Early Triassic microconchids from the Perth Basin, Western Australia: Palaeoecology and flourishing in the aftermath of the end‐Permian mass extinction. (4th March 2021)

• Record Type: Journal Article
• Authors: Yang, Hao; Chen, Zhong‐Qiang; Mei, Xi; Sun, Yadong
• Other Names: Chen Zhong‐Qiang guestEditor.; Wang Xiangdong guestEditor.; Cao Cangqun guestEditor.; Luo Mao guestEditor.
• Is Part Of: Geological journal. Volume 56:Number 12(2021)
• Page Start: 6210
• Page End: 6222
• Publication Date: 2021-03-04
• Subjects: disaster taxa -- end‐Permian mass extinction -- euxinic to anoxic conditions -- inland Gondwana -- worm tube; Geology -- Periodicals; 551
• DOI: 10.1002/gj.4115
• Languages: English
• ISSNs: 0072-1050

Abstract

Abstract : Microconchids are small spiral worm tubes convergent with spirorbin polychaetes, and they are not a well‐known fossil group in terms of taxonomy and spatiotemporal distributions. Here, we report for the first time microconchid species Microconchus cf. utahensis from the Lower Triassic borehole sections in the Perth Basin, Western Australia, which were situated in the interior sea of inland Gondwana during the Permian–Triassic (P–Tr) transition. The newly found microconchids encrust bivalve Claraia shells, which occur in the forms of shell beds in core samples of boreholes in the Perth Basin. These microconchids, together with Claraia spp., form a high‐abundance, low‐diversity assemblage, which lived in a shallow, restricted interior sea, with euxinic to anoxic redox conditions. These tiny encrusting organisms flourished in the oxygen‐poor habitats, where other benthos was very rare. They represent disaster forms in the aftermath of the P–Tr mass extinction. Global dataset of the Triassic microconchids shows that this clade inhabited a wide range of environments from continental basins, nearshore, restricted shallow sea, restricted inner platform, open platform, to shelf and basin, all of which were oxygen‐limited settings in that time. Geographically, microconchids were widespread in the low‐latitude regions (i.e., South China of eastern Palaeo‐Tethys, western Palaeo‐Tethys, Neo‐Tethys, western coasts, and atolls of the Panthalassic Ocean) and to northern and southern moderate‐high latitude regions (i.e., Greenland of Boreal seas and Perth Basin of inland Gondwana, respectively) during the Early Triassic. The spatiotemporal distributions of microconchids suggest the flourishing of disaster organisms following the P–Tr extinction. Both small body size and high tolerance to environmental stresses promoted microconchids to succeed in the Triassic.