Daniel A. Stephen’s research while affiliated with Utah Valley University and other places

... Four of the "Big Five" extinctions seem to be followed by greenhouse conditions, presumably accompanied by a broad tropics, although icehouse conditions came relatively soon after the Late Devonian extinction (e.g., Lakin et al. 2016). Many have attributed the apparently slow Early Triassic rebound to prolonged adverse conditions rather than limitations specific to particular clades, but the extreme view that near-equator regions were uninhabitably hot for a substantial block of Early Triassic time (e.g., Sun et al. 2012) is seeming less plausible, and sampling may still be an issue: (1) ectothermic vertebrates are increasingly described from the Early Triassic tropics (e.g., Romano et al. 2016Romano et al. , 2020Dai et al. 2023;Jiang et al. 2023); (2) analyses using simulations and a variety of extinction-intensity metrics to evaluate potential sampling effects in the Permo-Triassic interval find no robust evidence for latitudinal variation in extinction intensity in the mass extinction or its (disputed) Guadalupian precursor (Allen et al. 2023); and (3) the rebound lag may be spatially more heterogeneous than generally thought (e.g., Smith et al. 2021;Foster et al. 2022). Unstable Early Triassic climates seem to be more likely than prolonged superheating (e.g., Romano et al. 2013;Goudemand et al. 2019); early views that abiotic instability may play a major, direct or indirect, role in diversity trends (Valentine 1971(Valentine , 1973 should probably be revisited. ...

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Mass extinctions and their rebounds: a macroevolutionary framework

... In the SFB, a transgression that corresponds to the second 3rd order T-R (transgressive-regressive) sequence of the Smithian is recorded (Haq et al., 1987;Embry, 1997), which was controlled by regional tectonics and climate (Olivier et al., 2014;Caravaca et al., 2018;Brayard et al., 2020). Calibrations of late Smithian to early Spathian sedimentary sections within the basin are based on ammonoid biostratigraphy (Guex et al., 2010;Brayard et al., 2013Brayard et al., , 2021. The late Smithian Anasibirites beds represent the maximum flooding at the scale of the basin (Brayard et al., 2013(Brayard et al., , 2020. ...

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Pyrite iron isotope compositions track local sedimentation conditions through the Smithian-Spathian transition (Early Triassic, Utah, USA)

... The Early Triassic sea-level rise resulted in a sedimentary succession exhibiting continental terrigenous conglomerates and sandstones of the Moenkopi Group on the south and eastern sides of the basin, interfingering with marine carbonates of the Thaynes Group towards the north and western sides (Paull and Paull, 1993;Lucas et al., 2007;Brayard et al., 2013). In the SFB, a transgression that corresponds to the second 3rd order T-R (transgressive-regressive) sequence of the Smithian is recorded (Haq et al., 1987;Embry, 1997), which was controlled by regional tectonics and climate (Olivier et al., 2014;Caravaca et al., 2018;Brayard et al., 2020). Calibrations of late Smithian to early Spathian sedimentary sections within the basin are based on ammonoid biostratigraphy (Guex et al., 2010;Brayard et al., 2013Brayard et al., , 2021. ...

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Pyrite iron isotope compositions track local sedimentation conditions through the Smithian-Spathian transition (Early Triassic, Utah, USA)

... REE (Y, Nd) and Sr are enriched in the phosphatized soft tissue of decapod shrimp from the Upper Cretaceous Djebel Oum Tkout Lagerstätte (Gueriau et al., 2014). The REE element Y is concentrated in the phosphatized gut tract of penaeoid shrimp from the Triassic Paris Biota (Brayard et al., 2019). A comparison of modern and Miocene gastropods, echinoderms, and bivalves concluded that significant concentrations of REE elements are a diagenetic signal (MacFadden et al., 2015). ...

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Preservation and diagenesis of soft-bodied fossils and the occurrence of phosphate-associated rare earth elements in the Cambrian (Wuliuan) Spence Shale Lagerstätte

... What's more, detailed conodont or ammonoid biostratigraphic studies have also been reported from the Paris biota and the Chaohu fauna, which makes their biostratigraphy comparable (Brayard et al., 2017(Brayard et al., , 2019Zhao et al., 2007Zhao et al., , 2008. Here, we present a unique late Early Triassic conodont community from the Zhangjiawan section, Yuan'an County, Hubei Province. ...

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A unique early Triassic (Spathian) conodont community from the Nanzhang‐Yuan 'an Fauna, Hubei Province, South China

... assemblage documenting an unexpectedly rapid post-Permian recovery of some marine groups and complex marine ecosystems (Brayard et al., 2017;Doguzhaeva et al., 2018;Botting et al., 2019;Brayard et al., 2019b;Charbonnier et al., 2019;Iniesto et al., 2019;Romano et al., 2019;Saucè de et al., 2019). The new ophiuroid allows elucidating at least a small part of the insufficiently known Triassic ophiuroid fossil record. ...

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A new brittle star (Ophiuroidea: Ophiodermatina) from the Early Triassic Paris Biota (Bear Lake County, Idaho, USA).

... Sedimentary biological pyrite sulfur isotope ratios (δ 34 S py ) have been extensively employed to study ancient oceanic and basinal sulfur cycles (e.g., Paytan et al., 2004;Hurtgen et al., 2005Hurtgen et al., , 2009; Thompson and Kah, 2012;Song et al., 2014;Algeo et al., 2015;Fike et al., 2015;Kah et al., 2016;Shi et al., 2018;Stebbins et al., 2019a;Thomazo et al., 2019). Variations in bulk sedimentary δ 34 S py signatures have been plausibly linked to oceanic sulfur cycle perturbations (e.g., Hurtgen et al., 2009;Gill et al., 2011;Halevy et al., 2012;Algeo et al., 2015;Sim et al., 2015;Schobben et al., 2017;Stebbins et al., 2019a,b;Young et al., 2020) or basin isolation effect (Gomes and Hurtgen, 2013;Kurzweil et al., 2015;Paiste et al., 2020). ...

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Variability of sedimentary pyrite δ34S records: A case study of slope shale of the Green Point Formation in western Newfoundland, Canada

... Mn, V, U, Mo, Mo/Al ratio), iron speciation and size of framboidal pyrite suggest occurrences of transient anoxia in the water column that could have spread onto continental shelves (Grasby et al., 2013;Song et al., 2013;Zhang et al., 2015;Elrick et al., 2017;Song et al., 2019;Zhang et al., 2019). Although anoxic and/ or euxinic conditions seem to be recurrent in the Early Triassic deep ocean, well-oxygenated shallow-marine environments, as well as diversified and complex ecosystems are also documented (Beatty et al., 2008;Hautmann et al., 2011;Collin et al., 2015;Brayard et al., 2017;Olivier et al., 2018;Smith et al., 2021;Dai et al., 2023). Reconstructing the redox state of the water column together with the sediment porewaters is therefore key to better understand the evolution of the environmental conditions in space and time that prevailed through the late Smithian and the SSB, and that may have markedly influenced the biotic recovery in the aftermath of the end-Permian mass extinction. ...

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Pyrite iron isotope compositions track local sedimentation conditions through the Smithian-Spathian transition (Early Triassic, Utah, USA)

... This variation has previously been interpreted as resulting from changes in the composition of sedimentary organic matter, rather than secular sea water DIC evolution . Given that this δ 13 C carb decline is not associated with large changes in δ 44/40 Ca or δ 26 Mg values, is not considered a global chemostratigraphic marker, but is associated with a well-known regional early Spathian regression Caravaca et al., 2017;Grosjean et al., 2018), meteoric diagenesis of the carbonate minerals is favoured as an explanation for this pattern. Some dolomite is also present in the Tirolites Limestone, but it is generally less abundant than in Units I-IV ( Figure 2). ...

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Smithian–Spathian carbonate geochemistry in the northern Thaynes Group influenced by multiple styles of diagenesis

... It is overlain by Dienerian red to maroon calcareous siltstones of the Woodside Formation, which in turn is overlain by variably alternating shales and limestones of the Smithian-Spathian Thaynes Group (Kummel, 1943). Collectively, these lithostratigraphic units represent a mixed carbonatesiliciclastic succession, with considerable variations in the genesis, proportion and stoichiometry of carbonate mineralogy within and between lithostratigraphic units (Caravaca et al., 2017). Elsewhere in both the northern and southern subbasins, the Thaynes Group is described with different lithostratigraphic schemes and rests unconformably on Middle to Late Permian rocks with a major sedimentary hiatus corresponding to the Permian-Triassic transition and the Induan Stage (Goodspeed & Lucas, 2007;Lucas et al., 2007). ...

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Smithian–Spathian carbonate geochemistry in the northern Thaynes Group influenced by multiple styles of diagenesis