Data from: Morphological diversification of ampullariid gastropods (Nsungwe Formation, late Oligocene, Rukwa Rift Basin, Tanzania) is coincident with onset of East African rifting

A new freshwater gastropod fauna is described from the late Oligocene Nsungwe Formation of the Rukwa Rift Basin, Tanzania. Six new species of ampullariids are established including five species of Lanistes (L. microovum, L. nsungwensis, L. songwellipticus, L. songweovum and L. rukwaensis) and one species of Carnevalea (C. santiapillai). These taxa occupy a morphospace region comparable to nearly half of extant Lanistes, a common and widespread genus in Africa and Madagascar. Palaeoecological evidence indicates that Nsungwe ampullariids inhabited fluvial, pond, and paludal environments. Among these species are the oldest high-spired and fluvially adapated Lanistes taxa. We suggest that Nsungwe Lanistes rapidly diversified in concert with habitat heterogeneity associated with the initiation of rifting along the Western Branch of the East African Rift System (EARS). Taxonomy, evolution and the biogeographic affinities of Nsungwe Formation freshwater gastropods contributes significantly to expanding the undersampled Palaeogene invertebrate fossil record of continental Africa.

本文记述了产自坦桑尼亚鲁夸裂谷盆地（Rukwa Rift Basin）渐新世晚期恩松圭组（Nsungwe Formation）的全新淡水腹足类动物群。本次研究建立了6个瓶螺科（Ampullariidae）新物种，包含5个Lanistes属物种（L. microovum、L. nsungwensis、L. songwellipticus、L. songweovum及L. rukwaensis）以及1个Carnevalea属物种（C. santiapillai）。这些类群的形态空间范围接近现生Lanistes属物种的半数，而Lanistes属是非洲及马达加斯加地区常见且广布的属类。古生态学证据显示，恩松圭组瓶螺类栖息于河流、池塘及沼泽环境中。在这些物种中，存在已知最古老的高旋且适应河流生境的Lanistes类群。我们认为，恩松圭组Lanistes属物种的快速辐射演化，与东非裂谷系统（East African Rift System, EARS）西部分支裂谷作用启动所带来的生境异质性紧密相关。本研究针对恩松圭组淡水腹足类的分类学、演化及生物地理亲缘关系展开探讨，将显著拓展非洲大陆古近纪无脊椎动物化石记录中采样不足的部分，为相关研究提供重要支撑。