Results 121 to 130 of about 282 (159)

Late Ordovician Mass Extinction: Earth, fire and ice. [PDF]

Natl Sci Rev
Harper DAT.
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Report on Canadian graptolites

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Graptolite reflectance anomaly

International Journal of Coal Geology, 2022
Thermal maturation is traditionally evaluated based on vitrinite reflectance (VRo) measurements and its relationship to oil and gas generation and diagenetic transformation are ingrained in many basin modeling tools. However, vitrinite derives from higher land plants that evolved in Devonian.
Zheng, Xiaowei, Schovsbo, Niels H., Luo, Qingyong, Wu, Jia, Zhong, Ningning, Goodarzi, Fariborz, Sanei, Hamed   +6 more
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Graptolite ontogeny and the size of the graptolite zooid

Geological Magazine, 1995
AbstractTwo methods of estimating the size of the graptolite zooid are described and discussed. It is possible to size a zooid by reference to cortical bandages or with reference to modem Rhabdopleura and its tubes. These two methods give very different results, with the first suggesting small zooids relative to thecal size and the second suggesting ...
Susan Rigby, Margaret Sudbury
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Molecular taphonomy of graptolites

Journal of the Geological Society, 2006
Graptolites are important fossils in Early Palaeozoic assemblages. Preserved graptolite periderm consists dominantly of an aliphatic polymer, immune to base hydrolysis. It contains no protein even though its structure, and chemical analyses of the periderm of the living relative Rhabdopleura
Gupta, NS, Briggs, DEG, Pancost, RD
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Early Devonian graptolites and graptolite biostratigraphy, Arctic Islands, Canada

Canadian Journal of Earth Sciences, 2013
The Early Devonian graptolite fauna of the Arctic Islands comprises the highest species content (17 species) in the world. In spite of this richness, no new species have been recognized; instead already-existing species, scattered around the then-known continents, suggest that relatively complete cosmopolitanism held sway for graptolites.
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Extinction of the graptolites

Geological Society, London, Special Publications, 1979
Summary Graptoloids became extinct in latest Early Devonian (Pragian) times, and dendroids in the late Carboniferous. There is insufficient information for the other six graptolite orders to suggest when they might have become extinct, so that in these cases it is impossible as yet to speculate how extinction occurred.
T. N. Koren’, R. B. Rickards
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Mode of secretion of graptolite periderm, in normal and retiolite graptolites

Geological Society, London, Special Publications, 1986
Summary The construction of graptolite periderm is discussed with particular reference to the rival extra-thecal tissue (secretion) and pterobranch (mortaring) models, and it is concluded that only the former model fits the observed structures.
D. E. B. Bates, N. H. Kirk
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Graptolites in British stratigraphy

Geological Magazine, 2009
Abstract697 taxa of planktonic graptolites are recorded, and their stratigraphical ranges are given, through 60 biozones and subzones in the Ordovician and Silurian strata of England, Wales and Scotland, in the first such stratigraphical compilation for Great Britain since the synthesis of Elles & Wood (1901–1918).
Zalasiewicz, J., Taylor, L., Rushton, A., Loydell, David, Rickards, R., Williams, Mark   +5 more
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XXXVI. On Graptolites

Transactions of the Geological Society of Glasgow, 1882
I n the first edition of his famous work, the “Systema Naturæ,” published in 1736, the great Swedish naturalist, Linnæus, proposed the name Graptolithus for certain natural markings occasionally found upon stones, which are not true fossils, but are mere superficial stainings, having the ...
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