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Close of the Cretaceous and opening of Eocene time in North America

H. F. OSBORN
1914 Geological Society of America Bulletin  
In introducing this symposium on a critical point in geologic time emphasis must first be laid on the fact that the Periods were defined dur ing the last century by European paleontologists, and that American events can be dated only by comparison of American with European faunas and floras, unless simultaneous and world-wide diastrophic move ments can be demonstrated to have occurred. The demarcation between the Cretaceous and the Eocene periods of Europe rested first on the work of Deshayes
more » ... work of Deshayes on the extinct molluscan fauna of the Paris basin. It gradually developed in definition and clear ness under Lyell, D'Orbigny, Mayer, and Eymar. Gradually also vertex brate reptiles and mammals entered into the problem, and the formations along the northern coast of Europe and Belgium, with their contained marine fossils, served to define the Mcestrichtien stage (Dumont, 1849), while in the north another late Cretaceous phase typified the Danien stage (Desor, 1846). According to Haug (1912), the Danien overlies the Mcestrichtien coneordantly, and thus closes the Cretaceous period. The fauna is purely marine and exclusively Cretaceous. Some authors also place the overlying M ontien in the Cretaceous. The Mcestrichtien as exposed in Belgium includes a rich reptilian fauna, which comprises several kinds of mosasaurs, great marine turtles, iguanodont dinosaurs, and their enemies, the carnivorous dinosaurs. This is our last view of the dinosaur life of Europe. The Mcestrichtien fauna has not been closely correlated up to the present time with an American fauna. According to Williston, it is subsequent to any known American mosasaur fauna, and this author regards the Mcestrichtien as a lower phase of the Danien. It is to be noted also that no late Cretaceous terres
doi:10.1130/gsab-25-321 fatcat:t22rjk2juzebvm62bq3t5yqjkm