Early Carboniferous spiriferoid brachiopods from the Qaidam Basin, Northwest China: taxonomy, biostratigraphy and biogeography

Six Early Carboniferous brachiopod species in four genera of the Superfamily Spiriferoidea are described from the Qaidam Basin, northwestern China, including a new genus, <i>Qaidamospirifer</i>, and two new species: <i>Grandispirifer qaidamensis</i> and <i>Qaidamospirifer elongatus</i>. Additionally, a new genus, <i>Triangulospirifer</i>, is also proposed to replace <i>Triangularia</i> (Poletaev, 2001) that was preoccupied by a Devonian molluscan genus. <br /><br />On the basis of the new material as well as published information, we have reviewed the taxonomic composition and the stratigraphic and palaeobiogeographic distributions of the three previously established genera from the viewpoint of palaeobiogeography. The study reveals that <i>Grandispirifer</i> has a relatively long stratigraphic range from the late Tournaisian to Serpukhovian. During this interval, the genus attained a wide geographical distribution, reaching Northwest China, western Yunnan of West China, Japan, as well as Iran and North Africa. <i>Angiospirifer</i> first occurred in western Europe in the Viséan, and later migrated to North Africa during the late Viséan. In the Serpukhovian, it migrated eastward, reaching the Donets Basin of Ukraine and the Qaidam Basin in Northwest China. <i>Anthracothyrina</i> evolved from <i>Brachythyrina</i> in North Africa in late Viséan, then dispersed north-westward to western and eastern Europe and, further eastward to the Qaidam Basin during the Serpukhovian.