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.

本研究记述了产自坦桑尼亚鲁夸裂谷盆地渐新世晚期恩松韦组的一套全新淡水腹足类动物群。共确立瓶螺科（Ampullariidae）6个新物种，包括5个瓶螺属（Lanistes）物种：L. microovum、L. nsungwensis、L. songwellipticus、L. songweovum及L. rukwaensis，以及1个卡内瓦螺属（Carnevalea）物种：C. santiapillai。这些类群占据的形态空间范围近乎覆盖现生瓶螺属物种的一半——该属是非洲及马达加斯加地区常见且广布的类群。古生态学证据表明，恩松韦组瓶螺类栖息于河流、池塘及沼泽环境中。其中部分物种是已知最古老的高旋壳且适应河流生境的瓶螺属类群。我们推测，伴随东非裂谷系（EARS）西支裂谷作用启动所带来的生境异质性增加，恩松韦组瓶螺属类群发生了快速辐射演化。本研究对恩松韦组淡水腹足类的分类学、演化及生物地理亲缘关系的探讨，极大丰富了非洲大陆古近纪无脊椎动物化石记录这一研究不足的领域。