Faunal response to sea-level and climate change in a short-lived seaway: Jurassic of the Western Interior, USA

Understanding how regional ecosystems respond to sea-level and environmental perturbations is a main challenge in palaeoecology. Here we use quantitative abundance estimates, integrated within a sequence stratigraphic and environmental framework, to reconstruct benthic community changes through the 13 myr history of the Jurassic Sundance Seaway in the western United States. Sundance Seaway communities are notable for their low richness and high dominance relative to most areas globally in the Jurassic, and this probably reflects steep temperature and salinity gradients along the 2000 km length of the Seaway that hindered colonization of species from the open ocean. Ordination of samples shows a main turnover event at the Middle–Upper Jurassic transition, which coincided with a shift from carbonate to siliciclastic depositional systems in the Seaway, probably initiated by northward drift from subtropical latitudes to more humid temperate latitudes, and possibly global cooling. Turnover w...理解区域生态系统对海平面变化与环境扰动的响应机制，是古生态学（palaeoecology）领域的核心挑战之一。本研究依托整合于层序地层学（sequence stratigraphic）与环境框架内的定量丰度估算数据，重建了美国西部侏罗纪桑丹斯海道（Sundance Seaway）1300万年演化历程中的底栖生物群落（benthic community）变化。相较于全球多数侏罗纪海域，桑丹斯海道的底栖生物群落以低物种丰富度与高优势度为显著特征，这一现象大概率反映了该海道全长2000千米范围内存在的急剧温度与盐度梯度——此类梯度阻碍了远洋物种向海道内的定植。样本排序分析（ordination）结果显示，侏罗纪中-晚侏罗世过渡期存在一次主要的群落更替事件；该事件与海道内沉积体系从碳酸盐岩向陆源碎屑岩的转变相吻合，而这一转变大概率由海道从亚热带纬度向北漂移至更湿润的温带纬度所引发，同时可能伴随全球变冷过程。此次群落更替……