Decline and fall of the Ediacarans: late‐Neoproterozoic extinctions and the rise of the modern biosphere

Biological reviews/Biological reviews of the Cambridge Philosophical Society, Journal Year: 2023, Volume and Issue: 99(1), P. 110 - 130

Published: Sept. 4, 2023

The end-Neoproterozoic transition marked a gradual but permanent shift between distinct configurations of Earth's biosphere. This interval witnessed the demise enigmatic Ediacaran Biota, ushering in structured trophic webs and disparate animal body plans Phanerozoic ecosystems. However, little consensus exists on reality, drivers, macroevolutionary implications extinctions. Here we evaluate potential drivers late-Neoproterozoic turnover by addressing recent findings geochronology, persistence classical macrobionts into Cambrian, existence crown-group eumetazoans. Despite renewed interest possibility Phanerozoic-style 'mass extinctions' latest Neoproterozoic, our synthesis available evidence does not support extinction models based episodic geochemical triggers, nor it validate simple ecological interpretations centred direct competitive displacement. Instead, argue that protracted indirect effects early bilaterian innovations, including escalations sediment engineering, predation, largely understudied impacts reef-building, may best account for temporal structure possible selectivity We integrate these processes generalised model eumetazoan-dominated ecologies, charting disruption spatial isotropy benthos as consequence diversifying macrofaunal interactions. Given nature resource distribution continuities among Cambrian faunas, convergent origins ecologically disruptive innovations bilaterians suggest rise Phanerozoic-type biotas have been unstoppable.

Language: Английский

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Priapulid neoichnology, ecosystem engineering, and the Ediacaran–Cambrian transition

Palaeontology, Journal Year: 2024, Volume and Issue: 67(4)

Published: July 1, 2024

Abstract The evolutionary rise of powerful new ecosystem engineering impacts is thought to have played an important role in driving waves biospheric change across the Ediacaran–Cambrian transition (ECT; c . 574–538 Ma). Among most heavily cited these bioturbation (organism‐driven sediment disturbance) as activities been shown critical downstream geobiological impacts. In this regard priapulid worms are crucial; trace fossils left by priapulan‐grade animals now recognized appearing shortly before base Cambrian and represent some earliest examples bed‐penetrative bioturbation. Understanding priapulids may thus be key reconstructing drivers ECT. However, rare modern benthic ecosystems, comparatively little known about behaviours associated with their burrowing. Here, we present early results neoichnological experiments focused on understanding worms. We observe for first time a variety burrowing (including formation linked burrow networks long in‐burrow residence times) hinting at larger group than previously thought. Finally, identify means which contribute our tracemakers ECT, they had shaping latest Ediacaran biosphere.

Language: Английский

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Life on the Edge: The Cambrian Marine Realm and Oxygenation

Annual Review of Earth and Planetary Sciences, Journal Year: 2023, Volume and Issue: 52(1), P. 109 - 132

Published: Dec. 8, 2023

The beginning of the Phanerozoic saw two biological events that set stage for all life was to come: (a) Cambrian Explosion (the appearance most marine invertebrate phyla) and (b) Great Ordovician Biodiversification Event (GOBE), subsequent substantial accumulation biodiversity. Here, we examine current state understanding environments ecosystems from late Ediacaran through Early Ordovician, which spans this biologically important interval. Through a compilation review existing geochemical, mineralogical, sedimentological, fossil records, argue interval one sustained low variable oxygen levels both led animal extinction fostered biodiversification throughout Ordovician. Therefore, existed on edge—with enough sustain them but with perennial risk environmental stressors could overwhelm them.▪We research geochemistry paleontology periods.▪Low oscillating in realm promoted diversification evolutionary innovation also drove several events.▪Taphonomic modes authigenic pathways were abundant supported by oceans persistently less oxygenated than today's oceans.

Language: Английский

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Oxygen increase and the pacing of early animal evolution

Global and Planetary Change, Journal Year: 2024, Volume and Issue: 233, P. 104364 - 104364

Published: Jan. 14, 2024

While it is widely accepted that early animals originated and primarily evolved during the Neoproterozoic to Cambrian period, there remains ongoing debate over how fluctuations in marine-atmospheric oxygen levels influenced their evolution diversification. To investigate this, we analyzed pristane/phytane ratios—a redox-proxy based on organic geochemistry—in surface sediments from Cryogenian successions South China, Oman, Australia. The temporal changes this proxy exhibited consistent patterns across all sites, revealing five cycles of anoxic oxic conditions ocean between 660 510 Ma. By examining average ratios, identified three events when increased. This represents a transition anoxic-dysoxic boundary at 630–600 Ma, followed by shift dysoxic 570 Ma (Shuram event), finally reaching 520 (Cambrian explosion). Significantly, these oxygenation align with eumetazoan evolution. An inverse relationship was observed oceanic redox positive/negative shifts δ13Ccarb, occurring first second events, suggesting an increase atmospheric levels. Based findings, propose were global increases levels, least Ediacaran period. These likely played role influencing rate among animals.

Language: Английский

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Trends in estuarine pyrite formation point to an alternative model for Paleozoic pyrite burial

Geochimica et Cosmochimica Acta, Journal Year: 2024, Volume and Issue: 374, P. 51 - 71

Published: April 16, 2024

The early Paleozoic Era (∼540–420 Ma) was an interval of profound biogeochemical changes including increasing oxygen (O2) and the onset bioturbation (sediment mixing by animals). It is hypothesized that incipient caused a monotonic decrease in sedimentary burial pyrite (FeS2), which would have slowed atmospheric O2 accumulation. However, accumulation can exhibit complex responses to dynamic, low-O2 environmental conditions. To assess potential modern analogue environments, we collected sediment cores from Chesapeake Bay, estuary with multiple gradients sulfate concentration, hypoxia intensity, organic carbon flux lability, bioturbation. Results indicate maximized not under strong depletion highly reducing sediments, but rather sediments occupy mid-range sulfate–chloride ratios. This probably occurs through efficient replenishment pore water and/or generation sulfur redox intermediates, promote formation via polysulfide reaction pathway. In light these results contrast earlier models, hypothesize mild temporarily increased efficiency stimulating higher reduction rates sulfide retention. Compiled data geochemical database median sulfur-carbon ratios fine-grained marine siliciclastic rocks Ediacaran Ordovician, then decreased became much less variable Silurian onward. Thus, Cambrian Ordovician Periods may constitute distinct Proterozoic-Phanerozoic transition accelerated buildup. ended Silurian, when pO2 rose sufficient levels homogenize carbon–sulfur cycling.

Language: Английский

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From organisms to biodiversity: the ecology of the Ediacaran/Cambrian transition

Paleobiology, Journal Year: 2025, Volume and Issue: unknown, P. 1 - 24

Published: Jan. 21, 2025

Abstract The Ediacaran/Cambrian transition (ECT; ~575–500 Ma) captures the early diversification of animals, including oldest crown-group taxa most major animal phyla alive today. Key to understanding drivers underneath ECT macroevolutionary patterns are interactions animals with one another and their environment, how these scale up global diversity patterns. Understanding ecology organisms is enabled by abundance Lagerstätten over this time period, a relatively large proportion soft-bodied preserved, often within communities in which they lived. Here, we review our organismal, community, macroecology ECT, different scales ecological analyses relate see 75 Myr period. Across all scales, find clear trends, starting stochastic ecosystem dynamics dominated generalist first Ediacaran communities, more structured, niche-driven specialist Cambrian Epoch 2. These trends reflected organism functional morphology, complexity strength organisms’ large-scale metacommunity, biogeographic, biodiversity Yet there delay between origination new type interaction when it observed impact as whole. As such, while many modern innovations were place end Cambrian, knock-on effects continued build throughout Phanerozoic, leading complex biosphere have

Language: Английский

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Early colonization of the deep-sea bottom—The protracted build-up of an ecosystem

Proceedings of the National Academy of Sciences, Journal Year: 2025, Volume and Issue: 122(8)

Published: Feb. 10, 2025

Our understanding of the patterns and processes behind evolution deep-marine ecosystems is limited because body-fossil record deep sea poor. However, that gap in knowledge may be filled as deposits are host to diverse abundant trace fossils activities benthic organisms. Here, we built a global dataset trace-fossil occurrences from comprehensive survey 720 Ediacaran–Devonian units show establishment modern-style ecosystem was protracted coincident with cooling increase oxygenation during Ordovician. The formation open burrows have increased bioirrigation uppermost sediment zone, promoting ventilation generating an engineering feedback loop between bioturbation pore-water oxygenation. Sharp changes Devonian originated oxygen variations resulting climate-controlled oceanic circulation.

Language: Английский

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Fossil Lagerstätten and the enigma of anactualistic fossil preservation

Paleobiology, Journal Year: 2025, Volume and Issue: unknown, P. 1 - 15

Published: March 11, 2025

Abstract Over the last 50 years, paleobiology has made great strides in illuminating organisms and ecosystems deep time through study of often-curious nature fossil record itself. Among deposits, none are as enigmatic or important to our understanding history life Konservat-Lagerstätten, deposits that preserve soft-bodied fossils thereby retain disproportionately large amounts paleobiological information. While Konservat-Lagerstätten often viewed curiosities record, decades have led a better environments circumstances exceptional fossilization.Whereas most types preservation require very specific sets conditions, which rare but can occur at any time, Seilacher noted problem “anactualistic” modes preservation, defined fossilization restricted no longer occur. Here, we focus on anactualistic widely recognized overrepresentation Ediacaran early Paleozoic. Ediacaran, Cambrian, Early Ordovician age encompass number fossilization, signal is driven by only two modes, Ediacara-type Burgess Shale–type preservation. Both “extinct” present marine environments. We consider controls promoted widespread Paleozoic their implications for environmental conditions complex first proliferated oceans.

Language: Английский

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Trace fossils from the Meishucun section of South China: revisiting ichnotaxonomy, behavioural diversification and ecosystem engineering from a key Ediacaran–Cambrian succession

Papers in Palaeontology, Journal Year: 2025, Volume and Issue: 11(2)

Published: March 1, 2025

Abstract The Ediacaran–Cambrian transition was a time of profound geobiological revolution and sedimentary change in Earth's history, including arguably the most dramatic evolutionary radiation remarkable biotic replacement. complex feedback between diversification metazoans their ecological interactions, especially after extinction latest Ediacaran biota, is still debated. Here, we systematically studied trace fossil content succession from Meishucun section South China. A total 20 ichnogenera comprising 31 ichnospecies have been identified succession. occurrence Treptichnus pedum Lower Phosphate Zhongyicun Member reinforces importance this ichnotaxon as an indicator boundary. Our critical review record key shows that increases ichnodiversity, ichnodisparity, degree bioturbation, bioturbation depth were accompanied by modes life ecosystem engineering throughout early Cambrian. stepped increased ichnodiversity ichnodisparity transition, simple morphologies to branching Fortunian, finally horizontal looping trails suspension feeding burrows Cambrian Stage 2, paralleled shift information agronomic revolution. hike intensity occurred during 2 may resulted increase bioirrigation levels conducive further deepening redox discontinuity surface.

Language: Английский

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The Balanoglossites ichnofabrics in the aftermath of the Permian-Triassic mass extinction

Sedimentary Geology, Journal Year: 2025, Volume and Issue: unknown, P. 106877 - 106877

Published: March 1, 2025

Language: Английский

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