Brachiopods Near the Permian-Triassic Boundary in South China

Abstract

Sixty-eight genera and 164 species in the Changxingian Stage and 12 genera and 20 species in the lower Griesbachian Stage are recorded on the basis of brachiopod fossils collected from 32 sections in South China and from review of the Chinese literature. Of these, 24 genera and 34 species are described here, including three new genera (<i>Fanichonetes, Prelissorhynchia</i>, and <i>Rectambitus</i>) and 24 new species (<i>Acosarina strophiria, Enteletes asymmatrosis, Peltichia schizoloides, Derbyia pannuciella, Perigeyerella altilosina, Chonetinella cursothonia, C. volitanliopsis, Fanichonetes campigia, Cathaysia spiriferoides, Uncinunellina multicostifera, Prelissorhynchia triplicatioid, Cyrolexis antearcus, Cyrolexis beccojectus, Cartorhium xikouensis, C. twifurcifer, Callispirina rotundella, Araxathyris subpentagulata, A. beipeiensis, Spirigerella discsella, S. ovaloides, Squamularia formilla, Hustedia orbicostata, Rostranteris ptychiventria</i>, and <i>Notothyris bifoldes</i>). The <i>Cathaysia chonetoides-Chonetinella substrophomenoides</i> assemblage zone and the <i>Cathaysia sinuata-Waagenites barusiensis</i> assemblage zone represent respectively faunas of the lower Changxingian and the upper Changxingian in clastic lithofacies; whereas the <i>Peltichia zigzag-Prelissorhynchia triplicatioid</i> assemblage zone and the <i>Spirigerella discusella-Acosarina minuta</i> assemblage zone represent faunas in limestone lithofacies. The <i>Crurithyris pusilla-Lingula subcircularis</i> assemblage zone and Permian-type brachiopods are present in the lower Griesbachian. The Changxingian brachiopod fauna can be correlated with the Dorashamian fauna of Armenia; the brachiopod faunas of the Ali Bashi Formation, North-West Iran; unit 7 of the Hambast Formation, Central Iran; and the upper part of the <i>Bellerophon</i> Formation of the Southern Alps. The genera <i>Cathaysia, Peltichia</i>, and <i>Prelissorhynchia</i> are especially characteristic of the Cathaysia Tethyan Subprovince. In contrast, the West Tethyan Subprovince is characterized by the genera <i>Costiferina, Ombonia, Comelicania</i>, and many other species. Four brachiopod ecofacies are recognized in the Changxingian of South China: (1) antibiohermal dwellers; (2) calcareous substratum dwellers; (3) biohermal dwellers; and (4) ubiquitous substrate dwellers. In the lower Griesbachian, the brachiopod fauna of <i>Lingula</i> and <i>Crurithyris</i> spreads across the entire Tethys and is called the Circum-Pangaea brachiopod fauna. Massive extinction of brachiopod faunas occurred at the close of the Changxingian, with only a few Permian-types surviving into the early Griesbachian, and they completely vanished after the early Griesbachian except for harbingers of Mesozoic brachiopods.