Results 181 to 190 of about 4,290 (216)

Frasnian-Famennian extinctions

1982
Extinctions are continuous throughout the Phanerozoic. Although a single natural phenomenon brought about by environmental change at any scale, they may be conveniently divided into two classes: background extinction and mass extinction (Raup and Sepkoski, 1982).
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Frasnian–Famennian biotic crisis: undervalued tectonic control?

Palaeogeography, Palaeoclimatology, Palaeoecology, 1998
The prime cause of the Late Devonian Kellwasser crisis, culminating in a mass extinction event near the Frasnian–Famennian (F–F) boundary, remains conjectural. Nevertheless, rapid sea-level fluctuations of uncertain origin during tectono-eustatic highstand, paired with repeated oceanic anoxia and climatic changes, are usually thought at present to be ...
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On Frasnian ammonoids of the New Siberian Islands

Paleontological Journal, 2009
Ammonoids from the basal beds of the Nerpalakh Formation (Lower Frasnian) of Belkovsky Island (New Siberian Archipelago) are systematically studied. Taxonomically, the assemblage studied (Manticoceras insulare sp. nov., Tornoceras typum (Sandberger, 1851), and T.
S. V. Nikolaeva, A. B. Kuzmichev, V. A. Aristov   +2 more
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Atrypid Brachiopods from the Upper Devonian Wangchengpo Formation (Frasnian) of Southern Guizhou, China-Extinction Patterns in the Frasnian of South China

Acta Geologica Sinica - English Edition, 2005
The Wangchengpo Frasnian section of Dushan County contains two atrypid brachiopod assemblages. The lower is characterized by the Atryparia (Costatrypa) dushanensis fauna that appears at the base of the Hejiazhai Member approximately in the falsiovalis to transitans conodont zones; the upper is characterized by the Radiatrypa yangi fauna, which appears ...
MA Xueping, Paul COPPER, SUN Yuanlin, LIAO Weihua   +3 more
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Quantification of outlines in Frasnian (Upper Devonian) platform conodonts

Canadian Journal of Earth Sciences, 1986
The outline of the platform in Pa elements of conodont genera such as Palmatolepis is commonly one of the most heavily weighted taxonomic characters. But a taxonomy based only on visual discrimination of Pa elements of Frasnian species of Palmatolepis has resulted in widespread misidentification.
Gilbert Klapper, C. T. Foster Jr.
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The late Frasnian (Upper Devonian) Kellwasser Crisis

2005
Detailed investigations of sequences containing the Kellwasser Bio-event near the Frasnian-Famennian boundary demonstrate a stepwise character of influences on different groups of organisms over a time span of more than 1 my. Therefore the term Kellwasser Crisis (KW Crisis) is introduced. Extraordinary episodes of the KW Crisis, like e.g.
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Preliminary analysis of frasnian, late devonian conodont biogeography

Historical Biology, 1995
Although conodont endemism was not as high in the Frasnian as in earlier Devonian intervals, analysis of a limited number of intensively collected sections in the Montagne Noire, the United States and Canada, Western Australia, and the Russian Platform demonstrates levels of endemism ranging from about 30 to 35% in three composites of two zones each ...
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Maleimides across the Frasnian/Famennian boundary

Analysis of bound maleimides across the Late Devonian Frasnian/Famennian boundary from a core in the Illinois Basin, North America.
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The semichatovae Transgression (basal upper Frasnian) in Morocco

The semichatovae Transgression marks an episode of major eustatic sea level rise in the Upper Devonian. It is commonly described by the wide spread of the index conodont Palmatolepis semichatovae and has been proposed to define the boundary between the middle and upper Frasnian substages within Frasnian conodont zone 11. The index species is known from
Großklaus, Maximilian*, Becker, Ralph Thomas   +1 more
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Frasnian, adj.

2023
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