Early devonian brachiopod zoogeography

Arthur J. Boucot, J. G. Johnson, John A. Talent

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61 Citations (Scopus)

Abstract

Generically cosmopolitan Silurian brachiopod faunas were widely established in the Llandovery and Wenlock and to a lesser extent in the Ludlow and Pridoli. Ensuing Gedinnian provinciality resulted in the formation of two discrete faunal provinces, the Appalachian Province and the Old World Province, comprising, respectively, eastern North America from Gaspe to northern Mexico, and Eurasia, North Africa, southeastern Australia and western North America. Within the Old World Province, Gedinnian brachiopod genera were sufficiently restricted geographically to allow the definition of Rhenish-Bohemian and Tasman subprovinces. During Siegenian time, provinciality increased with the addition of parts of Nova Scotia to the Rhenish-Bohemian Subprovince and by the delineation of a Uralian Subprovince in much of the USSR Western North America remained a part of the Old World Province in the Siegenian, except for Nevada, which became an Appalachian Province enclave in the later Siegenian. During the Early Emsian, marine deposition was more widespread, but provincialism increased by the addition of the Malvinokaffric Province, which included southern South America, southernmost Africa, and Antarctica. New Zealand emerged as a separate subprovince of the Old World Province. Appalachian Province influence in Nevada ceased as endemic new forms appeared and were joined by genera again characteristic of the Old World Province, the mixture characterizing a Cordilleran Subprovince. Late Emsian, Eifelian, and Givetian brachiopods were more cosmopolitan, but the Appalachian Province and the Old World Province maintained their separate identity until approximately the Late Devonian. The Hamilton (Givetian) fauna of North America is notable for its content of some Old World Early Devonian forms which presumably migrated through Nova Scotia. The Rhenish-Bohemian Subprovince of the Old World Province includes shallow water (Rhenish) and deeper water (Bohemian or "Hercynian") animal communities, which are coincidentally associated with distinctive rock facies in Europe, but which elsewhere are not restricted to terrigenous or carbonate lithofacies. A cosmopolitan hoxadXonotid-Plectonotus association characterizes a widespread shallow water community occurring in all Provinces. Lower Devonian faunas of the Urals and Kazakhstan showed some important differences, probably due to community control. Kazakhstan faunas belonged to a Rhenish-like community while the Uralian faunas were patently of the Bohemian type. Disjunct Appalachian elements are present in Kazakhstan, and in southeastern Australia, and are believed to have migrated to those regions along a circum-north Pacific route. Some Tasman elements reached Kazahkstan and Manchuria. Mixtures of elements characteristic of particular provinces occur in boundary regions where different provinces adjoin, including Gaspe, Nevada, Bolivia, and New Zealand.

Original languageEnglish
Pages (from-to)1-59
Number of pages59
JournalSpecial Paper of the Geological Society of America
Volume119
DOIs
Publication statusPublished - 1969

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