A Late Jurassic fossil assemblage in Gondwana: Biostratigraphy and correlations of the Tacuarembó Formation, Parana Basin, Uruguay

The Tacuarembó Formation has yielded a fossil assemblage that includes the best known body fossils, consisting of isolated scales, teeth, spines, and molds of bones, recovered from thin and patchy bonebeds, from the Botucatu Desert, Parana Basin, South America. The remains are preserved in the sandstones widespread around the city of Tacuarembó. We propose a new formalized nomenclature for the Tacuarembó Formation, naming its “Lower” and “Upper” members as the Batoví (new name) and Rivera (new rank) members, respectively. An assemblage zone is defined for the Batoví Member (fluviolacustrine and aeolian deposits). In this unit, the freshwater hybodontid shark Priohybodus arambourgi D’Erasmo is well represented. This species was previously recorded in Late Jurassic–Early Cretaceous units of the Sahara and the southern Arabian Peninsula. Globally considered, the fossil assemblage of this member (P. arambourgi, dipnoan fishes, Ceratosaurus-like theropods, and conchostracans) is indicative of a Kimmeridgian–Tithonian age, which in combination with the stratigraphic relationships of the Tacuarembó Formation with the overlying basalts of the Arapey Formation (132 My average absolute age) implies that the latter was deposited during the Kimmeridgian–Hauterivian interval.     

狼鳍鱼（Lycoptera）岩层的时代归属

在燕辽区，狭义的大北沟组产Ｎｅｓｔｏｒｉａ－Ｋｅｒａｔｅｓｔｈｅｒｉａ群，Ｅｏｐａ－ｒａｃｙｐｒｉｓ－Ｌｕａｎｐｉｎｇｅｌｌａ－Ｄａｒｗｉｎｕｌａ组合等化石，白旗组的Ｒｂ－Ｓｒ等时线年龄为１４５．２Ｍａ，以及完整的层序关系均证明狼鳍鱼岩层履于上侏罗统之上。热河动物群包括原始Ｔｒｉｇｏｎｉｏｉｄｉｄｓ群，Ｅｏｓｅｓｔｈｅｒｉａ群，Ｌｙｃｏｐｔｅｒａ群…以自身的演化规律阐明其属于白垩系的类群。Ｅｏｓｅ