Ecological reinterpretation of the dysaerobic Leiorhynchus fauna: Upper Devonian Geneseo Black Shale, Central New York ( USA) .

J. B. Thompson, C. R. Newton

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Abstract

The anomalous Leiorhynchus brachiopod fauna of the Upper Devonian Geneseo Shale is here reinterpreted as a gregarious and opportunistic epifaunal suspension-feeding assemblage that inhabited dysaerobic environments within the Appalachian Basin. This reinterpretation is based on detailed paleoecology, petrography, x-radiography, SEM, and organic analyses of the upper portion of the Geneseo Shale. Available evidence indicates a reclining mode of life for Leiorhynchus quadracostatus, with the brachial valve oriented up. Abundant Leiorhynchus occur in aggregates or clumps with a mean density of 14/m 2. The zone of abundant Leiorhynchus also correlates with the highest measured weight percent of organics (6.0%) within the section. The Leiorhynchus are also strongly aligned to a weak current within the basin; mean direction of Leiorhynchus beaks is 42o, mean hinge direction is 122o. The presence of a weak current is also supported by small-scale cross-laminations and small starved ripples in silty layers. - from Authors brachiopod Appalachian Basin paleoecology petrography x radiography Dept of Geology, Syracuse Univ, Syracuse, NY 13244, USA.

Original languageEnglish (US)
Pages (from-to)274-281
Number of pages8
JournalPalaios
Volume2
Issue number3
DOIs
StatePublished - 1987

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ASJC Scopus subject areas

  • Palaeontology
  • Ecology, Evolution, Behavior and Systematics

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