Early Triassic microconchids from the Perth Basin, Western Australia: Palaeoecology and flourishing in the aftermath of theend‐Permianmass extinction

Abstract

Handling Editor: M. Luo 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.

Adaptive function and phylogenetic significance of novel skeletal features of a new Devonian microconchid tubeworm (Tentaculita) from Wyoming, USA

“…They were also a common constituent of microbial buildups (Peryt, 1974; Burchette and Riding, 1977; Toomey and Cys, 1977; Dreesen and Jux, 1995; He et al, 2012) and metazoan buildups (Pruss et al, 2007; Brayard et al, 2011), and in some cases formed their own bioherms (Beus, 1980; Wilson et al, 2011; Zatoń et al, 2018). Microconchids are the dominant, or even sole, encrusters in the aftermaths of some of the mass extinctions, and thus they are widely considered as an opportunistic, ‘disaster’ taxon (Fraiser, 2011; Zatoń and Krawczyński, 2011a; He et al, 2012; Yang et al, 2015, 2021; Zatoń et al, 2016a; Shcherbakov et al, 2021).…”

Late Palaeozoic‐Mesozoic palaeontology and stratigraphy in China: A tribute to the achievements of Professor Zhuoting Liao

“…In addition, H. Yang et al (2021) report abundant well‐preserved microconchids from the Lower Triassic borehole sections in the Perth Basin, Western Australia. Similar microconchids have also been found to be commonly present in various habitats over the P‐Tr transition, that is, brachiopod shells (Z. T. Liao, 1982a) and bivalve shells (Z. Q. Chen, Tong, et al, 2009a).…”

“…Four papers focus on biotic, palaeoecological, and environmental variations across the Permian–Triassic (P‐Tr) boundary (Cui & Cao, 2021; Miao et al, 2021; Sun et al, 2021; H. Wu, Zhang, & Sun, 2021). Two papers (X. Shi, Lang, et al, 2021; H. Yang, Chen, Mei, & Sun, 2021) and one paper (Z. Ma, Hu, et al, 2021) concerns the Early Triassic palaeoecology and Middle Triassic palaeoenvironments, respectively. One paper attempts to reconstruct the Early Jurassic palaeoclimate regime based on palaeoecological analysis of dinosaur fossils ( H. Shen et al , 2021), and another documents the middle Campanian (Cretaceous) shallow marine red beds, which are coeval with the typical “Cretaceous oceanic red beds (CORBs)” from elsewhere in the world.…”

“…Six and seven papers address sedimentary and palaeontology of Guangxi and northern Xinjiang Province, respectively (F. Chen, Xue, et al, 2021; Cui & Cao, 2021; Z. Guo, Chen, Harper, & Huang, 2021; W. Guo, Nie, Lu, et al, 2021; X. Huang, Wang, et al, 2021; Q. Ma, Ye, et al, 2021; X. Shi, Lang, et al, 2021; T. M. Shi, Li, et al, 2021; Song et al, 2021; Wan et al, 2021; Wang F. et al, 2021; Wei et al, 2021; Zong et al, 2021; Figure 1). Outside China, two papers document fossil materials from Western Australia and Malaysia, respectively ( Tang et al , 2021; H. Yang et al , 2021).…”

“…Regional distribution of 30 papers assembled in the present special volume. Codes for contributions assembled in this volume: 1 = M. Wang, Guo, et al (2021); 2 = Q. Chen, Chen, et al (2021); 3 = H. Wang, Lei, et al (2021); 4 = W. Guo, Nie, Lu, et al (2021); 5 = Bai et al (2021); 6 = Qiao et al (2021); 7 = Song et al (2021); 8 = Zong et al (2021); 9 = Yao et al (2021); 10 = W. Guo, Nie, Lu, et al (2021); 11 = Tang et al (2021); 12 = Shi et al (2021); 13 = Mao et al (2021); 14 = X. Huang, Wang, et al (2021); 15 = F. Chen, Xue, et al (2021); 16 = Q. Ma, Ye, et al (2021); 17 = Wei et al (2021); 18 = Ding et al (2021); 19 = Wan et al (2021); 20 = Wang, Yao, & Wang (2021); 21 = Cui and Cao (2021); 22 = Miao et al (2021); 23 = H. Wu et al (2021); 24 = Sun et al (2021); 25 = H. Yang et al (2021); 26 = Shi et al (2021); 27 = Z. Ma, Hu, et al (2021); 28 = H. Shen et al (2021); 29 = Y. W. Li et al (2021); 30 = Lan et al (2021)…”