Abstract Internal moulds of rudist bivalves from the basal Exu Formation of the western Araripe Basin, northeastern Brazil, are identified as the Early Cretaceous (Barremian to Aptian) radiolitidin caprinuloideid genus cf. Amphitriscoelus Harris and Hodson. The rudists occur as part of a sparse assemblage of remane fossils in the Exu Formation, a fluvial sandstone resting disconformably on the Santana Formation of the Araripe Group and are likely to have been derived from the shallow marine upper parts of that formation. The presence of caprinuloideid rudists in the Exu Formation suggests that the underlying Santana Formation can be no younger than lower Aptian. These are the first rudist bivalves found in Brazil and are the furthest south occurrence of caprinuloideid rudists, confirming suspected faunal links for the Araripe Basin with the Caribbean province of the Tethyan realm.

中文翻译：

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巴西有土匪！比较派生的例子。Amphitriscoelus Harris 和 Hodson，1922 年，在巴西东北部的阿拉里佩盆地：对桑塔纳和克拉托地层的 Lagerstätten 化石年代的影响

摘要 来自巴西东北部 Araripe 盆地西部 Exu 组基底的 rudist 双壳类动物的内部霉菌被鉴定为早白垩世（巴雷米阶到阿普阶）radiolididin caprinuloideid 属 cf. Amphitriscoelus Harris 和 Hodson。这些 rudists 是 Exu 组中稀有的残骸化石组合的一部分，这是一种不整合地位于 Araripe 组的 Santana 组上的河流砂岩，很可能来自该组的浅海相上部。Exu 组中山羊属的存在表明下伏的 Santana 组可能不比下 Aptian 年轻。这些是在巴西发现的第一个双壳类双壳类动物，也是最南端的双壳类双壳类动物，