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Gutarra S, Mitchell EG, Dunn FS, Gibson BM, Racicot RA, Darroch SAF, Rahman IA. Ediacaran marine animal forests and the ventilation of the oceans. Curr Biol 2024; 34:2528-2534.e3. [PMID: 38761801 DOI: 10.1016/j.cub.2024.04.059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 03/18/2024] [Accepted: 04/25/2024] [Indexed: 05/20/2024]
Abstract
The rise of animals across the Ediacaran-Cambrian transition marked a step-change in the history of life, from a microbially dominated world to the complex macroscopic biosphere we see today.1,2,3 While the importance of bioturbation and swimming in altering the structure and function of Earth systems is well established,4,5,6 the influence of epifaunal animals on the hydrodynamics of marine environments is not well understood. Of particular interest are the oldest "marine animal forests,"7 which comprise a diversity of sessile soft-bodied organisms dominated by the fractally branching rangeomorphs.8,9 Typified by fossil assemblages from the Ediacaran of Mistaken Point, Newfoundland,8,10,11 these ancient communities might have played a pivotal role in structuring marine environments, similar to modern ecosystems,7,12,13 but our understanding of how they impacted fluid flow in the water column is limited. Here, we use ecological modeling and computational flow simulations to explore how Ediacaran marine animal forests influenced their surrounding environment. Our results reveal how organism morphology and community structure and composition combined to impact vertical mixing of the surrounding water. We find that Mistaken Point communities were capable of generating high-mixing conditions, thereby likely promoting gas and nutrient transport within the "canopy." This mixing could have served to enhance local-scale oxygen concentrations and redistribute resources like dissolved organic carbon. Our work suggests that Ediacaran marine animal forests may have contributed to the ventilation of the oceans over 560 million years ago, well before the Cambrian explosion of animals.
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Affiliation(s)
| | - Emily G Mitchell
- Department of Zoology, University Museum of Zoology Cambridge, University of Cambridge, Cambridge CB2 3EJ, UK
| | - Frances S Dunn
- Oxford University Museum of Natural History, University of Oxford, Oxford OX1 3PW, UK
| | - Brandt M Gibson
- Department of Chemical and Physical Sciences, University of Toronto Mississauga, Mississauga, ON L5L 1C6, Canada; Department of Earth and Environmental Sciences, Vanderbilt University, Nashville, TN 37240, USA
| | | | | | - Imran A Rahman
- The Natural History Museum, London SW7 5BD, UK; Oxford University Museum of Natural History, University of Oxford, Oxford OX1 3PW, UK.
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2
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Boag TH, Busch JF, Gooley JT, Strauss JV, Sperling EA. Deep-water first occurrences of Ediacara biota prior to the Shuram carbon isotope excursion in the Wernecke Mountains, Yukon, Canada. GEOBIOLOGY 2024; 22:e12597. [PMID: 38700422 DOI: 10.1111/gbi.12597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 02/29/2024] [Accepted: 03/27/2024] [Indexed: 05/05/2024]
Abstract
Ediacara-type macrofossils appear as early as ~575 Ma in deep-water facies of the Drook Formation of the Avalon Peninsula, Newfoundland, and the Nadaleen Formation of Yukon and Northwest Territories, Canada. Our ability to assess whether a deep-water origination of the Ediacara biota is a genuine reflection of evolutionary succession, an artifact of an incomplete stratigraphic record, or a bathymetrically controlled biotope is limited by a lack of geochronological constraints and detailed shelf-to-slope transects of Ediacaran continental margins. The Ediacaran Rackla Group of the Wernecke Mountains, NW Canada, represents an ideal shelf-to-slope depositional system to understand the spatiotemporal and environmental context of Ediacara-type organisms' stratigraphic occurrence. New sedimentological and paleontological data presented herein from the Wernecke Mountains establish a stratigraphic framework relating shelfal strata in the Goz/Corn Creek area to lower slope deposits in the Nadaleen River area. We report new discoveries of numerous Aspidella hold-fast discs, indicative of frondose Ediacara organisms, from deep-water slope deposits of the Nadaleen Formation stratigraphically below the Shuram carbon isotope excursion (CIE) in the Nadaleen River area. Such fossils are notably absent in coeval shallow-water strata in the Goz/Corn Creek region despite appropriate facies for potential preservation. The presence of pre-Shuram CIE Ediacara-type fossils occurring only in deep-water facies within a basin that has equivalent well-preserved shallow-water facies provides the first stratigraphic paleobiological support for a deep-water origination of the Ediacara biota. In contrast, new occurrences of Ediacara-type fossils (including juvenile fronds, Beltanelliformis, Aspidella, annulated tubes, and multiple ichnotaxa) are found above the Shuram CIE in both deep- and shallow-water deposits of the Blueflower Formation. Given existing age constraints on the Shuram CIE, it appears that Ediacaran organisms may have originated in the deeper ocean and lived there for up to ~15 million years before migrating into shelfal environments in the terminal Ediacaran. This indicates unique ecophysiological constraints likely shaped the initial habitat preference and later environmental expansion of the Ediacara biota.
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Affiliation(s)
- Thomas H Boag
- Department of Earth and Planetary Science, Stanford University, Stanford, California, USA
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA
- Department of Geosciences, Princeton University, Princeton, New Jersey, USA
| | - James F Busch
- Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Jared T Gooley
- Alaska Science Center, U.S. Geological Survey, Anchorage, Alaska, USA
| | - Justin V Strauss
- Department of Earth Sciences, Dartmouth College, Hanover, New Hampshire, USA
| | - Erik A Sperling
- Department of Earth and Planetary Science, Stanford University, Stanford, California, USA
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3
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Fan L, Xu B, Chen S, Liu Y, Li F, Xie W, Prabhu A, Zou D, Wan R, Li H, Liu H, Liu Y, Kao SJ, Chen J, Zhu Y, Rinke C, Li M, Zhu M, Zhang C. Gene inversion led to the emergence of brackish archaeal heterotrophs in the aftermath of the Cryogenian Snowball Earth. PNAS NEXUS 2024; 3:pgae057. [PMID: 38380056 PMCID: PMC10877094 DOI: 10.1093/pnasnexus/pgae057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Accepted: 01/31/2024] [Indexed: 02/22/2024]
Abstract
Land-ocean interactions greatly impact the evolution of coastal life on earth. However, the ancient geological forces and genetic mechanisms that shaped evolutionary adaptations and allowed microorganisms to inhabit coastal brackish waters remain largely unexplored. In this study, we infer the evolutionary trajectory of the ubiquitous heterotrophic archaea Poseidoniales (Marine Group II archaea) presently occurring across global aquatic habitats. Our results show that their brackish subgroups had a single origination, dated to over 600 million years ago, through the inversion of the magnesium transport gene corA that conferred osmotic-stress tolerance. The subsequent loss and gain of corA were followed by genome-wide adjustment, characterized by a general two-step mode of selection in microbial speciation. The coastal family of Poseidoniales showed a rapid increase in the evolutionary rate during and in the aftermath of the Cryogenian Snowball Earth (∼700 million years ago), possibly in response to the enhanced phosphorus supply and the rise of algae. Our study highlights the close interplay between genetic changes and ecosystem evolution that boosted microbial diversification in the Neoproterozoic continental margins, where the Cambrian explosion of animals soon followed.
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Affiliation(s)
- Lu Fan
- Shenzhen Key Laboratory of Marine Archaea Geo-Omics, Department of Ocean Science and Engineering, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong 518055, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, Guangdong 511458, China
| | - Bu Xu
- Shenzhen Key Laboratory of Marine Archaea Geo-Omics, Department of Ocean Science and Engineering, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong 518055, China
| | - Songze Chen
- Shenzhen Key Laboratory of Marine Archaea Geo-Omics, Department of Ocean Science and Engineering, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong 518055, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, Guangdong 511458, China
| | - Yang Liu
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong 518060, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong 518060, China
| | - Fuyan Li
- Daniel K. Inouye Center for Microbial Oceanography: Research and Education (C-MORE), University of Hawaii, Honolulu, HI 96822, USA
| | - Wei Xie
- School of Marine Sciences, Sun Yat-sen University, Zhuhai, Guangdong 519082, China
- Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai, Guangdong 519082, China
| | - Apoorva Prabhu
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Dayu Zou
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong 518060, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong 518060, China
| | - Ru Wan
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian 361005, China
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang 310012, China
- State Key Laboratory of Satellite Ocean Environment Dynamics, Hangzhou, Zhejiang 310012, China
| | - Hongliang Li
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang 310012, China
- State Key Laboratory of Satellite Ocean Environment Dynamics, Hangzhou, Zhejiang 310012, China
| | - Haodong Liu
- Shenzhen Key Laboratory of Marine Archaea Geo-Omics, Department of Ocean Science and Engineering, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong 518055, China
| | - Yuhang Liu
- Shenzhen Key Laboratory of Marine Archaea Geo-Omics, Department of Ocean Science and Engineering, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong 518055, China
| | - Shuh-Ji Kao
- State Key Laboratory of Marine Resource Utilization in South China Sea, Hainan University, Haikou, Hainan 570228, China
- State Key Laboratory of Marine Environmental Science, College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian 361005, China
| | - Jianfang Chen
- Key Laboratory of Marine Ecosystem Dynamics, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou, Zhejiang 310012, China
- State Key Laboratory of Satellite Ocean Environment Dynamics, Hangzhou, Zhejiang 310012, China
| | - Yuanqing Zhu
- Shenzhen Key Laboratory of Marine Archaea Geo-Omics, Department of Ocean Science and Engineering, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong 518055, China
- Shanghai Sheshan National Geophysical Observatory, Shanghai Earthquake Agency, Shanghai 200062, China
| | - Christian Rinke
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Meng Li
- Archaeal Biology Center, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong 518060, China
- Shenzhen Key Laboratory of Marine Microbiome Engineering, Institute for Advanced Study, Shenzhen University, Shenzhen, Guangdong 518060, China
| | - Maoyan Zhu
- College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, Jiangsu 210008, China
- Center for Excellence in Life and Paleoenvironment, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing, Jiangsu 210008, China
| | - Chuanlun Zhang
- Shenzhen Key Laboratory of Marine Archaea Geo-Omics, Department of Ocean Science and Engineering, Southern University of Science and Technology (SUSTech), Shenzhen, Guangdong 518055, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, Guangdong 511458, China
- State Key Laboratory of Satellite Ocean Environment Dynamics, Hangzhou, Zhejiang 310012, China
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4
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Mussini G, Dunn FS. Decline and fall of the Ediacarans: late-Neoproterozoic extinctions and the rise of the modern biosphere. Biol Rev Camb Philos Soc 2024; 99:110-130. [PMID: 37667585 DOI: 10.1111/brv.13014] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 08/22/2023] [Accepted: 08/25/2023] [Indexed: 09/06/2023]
Abstract
The end-Neoproterozoic transition marked a gradual but permanent shift between distinct configurations of Earth's biosphere. This interval witnessed the demise of the enigmatic Ediacaran Biota, ushering in the structured trophic webs and disparate animal body plans of Phanerozoic ecosystems. However, little consensus exists on the reality, drivers, and macroevolutionary implications of end-Neoproterozoic extinctions. Here we evaluate potential drivers of late-Neoproterozoic turnover by addressing recent findings on Ediacaran geochronology, the persistence of classical Ediacaran macrobionts into the Cambrian, and the existence of Ediacaran crown-group eumetazoans. Despite renewed interest in the possibility of Phanerozoic-style 'mass extinctions' in the latest Neoproterozoic, our synthesis of the available evidence does not support extinction models based on episodic geochemical triggers, nor does it validate simple ecological interpretations centred on direct competitive displacement. Instead, we argue that the protracted and indirect effects of early bilaterian innovations, including escalations in sediment engineering, predation, and the largely understudied impacts of reef-building, may best account for the temporal structure and possible selectivity of late-Neoproterozoic extinctions. We integrate these processes into a generalised model of early eumetazoan-dominated ecologies, charting the disruption of spatial and temporal isotropy on the Ediacaran benthos as a consequence of diversifying macrofaunal interactions. Given the nature of resource distribution in Ediacaran ecologies, the continuities among Ediacaran and Cambrian faunas, and the convergent origins of ecologically disruptive innovations among bilaterians we suggest that the rise of Phanerozoic-type biotas may have been unstoppable.
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Affiliation(s)
- Giovanni Mussini
- Department of Earth Sciences, Downing Street, University of Cambridge, Cambridge, CB2 3EQ, UK
| | - Frances S Dunn
- Oxford University Museum of Natural History, Parks Road, University of Oxford, Oxford, OX1 3PW, UK
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5
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Jin Z, Wang X, Wang H, Ye Y, Zhang S. Organic carbon cycling and black shale deposition: an Earth System Science perspective. Natl Sci Rev 2023; 10:nwad243. [PMID: 37900193 PMCID: PMC10612131 DOI: 10.1093/nsr/nwad243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Revised: 08/15/2023] [Accepted: 08/27/2023] [Indexed: 10/31/2023] Open
Abstract
Earth has a prolonged history characterized by substantial cycling of matter and energy between multiple spheres. The production of organic carbon can be traced back to as early as ∼4.0 Ga, but the frequency and scale of organic-rich shales have varied markedly over geological time. In this paper, we discuss the organic carbon cycle and the development of black shale from the perspective of Earth System Science. We propose that black shale depositions are the results of interactions among lithospheric evolution, orbital forcing, weathering, photosynthesis and degradation. Black shales can record Earth's oxygenation process, provide petroleum and metallic mineral resources and reveal information about the driver, direction and magnitude of climate change. Future research on black shales should be expanded to encompass a more extensive and more multidimensional perspective.
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Affiliation(s)
- Zhijun Jin
- Institute of Energy, Peking University, Beijing100871, China
| | - Xiaomei Wang
- Key Laboratory of Petroleum Geochemistry, Central Laboratory of Geological Sciences, Research Institute of Petroleum Exploration and Development, China National Petroleum Corporation, Beijing100083, China
| | - Huajian Wang
- Key Laboratory of Petroleum Geochemistry, Central Laboratory of Geological Sciences, Research Institute of Petroleum Exploration and Development, China National Petroleum Corporation, Beijing100083, China
| | - Yuntao Ye
- Key Laboratory of Petroleum Geochemistry, Central Laboratory of Geological Sciences, Research Institute of Petroleum Exploration and Development, China National Petroleum Corporation, Beijing100083, China
- Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, School of Earth and Space Sciences, Peking University, Beijing100871, China
| | - Shuichang Zhang
- Key Laboratory of Petroleum Geochemistry, Central Laboratory of Geological Sciences, Research Institute of Petroleum Exploration and Development, China National Petroleum Corporation, Beijing100083, China
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6
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Ostrander CM, Bjerrum CJ, Ahm ASC, Stenger SR, Bergmann KD, El-Ghali MAK, Harthi AR, Aisri Z, Nielsen SG. Widespread seafloor anoxia during generation of the Ediacaran Shuram carbon isotope excursion. GEOBIOLOGY 2023; 21:556-570. [PMID: 37157927 DOI: 10.1111/gbi.12557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2022] [Revised: 04/13/2023] [Accepted: 04/25/2023] [Indexed: 05/10/2023]
Abstract
Reconstructing the oxygenation history of Earth's oceans during the Ediacaran period (635 to 539 million years ago) has been challenging, and this has led to a polarizing debate about the environmental conditions that played host to the rise of animals. One focal point of this debate is the largest negative inorganic C-isotope excursion recognized in the geologic record, the Shuram excursion, and whether this relic tracks the global-scale oxygenation of Earth's deep oceans. To help inform this debate, we conducted a detailed geochemical investigation of two siliciclastic-dominated successions from Oman deposited through the Shuram Formation. Iron speciation data from both successions indicate formation beneath an intermittently anoxic local water column. Authigenic thallium (Tl) isotopic compositions leached from both successions are indistinguishable from bulk upper continental crust (ε205 TlA ≈ -2) and, by analogy with modern equivalents, likely representative of the ancient seawater ε205 Tl value. A crustal seawater ε205 Tl value requires limited manganese (Mn) oxide burial on the ancient seafloor, and by extension widely distributed anoxic sediment porewaters. This inference is supported by muted redox-sensitive element enrichments (V, Mo, and U) and consistent with some combination of widespread (a) bottom water anoxia and (b) high sedimentary organic matter loading. Contrary to a classical hypothesis, our interpretations place the Shuram excursion, and any coeval animal evolutionary events, in a predominantly anoxic global ocean.
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Affiliation(s)
- Chadlin M Ostrander
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
- NIRVANA Laboratories, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
- Department of Geology and Geophysics, University of Utah, Salt Lake City, Utah, USA
| | - Christian J Bjerrum
- Department of Geoscience and Natural Resource Management, Nordic Center for Earth Evolution, University of Copenhagen, Copenhagen K, Denmark
| | - Anne-Sofie C Ahm
- Department of Geoscience and Natural Resource Management, Nordic Center for Earth Evolution, University of Copenhagen, Copenhagen K, Denmark
- School of Earth and Ocean Sciences, University of Victoria, Victoria, British Columbia, Canada
| | - Simon R Stenger
- Department of Geoscience and Natural Resource Management, Nordic Center for Earth Evolution, University of Copenhagen, Copenhagen K, Denmark
- Norwegian Geotechnical Institute, Trondheim, Norway
| | - Kristin D Bergmann
- Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Mohamed A K El-Ghali
- Department of Earth Sciences and Earth Sciences Research Centre, Sultan Qaboos University, Muscat, Oman
| | | | | | - Sune G Nielsen
- NIRVANA Laboratories, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
- Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts, USA
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7
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Wang H, Peng Y, Li C, Cao X, Cheng M, Bao H. Sulfate triple-oxygen-isotope evidence confirming oceanic oxygenation 570 million years ago. Nat Commun 2023; 14:4315. [PMID: 37463883 DOI: 10.1038/s41467-023-39962-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2023] [Accepted: 07/05/2023] [Indexed: 07/20/2023] Open
Abstract
The largest negative inorganic carbon isotope excursion in Earth's history, namely the Ediacaran Shuram Excursion (SE), closely followed by early animal radiation, has been widely interpreted as a consequence of oceanic oxidation. However, the primary nature of the signature, source of oxidants, and tempo of the event remain contested. Here, we show that carbonate-associated sulfate (CAS) from three different paleocontinents all have conspicuous negative 17O anomalies (Δ'17OCAS values down to -0.53‰) during the SE. Furthermore, the Δ'17OCAS varies in correlation with its corresponding δ34SCAS and δ18OCAS as well as the carbonate δ13Ccarb, decreasing initially followed by a recovery over the ~7-Myr SE duration. In a box-model examination, we argue for a period of sustained water-column ventilation and consequently enhanced sulfur oxidation in the SE ocean. Our findings reveal a direct involvement of mass-anomalously 17O-depleted atmospheric O2 in marine sulfate formation and thus a primary global oceanic oxygenation event during the SE.
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Affiliation(s)
- Haiyang Wang
- International Center for Isotope Effects Research, Nanjing University, Nanjing, China
- State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation & Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, China
- International Center for Sedimentary Geochemistry and Biogeochemistry Research, Chengdu University of Technology, Chengdu, China
| | - Yongbo Peng
- International Center for Isotope Effects Research, Nanjing University, Nanjing, China.
- Frontiers Science Center for Critical Earth Material Cycling and State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China.
| | - Chao Li
- State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation & Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, China.
- International Center for Sedimentary Geochemistry and Biogeochemistry Research, Chengdu University of Technology, Chengdu, China.
- Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications of Ministry of Natural Resources, Chengdu University of Technology, Chengdu, China.
| | - Xiaobin Cao
- International Center for Isotope Effects Research, Nanjing University, Nanjing, China
- Frontiers Science Center for Critical Earth Material Cycling and State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
| | - Meng Cheng
- State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation & Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, China
- International Center for Sedimentary Geochemistry and Biogeochemistry Research, Chengdu University of Technology, Chengdu, China
- Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications of Ministry of Natural Resources, Chengdu University of Technology, Chengdu, China
| | - Huiming Bao
- International Center for Isotope Effects Research, Nanjing University, Nanjing, China.
- Frontiers Science Center for Critical Earth Material Cycling and State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing, China.
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8
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Zheng W, Zhou A, Sahoo SK, Nolan MR, Ostrander CM, Sun R, Anbar AD, Xiao S, Chen J. Recurrent photic zone euxinia limited ocean oxygenation and animal evolution during the Ediacaran. Nat Commun 2023; 14:3920. [PMID: 37400445 DOI: 10.1038/s41467-023-39427-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Accepted: 06/12/2023] [Indexed: 07/05/2023] Open
Abstract
The Ediacaran Period (~635-539 Ma) is marked by the emergence and diversification of complex metazoans linked to ocean redox changes, but the processes and mechanism of the redox evolution in the Ediacaran ocean are intensely debated. Here we use mercury isotope compositions from multiple black shale sections of the Doushantuo Formation in South China to reconstruct Ediacaran oceanic redox conditions. Mercury isotopes show compelling evidence for recurrent and spatially dynamic photic zone euxinia (PZE) on the continental margin of South China during time intervals coincident with previously identified ocean oxygenation events. We suggest that PZE was driven by increased availability of sulfate and nutrients from a transiently oxygenated ocean, but PZE may have also initiated negative feedbacks that inhibited oxygen production by promoting anoxygenic photosynthesis and limiting the habitable space for eukaryotes, hence abating the long-term rise of oxygen and restricting the Ediacaran expansion of macroscopic oxygen-demanding animals.
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Affiliation(s)
- Wang Zheng
- School of Earth System Science, Institute of Surface-Earth System Science, Tianjin University, Tianjin, 300072, China
| | - Anwen Zhou
- School of Earth System Science, Institute of Surface-Earth System Science, Tianjin University, Tianjin, 300072, China
- Department of Earth, Ocean and Atmospheric Science and National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32306, USA
| | | | - Morrison R Nolan
- Department of Geosciences, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Chadlin M Ostrander
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, 02543, USA
- Department of Geology and Geophysics, University of Utah, Salt Lake City, UT, 84112, USA
| | - Ruoyu Sun
- School of Earth System Science, Institute of Surface-Earth System Science, Tianjin University, Tianjin, 300072, China
| | - Ariel D Anbar
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, 85287, USA
- School of Molecular Sciences, Arizona State University, Tempe, AZ, 85287, USA
| | - Shuhai Xiao
- Department of Geosciences, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Jiubin Chen
- School of Earth System Science, Institute of Surface-Earth System Science, Tianjin University, Tianjin, 300072, China.
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9
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Gong Z, Wei GY, Fakhraee M, Alcott LJ, Jiang L, Zhao M, Planavsky NJ. Revisiting marine redox conditions during the Ediacaran Shuram carbon isotope excursion. GEOBIOLOGY 2023; 21:407-420. [PMID: 36755479 DOI: 10.1111/gbi.12547] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2022] [Revised: 12/18/2022] [Accepted: 01/27/2023] [Indexed: 06/13/2023]
Abstract
The Neoproterozoic carbonate record contains multiple carbon isotope anomalies, which are the subject of intense debate. The largest of these anomalies, the Shuram excursion (SE), occurred in the mid-Ediacaran (~574-567 Ma). Accurately reconstructing marine redox landscape is a clear path toward making sense of the mechanism that drives this δ13 C anomaly. Here, we report new uranium isotopic data from the shallow-marine carbonates of the Wonoka Formation, Flinders Ranges, South Australia, where the SE is well preserved. Our data indicate that the δ238 U trend during the SE is highly reproducible across globally disparate sections from different depositional settings. Previously, it was proposed that the positive shift of δ238 U values during the SE suggests an extensive, near-modern level of marine oxygenation. However, recent publications suggest that the fractionation of uranium isotopes in ferruginous and anoxic conditions is comparable, opening up the possibility of non-unique interpretations of the carbonate uranium isotopic record. Here, we build on this idea by investigating the SE in conjunction with additional geochemical proxies. Using a revised uranium isotope mass balance model and an inverse stochastic carbon cycle model, we reevaluate models for δ13 C and δ238 U trends during the SE. We suggest that global seawater δ238 U values during the SE could be explained by an expansion of ferruginous conditions and do not require a near-modern level of oxygenation during the mid-Ediacaran.
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Affiliation(s)
- Zheng Gong
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA
| | - Guang-Yi Wei
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA
- School of Earth Sciences and Engineering, Nanjing University, Nanjing, China
| | - Mojtaba Fakhraee
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA
| | - Lewis J Alcott
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA
| | - Lei Jiang
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA
- Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
| | - Mingyu Zhao
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA
- Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing, China
| | - Noah J Planavsky
- Department of Earth and Planetary Sciences, Yale University, New Haven, Connecticut, USA
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10
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Dodd MS, Shi W, Li C, Zhang Z, Cheng M, Gu H, Hardisty DS, Loyd SJ, Wallace MW, vS Hood A, Lamothe K, Mills BJW, Poulton SW, Lyons TW. Uncovering the Ediacaran phosphorus cycle. Nature 2023:10.1038/s41586-023-06077-6. [PMID: 37258677 DOI: 10.1038/s41586-023-06077-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2022] [Accepted: 04/12/2023] [Indexed: 06/02/2023]
Abstract
Phosphorus is a limiting nutrient that is thought to control oceanic oxygen levels to a large extent1-3. A possible increase in marine phosphorus concentrations during the Ediacaran Period (about 635-539 million years ago) has been proposed as a driver for increasing oxygen levels4-6. However, little is known about the nature and evolution of phosphorus cycling during this time4. Here we use carbonate-associated phosphate (CAP) from six globally distributed sections to reconstruct oceanic phosphorus concentrations during a large negative carbon-isotope excursion-the Shuram excursion (SE)-which co-occurred with global oceanic oxygenation7-9. Our data suggest pulsed increases in oceanic phosphorus concentrations during the falling and rising limbs of the SE. Using a quantitative biogeochemical model, we propose that this observation could be explained by carbon dioxide and phosphorus release from marine organic-matter oxidation primarily by sulfate, with further phosphorus release from carbon-dioxide-driven weathering on land. Collectively, this may have resulted in elevated organic-pyrite burial and ocean oxygenation. Our CAP data also seem to suggest equivalent oceanic phosphorus concentrations under maximum and minimum extents of ocean anoxia across the SE. This observation may reflect decoupled phosphorus and ocean anoxia cycles, as opposed to their coupled nature in the modern ocean. Our findings point to external stimuli such as sulfate weathering rather than internal oceanic phosphorus-oxygen cycling alone as a possible control on oceanic oxygenation in the Ediacaran. In turn, this may help explain the prolonged rise of atmospheric oxygen levels.
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Affiliation(s)
- Matthew S Dodd
- State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, China
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
- International Center for Sedimentary Geochemistry and Biogeochemistry Research, Chengdu University of Technology, Chengdu, China
- School of Earth Sciences, University of Western Australia, Perth, Western Australia, Australia
- Forrest Research Foundation, Perth, Western Australia, Australia
| | - Wei Shi
- State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, China
- International Center for Sedimentary Geochemistry and Biogeochemistry Research, Chengdu University of Technology, Chengdu, China
| | - Chao Li
- State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, China.
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China.
- International Center for Sedimentary Geochemistry and Biogeochemistry Research, Chengdu University of Technology, Chengdu, China.
| | - Zihu Zhang
- State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, China
- International Center for Sedimentary Geochemistry and Biogeochemistry Research, Chengdu University of Technology, Chengdu, China
| | - Meng Cheng
- State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu, China
- International Center for Sedimentary Geochemistry and Biogeochemistry Research, Chengdu University of Technology, Chengdu, China
| | - Haodong Gu
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, China
| | - Dalton S Hardisty
- Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, USA
| | - Sean J Loyd
- Department of Geological Sciences, California State University, Fullerton, CA, USA
| | - Malcolm W Wallace
- School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Ashleigh vS Hood
- School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Kelsey Lamothe
- School of Geography, Earth and Atmospheric Sciences, University of Melbourne, Parkville, Victoria, Australia
| | | | - Simon W Poulton
- School of Earth and Environment, University of Leeds, Leeds, UK
| | - Timothy W Lyons
- Department of Earth and Planetary Sciences, University of California, Riverside, Riverside, CA, USA
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11
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A diverse Ediacara assemblage survived under low-oxygen conditions. Nat Commun 2022; 13:7306. [PMID: 36435820 PMCID: PMC9701187 DOI: 10.1038/s41467-022-35012-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 11/15/2022] [Indexed: 11/28/2022] Open
Abstract
The Ediacaran biota were soft-bodied organisms, many with enigmatic phylogenetic placement and ecology, living in marine environments between 574 and 539 million years ago. Some studies hypothesize a metazoan affinity and aerobic metabolism for these taxa, whereas others propose a fundamentally separate taxonomic grouping and a reliance on chemoautotrophy. To distinguish between these hypotheses and test the redox-sensitivity of Ediacaran organisms, here we present a high-resolution local and global redox dataset from carbonates that contain in situ Ediacaran fossils from Siberia. Cerium anomalies are consistently >1, indicating that local environments, where a diverse Ediacaran assemblage is preserved in situ as nodules and carbonaceous compressions, were pervasively anoxic. Additionally, δ238U values match other terminal Ediacaran sections, indicating widespread marine euxinia. These data suggest that some Ediacaran biotas were tolerant of at least intermittent anoxia, and thus had the capacity for a facultatively anaerobic lifestyle. Alternatively, these soft-bodied Ediacara organisms may have colonized the seafloor during brief oxygenation events not recorded by redox proxy data. Broad temporal correlations between carbon, sulfur, and uranium isotopes further highlight the dynamic redox landscape of Ediacaran-Cambrian evolutionary events.
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12
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Affiliation(s)
- Huan Cui
- Equipe Géomicrobiologie, Institut de Physique du Globe de Paris (IPGP), Université de Paris, Paris 75005, France; Stable Isotope Laboratory and CIFAR Earth 4D Group, Department of Earth Sciences, University of Toronto, Toronto, ON M5S 3B1, Canada.
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13
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Li C, Shi W, Cheng M, Jin C, Algeo TJ. The redox structure of Ediacaran and early Cambrian oceans and its controls. Sci Bull (Beijing) 2020; 65:2141-2149. [PMID: 36732967 DOI: 10.1016/j.scib.2020.09.023] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2020] [Revised: 08/24/2020] [Accepted: 08/25/2020] [Indexed: 02/04/2023]
Abstract
The rapid diversification of early animals during the Ediacaran (635-541 Ma) and early Cambrian (ca. 541-509 Ma) has frequently been attributed to increasing oceanic oxygenation. However, the pattern of oceanic oxygenation and its relationship to early animal evolution remain in debate. In this review, we examine the redox structure of Ediacaran and early Cambrian oceans and its controls, offering new insights into contemporaneous oceanic oxygenation patterns and their role in the coevolution of environments and early animals. We review the development of marine redox models which, in combination with independent distal deep-ocean redox proxies, supports a highly redox-stratified shelf and an anoxia-dominated deep ocean during the Ediacaran and early Cambrian. Geochemical and modeling evidence indicates that the marine redox structure was likely controlled by low atmospheric O2 levels and low seawater vertical mixing rates on shelves at that time. Furthermore, theoretical analysis and increasing geochemical evidence, particularly from South China, show that limited sulfate availability was a primary control on the attenuation of mid-depth euxinia offshore, in contrast to the existing paradigm invoking decreased organic carbon fluxes distally. In light of our review, we infer that if oceanic oxygenation indeed triggered the rise of early animals, it must have done so through a shelf oxygenation which was probably driven by elevated oxidant availability. Our review calls for further studies on Ediacaran-Cambrian marine redox structure and its controls, particularly from regions outside of South China, in order to better understand the coevolutionary relationship between oceanic redox and early animals.
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Affiliation(s)
- Chao Li
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China.
| | - Wei Shi
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China
| | - Meng Cheng
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China
| | - Chengsheng Jin
- Yunnan Key Laboratory for Palaeobiology, Yunnan University, Kunming 650091, China
| | - Thomas J Algeo
- State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China; State Key Laboratory of Geological Process and Mineral Resources, China University of Geosciences, Wuhan 430074, China; Department of Geology, University of Cincinnati, Cincinnati OH45221, USA
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14
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Abstract
The rise of animals occurred during an interval of Earth history that witnessed dynamic marine redox conditions, potentially rapid plate motions, and uniquely large perturbations to global biogeochemical cycles. The largest of these perturbations, the Shuram carbon isotope excursion, has been invoked as a driving mechanism for Ediacaran environmental change, possibly linked with evolutionary innovation or extinction. However, there are a number of controversies surrounding the Shuram, including its timing, duration, and role in the concomitant biological and biogeochemical upheavals. Here we present radioisotopic dates bracketing the Shuram on two separate paleocontinents; our results are consistent with a global and synchronous event between 574.0 ± 4.7 and 567.3 ± 3.0 Ma. These dates support the interpretation that the Shuram is a primary and synchronous event postdating the Gaskiers glaciation. In addition, our Re-Os ages suggest that the appearance of Ediacaran macrofossils in northwestern Canada is identical, within uncertainty, to similar macrofossils from the Conception Group of Newfoundland, highlighting the coeval appearance of macroscopic metazoans across two paleocontinents. Our temporal framework for the terminal Proterozoic is a critical step for testing hypotheses related to extreme carbon isotope excursions and their role in the evolution of complex life.
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15
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Fan H, Nielsen SG, Owens JD, Auro M, Shu Y, Hardisty DS, Horner TJ, Bowman CN, Young SA, Wen H. Constraining oceanic oxygenation during the Shuram excursion in South China using thallium isotopes. GEOBIOLOGY 2020; 18:348-365. [PMID: 32011800 DOI: 10.1111/gbi.12379] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Revised: 11/23/2019] [Accepted: 01/14/2020] [Indexed: 06/10/2023]
Abstract
Ediacaran sediments record an unusual global carbon cycle perturbation that has been linked to widespread oceanic oxygenation, the Shuram negative C isotope excursion (NCIE). However, proxy-based estimates of global ocean redox conditions during this event have been limited largely due to proxy specificity (e.g., euxinic sediments for Mo and U isotopes). Modern global seawater documents a homogenous Tl isotope composition (ε205 Tl = -6.0) due to significant manganese oxide burial, which is recorded in modern euxinic sediments. Here, we provide new data documenting that sediments deposited beneath reducing but a non-sulfidic water column from the Santa Barbara Basin (ε205 Tl = -5.6 ± 0.1) also faithfully capture global seawater Tl isotope values. Thus, the proxy utilization of Tl isotopes can extend beyond strictly euxinic settings. Second, to better constrain the global redox conditions during the Shuram NCIE, we measured Tl isotopes of locally euxinic and ferruginous shales of the upper Doushantuo Formation, South China. The ε205 Tl values of these shales exhibit a decreasing trend from ≈-3 to ≈-8, broadly coinciding with the onset of Shuram NCIE. There are ε205 Tl values (-5.1 to -7.8) during the main Shuram NCIE interval that approach values more negative than modern global seawater. These results suggest that manganese oxide burial was near or even greater than modern burial fluxes, which is likely linked to an expansion of oxic conditions. This ocean oxygenation may have been an important trigger for the Shuram NCIE and evolution of Ediacaran-type biota. Subsequently, Tl isotopes show an increasing trend from the modern ocean value to values near the modern global inputs or even heavier (ε205 Tl ≈ -2.5 ~ 0.4), occurring prior to recovery from the NCIE. These records may suggest that there was a decrease in the extent of oxygenated conditions in the global oceans during the late stage of the Shuram NCIE.
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Affiliation(s)
- Haifeng Fan
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Sune G Nielsen
- NIRVANA Laboratories, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- Department of Geology & Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Jeremy D Owens
- Department of Earth, Ocean and Atmospheric Science, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - Maureen Auro
- NIRVANA Laboratories, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Yunchao Shu
- NIRVANA Laboratories, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Dalton S Hardisty
- Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, USA
| | - Tristan J Horner
- NIRVANA Laboratories, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
- Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
| | - Chelsie N Bowman
- Department of Earth, Ocean and Atmospheric Science, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - Seth A Young
- Department of Earth, Ocean and Atmospheric Science, National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - Hanjie Wen
- State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
- University of Chinese Academy of Sciences, Beijing, China
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16
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Cole DB, Mills DB, Erwin DH, Sperling EA, Porter SM, Reinhard CT, Planavsky NJ. On the co-evolution of surface oxygen levels and animals. GEOBIOLOGY 2020; 18:260-281. [PMID: 32175670 DOI: 10.1111/gbi.12382] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2019] [Revised: 01/04/2020] [Accepted: 01/22/2020] [Indexed: 05/22/2023]
Abstract
Few topics in geobiology have been as extensively debated as the role of Earth's oxygenation in controlling when and why animals emerged and diversified. All currently described animals require oxygen for at least a portion of their life cycle. Therefore, the transition to an oxygenated planet was a prerequisite for the emergence of animals. Yet, our understanding of Earth's oxygenation and the environmental requirements of animal habitability and ecological success is currently limited; estimates for the timing of the appearance of environments sufficiently oxygenated to support ecologically stable populations of animals span a wide range, from billions of years to only a few million years before animals appear in the fossil record. In this light, the extent to which oxygen played an important role in controlling when animals appeared remains a topic of debate. When animals originated and when they diversified are separate questions, meaning either one or both of these phenomena could have been decoupled from oxygenation. Here, we present views from across this interpretive spectrum-in a point-counterpoint format-regarding crucial aspects of the potential links between animals and surface oxygen levels. We highlight areas where the standard discourse on this topic requires a change of course and note that several traditional arguments in this "life versus environment" debate are poorly founded. We also identify a clear need for basic research across a range of fields to disentangle the relationships between oxygen availability and emergence and diversification of animal life.
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Affiliation(s)
- Devon B Cole
- School of Earth and Atmospheric Science, Georgia Institute of Technology, Atlanta, Georgia
| | - Daniel B Mills
- Department of Geological Sciences, Stanford University, Stanford, California
| | - Douglas H Erwin
- Department of Paleobiology, National Museum of Natural History, Washington, District of Columbia
- Santa Fe Institute, Santa Fe, New Mexico
| | - Erik A Sperling
- Department of Geological Sciences, Stanford University, Stanford, California
| | - Susannah M Porter
- Department of Earth Science, University of California Santa Barbara, Santa Barbara, California
| | - Christopher T Reinhard
- School of Earth and Atmospheric Science, Georgia Institute of Technology, Atlanta, Georgia
| | - Noah J Planavsky
- Department of Geology and Geophysics, Yale University, New Haven, Connecticut
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17
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Bowyer FT, Shore AJ, Wood RA, Alcott LJ, Thomas AL, Butler IB, Curtis A, Hainanan S, Curtis-Walcott S, Penny AM, Poulton SW. Regional nutrient decrease drove redox stabilisation and metazoan diversification in the late Ediacaran Nama Group, Namibia. Sci Rep 2020; 10:2240. [PMID: 32042140 PMCID: PMC7010733 DOI: 10.1038/s41598-020-59335-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 12/30/2019] [Indexed: 12/01/2022] Open
Abstract
The late Ediacaran witnessed an increase in metazoan diversity and ecological complexity, marking the inception of the Cambrian Explosion. To constrain the drivers of this diversification, we combine redox and nutrient data for two shelf transects, with an inventory of biotic diversity and distribution from the Nama Group, Namibia (~550 to ~538 Million years ago; Ma). Unstable marine redox conditions characterised all water depths in inner to outer ramp settings from ~550 to 547 Ma, when the first skeletal metazoans appeared. However, a marked deepening of the redoxcline and a reduced frequency of anoxic incursions onto the inner to mid-ramp is recorded from ~547 Ma onwards, with full ventilation of the outer ramp by ~542 Ma. Phosphorus speciation data show that, whilst anoxic ferruginous conditions were initially conducive to the drawdown of bioavailable phosphorus, they also permitted a limited degree of phosphorus recycling back to the water column. A long-term decrease in nutrient delivery from continental weathering, coupled with a possible decrease in upwelling, led to the gradual ventilation of the Nama Group basins. This, in turn, further decreased anoxic recycling of bioavailable phosphorus to the water column, promoting the development of stable oxic conditions and the radiation of new mobile taxa.
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Affiliation(s)
- F T Bowyer
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK. .,University of Leeds, School of Earth and Environment, Leeds, LS2 9JT, UK.
| | - A J Shore
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK
| | - R A Wood
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK
| | - L J Alcott
- University of Leeds, School of Earth and Environment, Leeds, LS2 9JT, UK
| | - A L Thomas
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK
| | - I B Butler
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK
| | - A Curtis
- University of Edinburgh, School of GeoSciences, James Hutton Road, Edinburgh, EH9 3FE, UK
| | - S Hainanan
- Ministry of Mines and Energy, 6 Aviation Road, Private Bag, 13297, Windhoek, Namibia
| | | | - A M Penny
- Finnish Museum of Natural History, University of Helsinki, Jyrängöntie 2, 00560, Helsinki, Finland
| | - S W Poulton
- University of Leeds, School of Earth and Environment, Leeds, LS2 9JT, UK
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