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.

中文翻译：

---

来自西澳大利亚珀斯盆地的早三叠世微螺类：二叠纪末大灭绝后的古生态学和繁盛

Microconchids是与螺旋藻多毛纲会聚的小型螺旋蠕虫管，它们在分类学和时空分布方面不是众所周知的化石群。在这里，我们首次报告了微海螺物种Microconchus cf。utahensis来自西澳大利亚珀斯盆地的下三叠纪钻孔剖面，在二叠纪-三叠纪 (P-Tr) 过渡期间位于冈瓦纳内陆内海。新发现的微型海螺包裹着双壳类Claraia贝壳，这些贝壳以贝壳床的形式出现在珀斯盆地钻孔的岩心样本中。这些微型海螺，连同Claraiaspp.，形成一个高丰度、低多样性的组合，它们生活在一个浅的、受限的内海中，具有富氧到缺氧的氧化还原条件。这些微小的结壳生物在缺氧的栖息地繁衍生息，在那里其他底栖生物非常罕见。它们代表了 P-Tr 大灭绝之后的灾难形式。三叠纪微海螺的全球数据集显示，该进化枝栖息在从大陆盆地、近岸、受限浅海、受限内台、开放平台到陆架和盆地的广泛环境中，所有这些都是当时的缺氧环境。在地理上，微海螺广泛分布于低纬度地区（即古特提斯东部的华南、古特提斯西部、新特提斯、西海岸、和泛海环礁）以及早三叠世期间北部和南部的中高纬度地区（即分别是北方海域的格陵兰岛和冈瓦纳大陆的珀斯盆地）。微海螺的时空分布表明，随着 P-Tr 灭绝，灾害生物的繁盛。体型小和对环境压力的高耐受性促使微海螺在三叠纪取得成功。