic. The hyperbolic diversity increase is not predicted by models that suggest environmental causes for the initial lag phase. We therefore advocate a model in which diversification is primarily driven by the intensity of biotic interactions. Accordingly, the Early Triassic lag phase represents the time when the reduced species richness in the wake of the end-Permian mass extinction was insufficient for stimulating major diversifications, whereas the Anisian main diversification event started when self-accelerating processes became effective and stopped when niche-crowding prevented further diversification. Biotic interactions that might drive this pattern include interspecific competition but also habitat construction, ecosystem engineering and new options for trophic relationships. The latter factors are discussed in the context of the resurgence of large carbonate platforms, which occurred simultaneously with the diversification of benthic communities. These did not only provide new hardground habitats for a variety of epifaunal taxa, but also new options for grazing gastropods that supposedly fed from microalgae growing on dasycladaceans and other macroalgae. Whereas we do not claim that changing environmental conditions were generally unimportant for the recovery of marine level-bottom communities, we note that their actual role can only be assessed when tested against predictions of the biotic model.

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“…2007; Brayard & Bucher 2015; Widmann et al . 2020). The event signified the end of a diversification–extinction cycle that extended throughout the entire Smithian.…”

Section: Figmentioning

confidence: 99%

The middle Smithian (Early Triassic) ammonoid Arctoceras blomstrandi: conch morphology and ornamentation in relation to stratigraphy

Hansen

Bucher

Schneebeli‐Hermann

et al. 2020

Papers in Palaeontology

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The ammonoid genus Arctoceras (Hyatt) occurs across all palaeolatitudes, and is a key genus for middle Smithian biostratigraphical correlations globally. In this study, intraspecific variations in conch morphology, ornamentation and allometry are examined in relation to stratigraphic position. Arctoceras is the most abundant ammonoid genus in the middle Smithian of Svalbard. Originally, seven Arctoceras species were described from Svalbard. Later, as the importance of intraspecific variation was recognized, six of the Arctoceras species from Svalbard were treated as junior synonyms of Arctoceras blomstrandi (Lindstr€ om). Yet, the variations in A. blomstrandi conch morphology remain poorly quantified and the dependence on stratigraphic position, unknown. We quantify the intraspecific variation in conch morphology, ornamentation and allometry in relation to stratigraphy of the Svalbard Arctoceras. The results support the assignment of all Arctoceras morphotypes from Svalbard to a single species A. blomstrandi. The new data allow for an updated species description and open the way for the use in biostratigraphy of the endmember morphology A. blomstrandi var. costatus. We document consistent changes in conch morphology and ornamentation in the studied stratigraphic interval, with a distinct shift towards more evolute and ornate conchs in the top of the interval. The trends in the strength of ornamentation are partly explained by covariation with conch morphology (Buckman's law). The most marked shift in the conch morphology and allometric development of A. blomstrandi coincides with the onset of the positive carbon isotope excursion at the end of the middle Smithian, but pre-dates the mid-late Smithian cooling of the sea surface.

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Dynamics of the Largest Carbon Isotope Excursion During the Early Triassic Biotic Recovery

Cited by 25 publications

References 71 publications

A Hiatus Obscures the Early Evolution of Modern Lineages of Bony Fishes

A Hiatus Obscures the Early Evolution of Modern Lineages of Bony Fishes

The main stage of recovery after the end-Permian mass extinction: taxonomic rediversification and ecologic reorganization of marine level-bottom communities during the Middle Triassic

The middle Smithian (Early Triassic) ammonoid Arctoceras blomstrandi: conch morphology and ornamentation in relation to stratigraphy

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