Destabilization of the oceanic density structure and its significance to marine “extinction” events

Wilde, P.; Berry, William B. N.

doi:10.1016/0031-0182(84)90041-5

Cited by 135 publications

(50 citation statements)

References 26 publications

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“…In fact, most mass extinction events are believed to be caused by stresses on the ecosystem coming from external causes, such as drops in sea level, 14 impacts of extraterrestrial bodies, 15 climate change, 16 or changes in the level of oxygen in the oceans. 17 Both this issue, and the issue of the value of the exponent have been addressed by another simple model of extinction proposed by Newman (that's me).…”

Section: The Model Of Bak and Sneppenmentioning

confidence: 99%

A Model for Evolution and Extinction

Roberts

Newman

1996

Journal of Theoretical Biology

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This article gives a brief introduction to the mathematical modeling of large-scale biological evolution and extinction. We give three examples of simple models in this field: the coevolutionary avalanche model of Bak and Sneppen, the environmental stress model of Newman, and the increasing fitness model of Sibani, Schmidt, and Alstrøm. We describe the features of real evolution which these models are intended to explain and compare the results of simulations against data drawn from the fossil record.

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Section: The Model Of Bak and Sneppenmentioning

confidence: 99%

A Model for Evolution and Extinction

Roberts

Newman

1996

Journal of Theoretical Biology

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“…Cloud 1983;Holland 1984;Wilde & Berry 1984) have generally identified a rise in atmospheric oxygen through the Palaeozoic, with initial low oxygen levels being linked to the abundance of early Palaeozoic anoxic mudstones. The characteristic 'anoxic black shale' facies within which graptolites are frequently abundant are not, however, restricted to the Lower Palaeozoic, but are found periodically from Cambrian to Carboniferous, and again within the Mesozoic (Leggett et al, 1981;Wilde & Berry 1984). Even within these 'anoxia rich' periods, the existence of oxygen poor basinal conditions was not continuous, with several aerated phases being recorded, such as within the Ashgill (Berry 1989;Leggett et al, 1981), upper Llandovery and uppermost Wenlock (Kemp 1991).…”

Section: Graptolitic Ecogroupsmentioning

confidence: 99%

“…Even within these 'anoxia rich' periods, the existence of oxygen poor basinal conditions was not continuous, with several aerated phases being recorded, such as within the Ashgill (Berry 1989;Leggett et al, 1981), upper Llandovery and uppermost Wenlock (Kemp 1991). There thus appears to be little fundamental difference between lower Palaeozoic and Post-Silurian oceanic conditions, with atmospheric oxygen levels not integrally linked to that within oceanic systems, which appear to be far more dependant on transgressive/regressive cycles and the presence of glacial episodes (Wilde & Berry 1984).…”

Section: Graptolitic Ecogroupsmentioning

confidence: 99%

The position of graptolites within Lower Palaeozoic planktic ecosystems

Underwood

1993

LET

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An integrated approach has been used to assess the palaeoecology of graptolites both as a discrete group and also as a part of the biota present within Ordovician and Silurian planktic realms. Study of the functional morphology of graptolites and comparisons with recent ecological analogues demonstrates that graptolites most probably filled a variety of niches as primary consumers, with modes of life related to the colony morphotype. Graptolite coloniality was extremely ordered, lacking any close morphological analogues in Recent faunas. To obtain maximum functional efficiency, graptolites would have needed varying degrees of coordinated automobility. A change in lifestyle related to ontogenetic changes was prevalent within many graptolite groups. Differing lifestyle was reflected by differing reproductive strategies, with synrhabdosomes most likely being a method for rapid asexual reproduction. Direct evidence in the form of graptolithophage 'coprolitic' bodies, as well as indirect evidence in the form of probable defensive adaptations, indicate that graptolites comprised a food item for a variety of predators. Graptolites were also hosts to a variety of parasitic organisms and provided an important nutrient source for scavenging organisms.

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“…Although the biotic crisis and related marine events have been attributed to a range of factors, e.g. bolide impacts, tectonism and climate change, oceanic overturn, and eustatic £uctuations (McLaren 1982;Wilde & Berry 1984;Johnson et al 1985;Copper 1986;Geldsetzer et al 1987;Ettensohn et al 1988a;Wang 1992), few if any of these proposals have attempted to link Devonian marine phenomena to coeval developments in the terrestrial realm. Algeo et al (1995) presented the hypothesis that the Middle-to-Late Devonian biotic crisis, and related events in the marine realm, were precipitated by the evolutionary development of vascular land plants.…”

Section: Introductionmentioning

confidence: 99%

Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events

Algeo

Scheckler

1998

Phil. Trans. R. Soc. Lond. B

613

347

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The Devonian Period was characterized by major changes in both the terrestrial biosphere, e.g. the evolution of trees and seed plants and the appearance of multi-storied forests, and in the marine biosphere, e.g. an extended biotic crisis that decimated tropical marine benthos, especially the stromatoporoid-tabulate coral reef community. Teleconnections between these terrestrial and marine events are poorly understood, but a key may lie in the role of soils as a geochemical interface between the lithosphere and atmosphere/ hydrosphere, and the role of land plants in mediating weathering processes at this interface. The e¡ective-ness of terrestrial £oras in weathering was signi¢cantly enhanced as a consequence of increases in the size and geographic extent of vascular land plants during the Devonian. In this regard, the most important palaeobotanical innovations were (1) arborescence (tree stature), which increased maximum depths of root penetration and rhizoturbation, and (2) the seed habit, which freed land plants from reproductive dependence on moist lowland habitats and allowed colonization of drier upland and primary successional areas. These developments resulted in a transient intensi¢cation of pedogenesis (soil formation) and to large increases in the thickness and areal extent of soils. Enhanced chemical weathering may have led to increased riverine nutrient £uxes that promoted development of eutrophic conditions in epicontinental seaways, resulting in algal blooms, widespread bottomwater anoxia, and high sedimentary organic carbon £uxes. Long-term e¡ects included drawdown of atmospheric pCO 2 and global cooling, leading to a brief Late Devonian glaciation, which set the stage for icehouse conditions during the Permo-Carboniferous. This model provides a framework for understanding links between early land plant evolution and coeval marine anoxic and biotic events, but further testing of Devonian terrestrial^marine teleconnections is needed.

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Destabilization of the oceanic density structure and its significance to marine “extinction” events

Cited by 135 publications

References 26 publications

A Model for Evolution and Extinction

A Model for Evolution and Extinction

The position of graptolites within Lower Palaeozoic planktic ecosystems

Terrestrial-marine teleconnections in the Devonian: links between the evolution of land plants, weathering processes, and marine anoxic events

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