Darriwilian Saucrorthis Fauna: implications for the Great Ordovician Biodiversification Event (GOBE); pp. 323–328

B Huang,G Wang,R Zhan,X Luan,Y Liang,Y Wang

doi:10.3176/earth.2014.38

Abstract

The Saucrorthis Fauna is a brachiopod-dominated shelly fauna developed in relatively deeper-water benthic regimes of a few peri-Gondwana terranes (e.g. northern Iran) and palaeoplates (South China and Sibumasu) during the Darriwilian (late Middle Ordovician). It has its longest geological range, widest palaeogeographic distribution, most abundant and diversified brachiopod taxonomic composition and most complex palaeoecological differentiation in South China, where it concentrated in the centre of the Upper Yangtze Platform. The generally low similarity coefficients (< 0.3) between any two representatives of the Saucrorthis Fauna firmly support a statement about the Great Ordovician Biodiversification Event (GOBE) that strong endemism or provincialism made a great contribution to the second pulse of the Ordovician brachiopod radiation in South China, which might also be true for the international trend.

Highlights

The Darriwilian Saucrorthis Fauna is a brachiopod-dominated normal marine shelly fauna characterized by the small- to medium-shelled, costate eponymous genus and the predominance of some common orthides (e.g. Orthambonites and Parisorthis) and strophomenides (e.g. Leptellina, Calyptolepta and Bellimurina) (Fig. 1)
The genus Saucrorthis of the subfamily Productorthinae was named 40 years ago from the calcareous mudstone of the Shihtzupu Formation (Darriwilian) at Shizipu of Zunyi, northern Guizhou Province, southwest China (Xu et al 1974), but the Saucrorthis Fauna as a whole was first recognized by Zhan et al (2007) as a unique benthic shelly fauna representing the second diversity acme of the Ordovician brachiopod radiation in South China
Saucrorthis is known to be widely distributed on the Upper Yangtze Platform of the South China palaeoplate, and at some localities in the Shan States (Myanmar, Sibumasu palaeoplate) and the Alborz Mountains, but the taxonomic composition of the Saucrorthis Fauna at different localities varies substantially

Summary

Introduction

The Darriwilian (late Middle Ordovician) Saucrorthis Fauna is a brachiopod-dominated normal marine shelly fauna characterized by the small- to medium-shelled, costate eponymous genus and the predominance of some common orthides (e.g. Orthambonites and Parisorthis) and strophomenides (e.g. Leptellina, Calyptolepta and Bellimurina) (Fig. 1). The genus Saucrorthis of the subfamily Productorthinae was named 40 years ago from the calcareous mudstone of the Shihtzupu Formation (Darriwilian) at Shizipu of Zunyi, northern Guizhou Province, southwest China (Xu et al 1974), but the Saucrorthis Fauna as a whole was first recognized by Zhan et al (2007) as a unique benthic shelly fauna representing the second diversity acme of the Ordovician brachiopod radiation in South China.

Results

Conclusion