Data from: Recovery of benthic marine communities from the end-Permian mass extinction at the low-latitudes of Eastern Panthalassa

Based on the quantitative community analysis using species-level identifications, we track the restoration of benthic ecosystems after the end-Permian mass extinction throughout the Lower Triassic of the western USA. New data on the palaeoecology of the Thaynes Group and Sinbad Formation are provided, which fill a gap between the recently studied palaeoecology of the Griesbachian–Dienerian Dinwoody Formation and the Spathian Virgin Formation. In the Sinbad Formation and Thaynes Group, 17 species (12 genera) of bivalves, 7 species and genera of gastropods and 2 species and genera of brachiopods are recognized. The new bivalve genus Confusionella (Pteriidae) is described. A comprehensive review of the whole Lower Triassic succession of benthic ecosystems of the western USA indicates that mid- and inner shelf environments show incipient recovery signals around the Griesbachian–Dienerian transition, during the Smithian and, most profound, during the early Spathian. Ecological data from youngest strata of the Dinwoody Formation as well as stratigraphic ranges of species suggest that the late Dienerian was likely a time interval of environmental stress for benthic ecosystems. Despite some evidence for short-term environmental disturbances (e.g. shift of dominant taxa, transient drop in alpha-diversity) during the Smithian–Spathian transition, benthic ecosystems did not show any notable taxonomic turnover at that time, in contrast to the major crisis that affected ammonoids and conodonts. Whereas alpha-diversity of benthic communities generally increased throughout the Early Triassic, beta-diversity remained low, which reflects a persistently wide environmental range of benthic species. This observation is in accordance with a recently proposed model that predicts a time lag between increasing within-habitat diversity (alpha-diversity) and the onset of taxonomic differentiation between habitats (beta-diversity) during biotic recoveries from mass extinction events. The observation that beta-diversity had not significantly increased during the Early Triassic might also provide an explanation for the comparably sluggish increase in benthic diversity during that time, which has previously been attributed to persistent environmental stress.

本研究基于物种级鉴定的定量群落分析，追踪了美国西部下三叠统（Lower Triassic）地层中二叠纪末大灭绝（end-Permian mass extinction）后底栖生态系统（benthic ecosystems）的复苏进程。本文提供了泰恩斯群（Thaynes Group）与辛巴德组（Sinbad Formation）古生态学（palaeoecology）的新数据，填补了此前已研究的格里斯巴赫期-第聂兰期（Griesbachian–Dienerian）迪伍迪组（Dinwoody Formation）与斯帕斯期维尔京组（Spathian Virgin Formation）古生态学之间的研究空白。在辛巴德组与泰恩斯群中，共识别出双壳类（bivalves）17种（隶属于12属）、腹足类（gastropods）7属7种，以及腕足类（brachiopods）2属2种。本文还描述了全新双壳类属混淆蛤属（Confusionella，珍珠贝科（Pteriidae））。对美国西部下三叠统全部底栖生态系统地层序列的综合回顾显示，陆棚环境（shelf environments）中、内带在格里斯巴赫期-第聂兰期过渡期、史密斯期（Smithian），以及最为显著的斯帕斯早期（early Spathian）均显现出初始复苏信号。来自迪伍迪组最年轻地层的生态学数据，以及物种的地层延限范围均表明，第聂兰晚期可能是底栖生态系统遭受环境压力的一段时期。尽管在史密斯期-斯帕斯期（Smithian–Spathian）过渡期存在短期环境扰动的相关证据（如优势类群更替、α多样性（alpha-diversity）短暂下降），但底栖生态系统彼时并未出现显著的分类学更替，这与影响菊石（ammonoids）与牙形石（conodonts）的重大危机形成鲜明对比。尽管底栖群落的α多样性整体在早三叠世呈上升趋势，但β多样性（beta-diversity）始终处于较低水平，这反映出底栖物种的环境分布范围持续宽泛。这一观测结果与近期提出的生物复苏模型相符：该模型预测，在大灭绝事件后的生物复苏过程中，生境内多样性（α多样性）的提升与生境间分类分化（β多样性）的启动之间存在时间滞后。早三叠世期间β多样性未出现显著提升这一观测结果，或许也能解释彼时底栖多样性增长相对缓慢的现象——此前该现象被归因于持续存在的环境压力。