Marine benthic communities in the Early Carboniferous of New South Wales (Visean-Delepinea aspinosa Zone)

The Delepinea aspinosa brachiopod Zone comprises two subzones: the Inflatia elegans and Linoprotonia tenuirugosa Subzones. Multivariate (cluster) analysis is used to identify benthic marine fossil communities (recurrent species associations) in samples collected from all known fossiliferous intervals of these subzones in the study area. The Euclidean distance coefficient, a weighted-pair grouping method, and a standardised data set are used to form dendrographic clusters inferred to represent recurrent species associations (communities). The results parallel those from faunas of the succeeding Rhipidomella fortimuscula Zone, i.e. several communities are evident and some species are numerically significant in more than one community. The communities of each subzone appear to intergrade rather than form rigid, depth-limited assemblages. Faunas of the I. elegans Subzone cluster into four communities, including the Unispirifer striatoconvolutus community, present in substrates near or below wave-base on a marine shelf. The I. elegans community is closest in species composition to the U. striatoconvolutus community, but does not occupy the same geographic range; it may be a precursor community. Two other communities, the Rhipidomella australis and Leptagonia analoga communities, overlap in range with the first two communities and are inferred to have occurred in a mid-shelf setting. Faunas of the subsequent faunal assemblage, the Linoprotonia tenuirugosa Subzone, are present on marine shelf substrates influenced by an actively prograding shoreline. The Rhipidomella australis community persisted into this subzone with a modified species composition. The Rugosochonetes careyi community is a new element.

无刺德列平贝（Delepinea aspinosa）腕足类（brachiopod）带包含两个亚带：优雅Inflatia（Inflatia elegans）亚带与细皱前岭贝（Linoprotonia tenuirugosa）亚带。本研究采用多变量聚类分析，对采自研究区内上述两个亚带所有已知含化石层位的样品进行分析，以识别其中的底栖海洋化石群落，即重复出现的物种组合。研究采用欧氏距离系数、加权配对分组法以及标准化数据集，构建了树状聚类图，该图被推断代表了重复出现的物种组合，即化石群落。本研究结果与后续的强壮扇房贝（Rhipidomella fortimuscula）带的动物群研究结果相吻合：即存在多个明确的群落，且部分物种在不止一个群落中具有显著的数量占比。
各亚带的群落似乎呈现过渡特征，而非形成严格受深度限制的组合。优雅Inflatia亚带的动物群可聚类为四个群落，其中包括卷积单脊贝（Unispirifer striatoconvolutus）群落，该群落分布于海洋陆架上近浪基面或浪基面以下的基底环境。优雅Inflatia群落的物种组成与卷积单脊贝群落最为相近，但二者的地理分布范围并不重叠；前者可能是后者的前驱群落。另外两个群落——南方扇房贝（Rhipidomella australis）群落与类似薄皱贝（Leptagonia analoga）群落，其分布范围与前两个群落存在重叠，被推断形成于陆架中部环境。
后续的动物群组合即细皱前岭贝亚带的动物群，发现于受活跃进积岸线影响的海洋陆架基底环境。南方扇房贝群落延续至该亚带，但其物种组成发生了改变。凯里皱孔贝（Rugosochonetes careyi）群落为该亚带新增的类群。