Palaeontological evidence bearing on global Ordovician–Silurian continental reconstructions

Fortey, Richard A.; Cocks, L. Robin M.

doi:10.1016/s0012-8252(02)00115-0

Cited by 314 publications

(208 citation statements)

References 132 publications

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“…The late Ordovician mass extinction has been related to a period of rapid cooling followed by a period of rapid global warming (Orth et al 1986;Brenchley et al 1994Brenchley et al , 1995Brenchley et al , 2003. Brenchley (1984), Brenchley et al (1991Brenchley et al ( , 1994Brenchley et al ( , 1995Brenchley et al ( , 2003, Briggs et al (1988), Owen et al (1991), Fortey & Cocks (2003), Sheehan (2001) and others have convincingly demonstrated how global cooling and warming events could have led to a mass extinction, and we do not dispute the contribution of global cooling to this extinction.…”

Section: Aspects Of the Late Ordovician Mass Extinction Potentially Cmentioning

confidence: 50%

Did a gamma-ray burst initiate the late Ordovician mass extinction?

Melott¹,

Lieberman

Laird³

et al. 2004

International Journal of Astrobiology

161

164

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Gamma-ray bursts (GRBs) produce a flux of radiation detectable across the observable Universe. A GRB within our own galaxy could do considerable damage to the Earth's biosphere; rate estimates suggest that a dangerously near GRB should occur on average two or more times per billion years. At least five times in the history of life, the Earth has experienced mass extinctions that eliminated a large percentage of the biota. Many possible causes have been documented, and GRBs may also have contributed. The late Ordovician mass extinction approximately 440 million years ago may be at least partly the result of a GRB. A special feature of GRBs in terms of terrestrial effects is a nearly impulsive energy input of the order of 10 s. Due to expected severe depletion of the ozone layer, intense solar ultraviolet radiation would result from a nearby GRB, and some of the patterns of extinction and survivorship at this time may be attributable to elevated levels of UV radiation reaching the Earth. In addition, a GRB could trigger the global cooling which occurs at the end of the Ordovician period that follows an interval of relatively warm climate. Intense rapid cooling and glaciation at that time, previously identified as the probable cause of this mass extinction, may have resulted from a GRB.

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Section: Aspects Of the Late Ordovician Mass Extinction Potentially Cmentioning

confidence: 50%

Did a gamma-ray burst initiate the late Ordovician mass extinction?

Melott¹,

Lieberman

Laird³

et al. 2004

International Journal of Astrobiology

161

164

View full text Add to dashboard Cite

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“…This fauna therefore represents a high latitude fauna, nearly comparable with that of the Fezouata Biota, although the latter was nearer to the South Pole (Fortey and Cocks 2003;Cocks and Torsvik 2004).…”

Section: Geological Settingmentioning

confidence: 82%

“…During the latest Tremadocian and earliest Floian, Avalonia was at high latitude, between 30° and 60° south, with the portion that became Wales being at about 60° south (Fortey and Cocks 2003;Cocks and Torsvik 2004), having broken off from Gondwana around the end of the Cambrian (Fortey and Cocks 2003). This fauna therefore represents a high latitude fauna, nearly comparable with that of the Fezouata Biota, although the latter was nearer to the South Pole (Fortey and Cocks 2003;Cocks and Torsvik 2004).…”

Section: Geological Settingmentioning

confidence: 97%

Middle Cambrian sponges from the Drum Mountains and House Range in western Utah

Rigby

Church²,

Anderson

2010

J. Paleontol.

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A diverse assemblage of Middle Cambrian sponges, recently collected from the Wheeler and Marjum Formations of western Millard County, Utah, includes a variety of demosponges and hexactinellids. This collection includes the verongiid Vauxia bellula Walcott, 1920, and the protomonaxonids Choia carteri and Choia ridleyi Walcott, 1920, Hamptonia bowerbanki Walcott, 1920, and Hamptonia parva n. sp. Hexactinellids in the collection include the reticulosid protospongioids Diagoniella hindei Walcott, 1920, and Diagoniella magna n. sp.; the dierespongioid hydnodictyid Valospongia? gigantus Rigby, 1973; and the hintzespongioid Hintzespongia bilamina Rigby and Gutschick, 1976. A specimen of the problematic Sentinelia? draco Walcott, 1920, is also documented as part of the collection.

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“…First, using the a priori knowledge of the palaeogeographical positions of each palaeocontinent in the Late Ordovician (Fortey & Cocks 2003, Jiménez-Sánchez & Villas 2010, the total sample was divided into two subsamples: a cold-water subsample (Mediterranean province) and a warm-water subsample (Avalonia region and Baltic and Laurentia-Siberian provinces). It is important to remember here that all of the genera selected for this study contain both cold-and warm-water species.…”

Section: Methodsmentioning

confidence: 99%

Palaeogeographical patterns in Late Ordovician bryozoan morphology as proxies for temperature

Jiménez-Sánchez¹,

Taylor²,

Gomez³

2013

Bull. Geosci.

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Several studies have revealed temperature-related patterns in recent bryozoans, both in the chemical composition of the skeleton and in the morphological characters of the colonies, but comparable studies on Palaeozoic bryozoans are lacking. In this paper a statistical analysis of the morphological differences is undertaken between congeneric species of some Ordovician bryozoans from warm-and cold-water settings. For this study ten eurythermic cosmopolitan bryozoan genera from the Upper Ordovician were selected from the Mediterranean, Avalonia, Baltic and Laurentia-Siberian provinces. These genera are: Ceramopora and Ceramoporella (Cystoporata); Diplotrypa, Eridotrypa, Hallopora, Heterotrypa, Monticulipora and Trematopora (Trepostomata); Graptodictya (Cryptostomata); and Kukersella (Cyclostomata). The study involved 154 samples belonging to 104 different species. Twenty-eight morphological characters were measured, although only 21 were used in the final statistical analysis. Univariate (t, F, Kolmogorov-Smirnov and Mann-Whitney tests), multivariate discriminant and multivariate ordination (Principal Coordinates, Principal Components, Correspondence, and Detrended Correspondence) analyses were performed on the data. For the univariate and multivariate discriminant analyses, the total set of samples was divided a priori into cold-and warm-water subsets based on palaeolatitude: samples from the Mediterranean province were attributed to the cold-water subset, whereas samples from Avalonia, Baltic and the Laurentian-Siberian provinces were included in the warm-water subset. For the multivariate ordination analysis no a priori grouping by water temperature was imposed, and the aim of these analyses was to test whether different samples were correctly arranged along a water temperature gradient. The univariate statistical analysis showed that there are clear morphological differences between cold-and warm-water species in six of the ten Late Ordovician bryozoan genera analysed in this study, although these differences are only evident for some of the characters used, and only when the analysis is performed on individual genera. The best characters to differentiate species by water temperature are those related to the size of the zooidal polymorphs, especially the diameters of the autozooecia, mesozooecia and exilazooecia. With the exception of one genus (Trematopora), cold-water species have larger zooids. The discriminant analysis was able to classify correctly as warm-or cold-water 100% of the samples for two genera, slightly below 95% for two other genera, and between 67% and 90% for the remaining six genera. Finally, the multivariate ordination analysis was able to separate species by palaeogeographical province in some genera, but these provinces were not correctly arranged along a palaeolatitudinal gradient using any of the methods used. • Key words: bryozoans, cosmopolitan genera, latitudinal adaptations, univariate and multivariate statistical analysis.

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Palaeontological evidence bearing on global Ordovician–Silurian continental reconstructions

Cited by 314 publications

References 132 publications

Did a gamma-ray burst initiate the late Ordovician mass extinction?

Did a gamma-ray burst initiate the late Ordovician mass extinction?

Middle Cambrian sponges from the Drum Mountains and House Range in western Utah

Palaeogeographical patterns in Late Ordovician bryozoan morphology as proxies for temperature

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