Paleotemperature Analyses of Mesozoic Belemnoidea from Germany and Poland

Specimens of Jurassic and Cretaceous Belemnoidea were analyzed and their paleotemperature record compiled from mass-spectrometric measurements. The data are compared with information assembled from other fields of investigation. It is demonstrated that from a subtropical climate in the later Jurassic, a more diversified one developed in the Cretaceous. From the rather cool conditions of the Neocomian, a temperature climax was reached in Albian times-to be followed by a decline attaining its minimum in Cenomanian waters. Later, another temperature climax occurred-in the Coniacian-Santonian. Subsequently, a gradual lowering of temperature took place during the Campanian and was succeeded by cool, stable conditions in the Maestrichtian. This picture of Cretaceous climatic change was derived from the analyses of Mesozoic material from Germany and Poland described in detail in the present paper and supplemented by examination of additional specimens from western Europe. It is possible that the late Cretaceous temperature decline was instrumental in the extinction of the poikilothermous dinosaurs. It is apparent that the pole shifted in relation to Europe during the Mesozoic, but its position is not yet determined.