THE OCCURRENCE OF A SAUROPOD DINOSAUR IN THE 

 TRINITY CRETACEOUS OF OKLAHOMA 



PIERCE LARKIN 



Oklahoma Geological Survey 



WITH AN INTRODUCTORY NOTE BY S. W. WILLISTON 

 Recently, during a visit to Norman, Oklahoma, Professor Gould, 

 director of the State Geological Survey, called my attention to a 

 large fossil bone which had lately been discovered in the Trinity 

 Cretaceous of that state by Mr. Pierce Larkin of the survey. This 

 specimen, clearly a morosaurian coracoid, furnishes the first indis- 

 putable evidence of the occurrence of the sauropod dinosaurs in the 

 Cretaceous of western America. At my suggestion Mr. Larkin has 

 prepared the following brief description of the Trinity deposits 

 of Oklahoma, giving the precise horizon of the fossil. The precise 

 taxonomic location of the specimen is not possible, since generic 

 characters are not well displayed in the coracoids of the dinosaurs, 

 and because of the partial mutilation of the specimen as it occurred 

 in its matrix. Excellent figures of the specimen, furnished by Pro- 

 fessor Gould, will render unnecessary a detailed description of the 

 bone. The occurrence of the Sauropoda in the Lower Cretaceous 

 is of course to be expected, since the recent discovery of similar 

 remains in the Upper Cretaceous of Africa. I have long believed that 

 the Morrison beds of the west are, in part at least, equivalent in age 

 to the Comanche Cretaceous of the interior. — S. W. Williston. 



The Trinity division of the Cretaceous of Texas contains three 

 distinct formations, the Travis Peak, the Glen Rose, and the Paluxy. 

 The Travis Peak and Paluxy are sand members, while the Glen 

 Rose is calcareous. Toward the north this formation loses its dis- 

 tinctive characteristics and merges gradually into the sandy members 

 above and below until one part of the Trinity cannot be distinguished 

 from another. Throughout northern Texas and Oklahoma there is 

 practically no change which could be made use of in separating 



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