Ediacaran and Cambrian Index Fossils From Sonora, Mexico

Sour-Tovar, Francisco; Hagadorn, James W.; Huitrón-Rubio, Tomás

doi:10.1111/j.1475-4983.2006.00619.x

Cited by 48 publications

(25 citation statements)

References 28 publications

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“…The present study focuses on the Puerto Blanco Formation (PBF), which has been suggested to include Ediacaran and Cambrian strata (Sour Tovar et al, 2007) with a diverse early Cambrian macrofauna and microfauna McMenamin, 1984;Stewart et al, 1984;Debrenne, 1987;McMenamin, 1987;Debrenne et al, 1989;McMenamin, 1992;McMenamin et al, 1994;McMenamin, 2008). The PBF is underlain by the Neoproterozoic La ; area in the square is magnified in 2.…”

Section: Geological Settingmentioning

confidence: 99%

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Early Cambrian Small Shelly Fossils from northwest Mexico: Biostratigraphic implications for Laurentia

Devaere

Clausen

Sosa-Leon

et al. 2019

Palaeontol Electron

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Section: Geological Settingmentioning

confidence: 99%

“…Studied area. Indicated are the main roads (plain lines), trails (dashed lines) and cerros with Ediacaran/Cambrian succession outcrops, after Stewart et al (1984), McMenamin (1987) and Sour-Tovar et al (2007). 4.…”

Section: Geological Settingmentioning

confidence: 99%

Early Cambrian Small Shelly Fossils from northwest Mexico: Biostratigraphic implications for Laurentia

Devaere

Clausen

Sosa-Leon

et al. 2019

Palaeontol Electron

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“…550-541 Ma) sedimentary successions worldwide (Conway Morris et al, 1990;Sour-Tovar et al, 2007;Gaucher & Germs, 2009;Cortijo et al, 2010;Zhuravlev et al, 2012). 550-541 Ma) sedimentary successions worldwide (Conway Morris et al, 1990;Sour-Tovar et al, 2007;Gaucher & Germs, 2009;Cortijo et al, 2010;Zhuravlev et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

“…One of the earliest animals to have developed a biomineralized carbonate exoskeleton is Cloudina-named after the famed Precambrian paleontologist Preston Cloud and preserved in terminal Ediacaran (ca. 550-541 Ma) sedimentary successions worldwide (Conway Morris et al, 1990;Sour-Tovar et al, 2007;Gaucher & Germs, 2009;Cortijo et al, 2010;Zhuravlev et al, 2012). This animal, which is suggested to be an ancient cnidarian-grade (Grant, 1992;Cortijo et al, 2010) or lophotrochozoan animal (Hua et al, 2005;Zhuravlev et al, 2015), constructed a high-Mg calcitic tubular shell with nested funnels, had an epibenthic lifestyle with its apex attached to the substrate (Grant, 1990;Zhuravlev et al, 2012;Cai et al, 2014), and may have had both sexual and asexual reproductive strategies to aid in its broad ecological dispersal (Cortijo et al, 2015).…”

Section: Introductionmentioning

confidence: 99%

Environmental context for the terminal Ediacaran biomineralization of animals

et al. 2016

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In terminal Ediacaran strata of South China, the onset of calcareous biomineralization is preserved in the paleontological transition from Conotubus to Cloudina in repetitious limestone facies of the Dengying Formation. Both fossils have similar size, funnel-in-funnel construction, and epibenthic lifestyle, but Cloudina is biomineralized, whereas Conotubus is not. To provide environmental context for this evolutionary milestone, we conducted a high-resolution elemental and stable isotope study of the richly fossiliferous Gaojiashan Member. Coincident with the first appearance of Cloudina is a significant positive carbonate carbon isotope excursion (up to +6‰) and an increase in the abundance and (34) S composition of pyrite. In contrast, δ(34) S values of carbonate-associated sulfate remain steady throughout the succession, resulting in anomalously large (>70‰) sulfur isotope fractionations in the lower half of the member. The fractionation trend likely relates to changes in microbial communities, with sulfur disproportionation involved in the lower interval, whereas microbial sulfate reduction was the principal metabolic pathway in the upper. We speculate that the coupled paleontological and biogeochemical anomalies may have coincided with an increase in terrestrial weathering fluxes of sulfate, alkalinity, and nutrients to the depositional basin, which stimulated primary productivity, the spread of an oxygen minimum zone, and the development of euxinic conditions in subtidal and basinal environments. Enhanced production and burial of organic matter is thus directly connected to the carbon isotope anomaly, and likely promoted pyritization as the main taphonomic pathway for Conotubus and other soft-bodied Ediacara biotas. Our studies suggest that the Ediacaran confluence of ecological pressures from predation and environmental pressures from an increase in seawater alkalinity set the stage for an unprecedented geobiological response: the evolutionary novelty of animal biomineralization.

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“…3). The ages of these units are well-constrained through temporal correlations built upon biostratigraphic, chemostratigraphic and radiometric data (Stewart, 1970;Stewart et al, 1984;ChristieBlick and Levy, 1989;Heaman and Grotzinger, 1992;Corsetti and Hagadorn, 2000;Jenkins et al, 2002;Corsetti and Kaufman, 2003;Zhou et al, 2004;Jiang et al, 2007;Sour-Tovar et al, 2007;Loyd et al, 2012b). Fig.…”

Section: Geologic Contextmentioning

confidence: 99%

Evolution of Neoproterozoic Wonoka–Shuram Anomaly-aged carbonates: Evidence from clumped isotope paleothermometry

Loyd

Corsetti

Eagle

et al. 2015

Precambrian Research

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a b s t r a c tThe Wonoka-Shuram Anomaly represents the largest negative carbon isotope excursion recognized in the geologic record and is associated with the emergence and diversification of metazoan life ca. 580 million years ago (Ma). The origin of the anomaly is highly debated, with interpretations ranging from primary to diagenetic, each having unique and potentially transformative implications for early life. Here, we apply carbonate clumped isotope thermometry to three sections expressing the anomaly in order to constrain mineral formation temperatures and thus directly calculate water oxygen isotope compositions (␦ 18 O w ) with which carbonate minerals equilibrated. With ␦ 18 O w known, it is possible to address previous hypotheses for the origin of the anomaly. In each section, precipitation temperatures correlate positively with reconstructed ␦ 18 O w . Previous hypotheses, based on the covariance of ␦ 18 O carb vs. ␦ 13 C carb (uncorrected for temperature effects), suggested a meteoric diagenetic origin for the anomaly. However, reconstructed ␦ 18 O w values do not covary with carbon isotope compositions (␦ 13 C carb ) within anomaly facies. Rather, the oxygen isotope and temperature data are consistent with carbonate recrystallization and equilibration under increasingly rock-buffered conditions. Based on simple modeling and comparison to modern formation fluids, recrystallization may have occurred in an environment far removed from the initial depositional or early diagenetic regime. In addition, although clumped isotope temperatures vary significantly and reach elevated values consistent with burial diagenesis, it is unclear to what degree, if at all, carbon isotope values were reset during recrystallization. Ultimately, these new data indicate that Wonoka-Shuram-aged carbonates experienced equilibration with fluids under increasingly closedsystem conditions. The clumped isotope data do not provide a means to distinguish previous hypotheses outright, but provide additional context for the evaluation of geochemical signatures within these ancient carbonate rocks.

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Ediacaran and Cambrian Index Fossils From Sonora, Mexico

Cited by 48 publications

References 28 publications

Early Cambrian Small Shelly Fossils from northwest Mexico: Biostratigraphic implications for Laurentia

Early Cambrian Small Shelly Fossils from northwest Mexico: Biostratigraphic implications for Laurentia

Environmental context for the terminal Ediacaran biomineralization of animals

Evolution of Neoproterozoic Wonoka–Shuram Anomaly-aged carbonates: Evidence from clumped isotope paleothermometry

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