Abstract

Silurian brachiopod faunas, which were relatively cosmopolitan, gave way to mildly provincial faunas in the Early Gedinnian. During Late Gedinnian (New Scotland) time provinciality first became marked so that distinct brachiopod assemblages characterize the Appalachian Province from Gaspe to northern Mexico. In Eurasia and southeastern Australia the Late Gedinnian was characterized by forms that define an Old World Province, which in contrast to the Appalachian Province, is characterized at the generic level by a larger number of typically Silurian holdovers. Endemic Gedinnian forms of southeastern Australia were sufficient to define a Tasman Subprovince of the Old World Province.

During Siegenian time provinciality increased with the addition of the Rhenish facies (Rhenish-Bohemian Subprovince) in parts of Gaspe, Nova Scotia, North Africa, and central Europe. The Bohemian facies was more widespread and included east-central Europe, Asia, and North Africa. In the Uralian region the emergence of Karpinskia as an endemic form signaled the beginning of Uralian provinciality for a brachiopod fauna otherwise closely related to the fauna of the Bohemian facies of the Rhenish-Bohemian Subprovince. Boundaries of the Appalachian and Old World Provinces remained relatively stable except for Nevada which experienced a great influx of typical Appalachian forms after the earliest Siegenian at the expense of the previously established Old World assemblage. A few genera migrated to Asia and southeastern Australia via a circum-north Pacific route.

During Early Emsian time marine deposition was more widespread, but provinciality increased by addition of the Malvinokaffric Province which includes southern South America, South Africa, and Antarctica. Southeastern Australia, New Zealand, and the Uralian region constitute separate subprovinces 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 maintained its identity until the Late Devonian.