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Showing 1 to 6 of 6 (0.044 seconds)Spelling suggestions: "subject:"famennian"" "subject:"famenniano""
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The Arthropod Assemblage of the Upper Devonian Strud locality and its EcologyLagebro, Linda January 2015 (has links)
The Devonian (419-359 million years ago) is the geological period when the terrestrial biota fully established. Early representatives from a terrestrial and continental aquatic biota have previously been reported from the Upper Devonian (Famennian) Strud quarry in Belgium, in the shape of seed-bearing plants and vertebrates (fish and early tetrapods). The palaeoenvironment is interpreted as a floodplain with slow accumulation of sediment in the river channels and adjacent shallow pools, subject to seasonal flooding and desiccation. This thesis presents the upper Famennian Strud ecosystem with representatives from the largest animal phylum – the Arthropoda. Pancrustaceans are dominating the arthropod assemblage by two eumalacostracans (previously described), three groups of branchiopods, and a putative insect, all collected in fine shales likely deposited in the shallow pools. The branchiopods from Strud comprise new members from all three extant clades, i.e. notostracans, anostracans, and spinicaudatan diplostracans. The notostracan Strudops goldenbergi is remarkable for its close resemblance with the extant genus Triops by the overall body plan and telson morphology. A phylogenetic analysis including modern and extinct notostracans and anostracans was performed, where Strudops appears as the earliest undisputed notostracan ever found. In addition, new genera of Anostraca (Haltinnaias serrata) and Spinicaudata (Gesvestheria pernegrei) are described herein. The insect Strudiella devonica consists of a single specimen and is interpreted to have been a nymph due to its minute size and wingless appearance. The chelicerates are represented by one or several species of eurypterids. So far unnamed juvenile eurypterid remains have also been found within the pool strata, and fragments of adult individuals in the coarser river deposits. The branchiopod community displays a unique insight to the ecosystem that these crustaceans inhabited. This is partly because of their co-occurrence, but mainly because they are preserved in close association to draught-resistant encysted eggs, in the same manner as modern day branchiopods do to survive and disperse during periods of drought and freezing. Altogether, the arthropod assemblage offers insight to Late Devonian freshwater ecosystems, and provides further understanding of the evolution of respective groups.
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Revision of the Upper Devonian in the Central-Southern Appalachian Basin: Biostratigraphy and LithostratigraphyBrame, Roderic Ian 27 January 2003 (has links)
The Upper Devonian of the central-southern Appalachians Valley and Ridge province of Virginia lacks stratigraphic resolution, revised formal nomenclature, and detailed biostratigraphic data. Eight of the most complete sections available in a three thousand square mile area were used to build a framework for revising the stratigraphy of the Upper Devonian strata in southwestern Virginia. Detailed lithologic descriptions of about four thousand feet (1.3 km) of rock were made at each outcrop. John Dennison's (1970 and 1976) nomenclature for the Upper Devonian along the Alleghany Front was successfully tested for it usefulness in Southwestern Virginia and are hereby applied to these rocks. The stratigraphic interval ranges in age from the Middle Devonian to the Lower Carboniferous. The stratigraphic units include the Middle Devonian Millboro Shale, the Upper Devonian Brallier, Scherr, Foreknobs (formally the "Chemung"), Hampshire, and the Lower Carboniferous Price Formation. The Brallier contains two members (Back Creek Siltstone and Minnehaha Springs), the Foreknobs is divided into five members (Mallow, Briery Gap, Blizzard, Pound, and Red Lick), and the lower Price is divided into three members (the Cloyd Conglomerate, Sunbury Shale, and the Ceres). 23046 fossils were collected and 160 taxa were identified. The biostratigraphic range of each taxon was compiled, analyzed, and then divided into biostratigraphic zones. 19 local biozones are described. The Frasnian/Famennian boundary is accurately placed based on occurrences of internationally known index fossils. The Frasnian/Famennian extinction event is recognized and is determined to have two pulses. The local biostratigraphic zonations doubled the resolution of previous studies. Lithostratigraphic and biostratigraphic data were combined to look at the timing and rates of events. The lithostratigrapic divisions were tested to see if their boundaries are or are not time transgressive. The Brallier/Foreknobs, Blizzard/Pound, and Pound/Redlick boundaries are crossed by biozones. Conversely the Frasnian/Famennian boundary crosses the lithologic boundary between the Pound and Red Lick Members. This documents the prograding nature of the clastic wedge. Composite biostratigraphic ranges correlate with ranges in New York and western Maryland. This detailed lithostraigraphic and biostratigraphic study documents a comprehensive and higher resolution understanding of the Upper Devonian in the Central-Southern Appalachian Basin. / Ph. D.
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Reef recovery following the Late Devonian mass extinction: evidence from the Dugway Range, west-central UtahKrivanek, Joseph G 01 June 2006 (has links)
The biotic crisis of the Late Devonian Period involved three distinct peaks of extinction intensity and preferentially eliminated reef taxa. By the end of the second peak, the Frasnian-Famennian (F-F) boundary, the dominant constructor guild member of the mid-Paleozoic, the stromatoporoids, had ceased reef construction in most parts of the world. An undescribed stromatoporoid bioherm in the Dugway Range, west-central Utah, is one of the few locations where stromatoporoids continued building reefs into the mid-Famennian. The sections are well-constrained biostratigraphically using both conodonts and stromatoporoids and range from the latest Frasnian to the Early Carboniferous. The reefal faunas are depauperate and dominated by labechiids and stylostromids, as is characteristic of most Famennian bioconstructions. In this region, reefal development was episodic with reefal units interbedded with units lacking reef taxa. The stromatoporoid survivors belong to long-ranging clades, and may represent "extinction-resistant" taxa. Both were fairly minor constituents of Frasnian reef communities.
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Sequence Stratigraphic Framework for the Upper Devonian Lower-Huron Shale Member of the Ohio Shale, North-Central Appalachian BasinCullen, Patrick James 11 June 2018 (has links)
No description available.
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Paleontology Of Middle And Upper Devonian Formations Of Northwest Ohio: Documenting Earth System Evolution For Scientific And Educational PurposesMason, Chad R. 14 August 2019 (has links)
No description available.
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Geochemie Porifera-reicher Mud Mounds und Mikrobialithe des Mittel- und Oberdevons (Westaustralien, Nordfrankreich) / Geochemistry of Porifera-rich mud mounds and microbialites of the Middle and Upper Devonian (Western Australia, Northern France)Hühne, Cathrin 07 November 2005 (has links)
No description available.
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