The Downton Series as the fourth Series of the Silurian System

Bassett, Michael G.; Lawson, J. D.; White, Dennis E.

doi:10.1111/j.1502-3931.1982.tb01114.x

Cited by 27 publications

(28 citation statements)

References 55 publications

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“…Thelodonts have been successfully used in biostratigraphy since the 1960's (Gross 1967) with current global zonation schemes (in Gradstein et al 2012) developed for the Silurian (Turner 1973;Bassett et al 1982;Märss et al 1995;Blom 1999;Talimaa 2000) and Devonian, (Turner 1995a(Turner , 1999Blom and Goujet 2002;Hairapetian et al, in press). Subsequent to the Givetian-Frasnian boundary, thelodonts are restricted to the margins of northern Gondwana (Turner 1997;Trinajstic 2001;Märss et al 2007) and there is a marked reduction in diversity with the Turinidae Family represented by the species Australolepis seddoni (Seddon 1969;Turner and Dring 1981;Trinajstic and George 2009), Turinia hutkensis (Blieck and Goujet 1978;Hairapetian et al 2006) and a new genus and species of turiniid (Hairapetian et al, in press).…”

Section: Biostratigraphymentioning

confidence: 99%

Upper Devonian microvertebrates from the Canning Basin, Western Australia

Roelofs

Playton

Barham

et al. 2015

Acta Geologica Polonica

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A diverse microvertebrate fauna is described from the Virgin Hills and Napier formations, Bugle Gap Limestone Canning Basin, Western Australia. Measured sections at Horse Spring and Casey Falls (Virgin Hills Formation) and South Oscar Range (Napier Formation) comprise proximal to distal slope carbonates ranging in age from the Late Devonian Frasnian to middle Famennian. A total of 18 chondrichthyan taxa are identified based on teeth, including the first record of Thrinacodus tranquillus, Cladoides wildungensis, Protacrodus serra and Lissodus lusavorichi from the Canning Basin. A new species, Diademodus dominicus sp. nov. is also described and provides the first record of this genus outside of Laurussia. In addition, the upper range of Australolepis seddoni has been extended to Late Devonian conodont Zone 11, making it the youngest known occurrence for this species. The Virgin Hills and Napier formations microvertebrate faunas show close affinities to faunas recovered from other areas of Gondwana, including eastern Australia, Iran, Morocco and South China, which is consistent with known conodont and trilobite faunas of the same age.

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Section: Biostratigraphymentioning

confidence: 99%

Upper Devonian microvertebrates from the Canning Basin, Western Australia

Roelofs

Playton

Barham

et al. 2015

Acta Geologica Polonica

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“…those from the wellknown Upper Silurian Downton Group, Pridoli Series succession at Ludlow, Shropshire, England (Bassett et al 1982) and, like ironstones, their formation has often been linked to the development of a condensed section (e.g. Kidwell 1989).…”

Section: 'Bone-beds'mentioning

confidence: 99%

Sedimentological and geochemical controls on ooidal ironstone and ‘bone-bed’ formation and some comments on their sequence-stratigraphical significance

Macquaker

Taylor

Young

et al. 1996

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Ironstones and 'bone-beds' are both formed in shallow marine settings where the prevailing sediment accumulation rates are very low. A review of published work shows that both sediment types cap coarsening upward successions and are commonly developed in mudstonedominated settings. Both can be shown to contain similar sedimentary structures (e.g. rip-up clasts, disarticulated shell debris) and a diverse assemblage of ichnogenera, However, the early diagenetic assemblages within each sediment type are both different from each other and from the mudstones within which they are enclosed. In ooidal ironstones, the cement assemblage comprises glaucony, berthierine and siderite; in 'bone-beds' it comprises early apatite, glaucony and later calcite and pyrite; in the mudstones it is predominantly pyrite. It is argued that the physical environment in which the ironstones and 'bone-beds' formed was similar, whereas their diagenetic environments were rather different. In particular, the characteristic cement assemblage of ironstones was produced in suboxic pore waters which were subjected to intense Fe reduction, whereas the characteristic cement assemblage of 'bone-beds' was produced in suboxic pore waters where there was limited Fe reduction. As a consequence of these chemical and stratigraphical constraints it is believed that 'bone-beds' formed on marine flooding surfaces and ironstones formed either at sequence boundaries, major flooding surfaces or maximum flooding surfaces.

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“…It plays a central role in atmospheric chemistry (4), but its role in aquatic environments is less clearly understood (3,5). Flash photolysis studies (2) demonstrated that -OH is formed in seawater, and a few model calculations of-OH production rates and concentrations in surface seawater have been reported (6,7).…”

mentioning

confidence: 99%

“…1, E and R), this being the first demonstration of stomata in the Silurian. The lower part of the LBBM, and underlying Upper Whitcliffe Formation, contain fully marine faunas (5); the bone beds represent lag deposits of drifted debris formed in a very shallow subtidal to low intertidal environment, possibly deposited in storms (6). The restricted fauna of the upper part of the LBBM and PSM, suggests that the biota was deposited in an environment of reduced salinity.…”

mentioning

confidence: 99%

Land Animals in the Silurian: Arachnids and Myriapods from Shropshire, England

Jeram¹,

Selden²,

Edwards³

1990

Science

189

117

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A new assemblage of arthropod cuticles from Upper Silurian rocks in Shropshire, England, includes at least two centipedes and a trigonotarbid arachnid. This unequivocal terrestrial fauna from the Silurian constitutes the earliest direct record of land animals. The presence of predatory arthropods suggests that complex terrestrial ecosystems were in place by the late Silurian (414 x 10(6) years before present) and that the animal invasion of the land occurred earlier than was previously thought.

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The Downton Series as the fourth Series of the Silurian System

Cited by 27 publications

References 55 publications

Upper Devonian microvertebrates from the Canning Basin, Western Australia

Upper Devonian microvertebrates from the Canning Basin, Western Australia

Sedimentological and geochemical controls on ooidal ironstone and ‘bone-bed’ formation and some comments on their sequence-stratigraphical significance

Land Animals in the Silurian: Arachnids and Myriapods from Shropshire, England

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