The effect of siliceous sponge deposition on Permian paleocommunity structure

A dramatic shift from carbonate-rich to chert-rich marine strata occurred during the Permian and is frequently attributed to the increased activity of siliceous sponges and their biosiliceous sedimentation. The first-order ecological consequences of this transition, if any, remain opaque. We analyze fossil occurrence data from the Phosphoria Basin (western North America) to test whether the presence of siliceous sponges, which are correlated with basin-wide chert strata, influenced the recruitment of benthic fauna. We digitized occurrence data from Yochelson and Van Sickle (1968), with particular attention to 228 fossil collections with detailed lithologic descriptions. We categorized fossil collections by formation, facies, and lithology, and used these data to code DCA and NMDS ordinations. We also analyzed the clustering of taxa into faunal units termed biofacies. Results from these analyses indicate that fossil collections occurring in chert and carbonate are closely associated in f...二叠纪期间，富碳酸盐岩海相地层向富燧石海相地层发生了显著转变，这一现象通常被归因于硅质海绵（siliceous sponges）活动的增强及其生物硅质沉积作用（biosiliceous sedimentation）。此次转变所带来的一级生态效应（若存在）迄今仍不明确。本研究针对北美西部磷海盆（Phosphoria Basin）的化石产出数据展开分析，以验证与全盆域燧石地层相关的硅质海绵的存在是否会对底栖生物群（benthic fauna）的种群补充产生影响。我们对Yochelson与Van Sickle（1968）的化石产出数据进行了数字化处理，重点关注其中228份带有详细岩性描述的化石标本集合。我们依据地层组、沉积相以及岩性对这些化石标本集合进行分类，并基于该数据对去趋势对应分析（DCA）与非度量多维尺度分析（NMDS）的排序结果进行编码。此外，我们还分析了分类群聚类为被称为生物相（biofacies）的动物群单元的过程。上述分析结果表明，产自燧石与碳酸盐岩地层的化石标本集合在f...中存在紧密关联。