CAIMANOIDEA VISHERI, A NEW CROCODILIAN FROM 

 THE OLIGOCENE OF SOUTH DAKOTA 



MAURICE G. MEHL 



University of Wisconsin 



In the summer of 191 1, Mr. S. S. Visher, then connected with 

 the Geological Survey of South Dakota, collected some interesting 

 crocodilian material from the Oligocene of Washington County, 

 South Dakota. Some time ago, the attention of the writer was 

 called to these remains by Dr. Visher, and recently through the 

 courtesy of Mr. W. H. Over, director of the museum at the Uni- 

 versity of South Dakota, the collection was loaned to the writer 

 for study. 



The material herein described consists of a goodly portion of 

 a skull, a nearly complete mandible, two femora and other limb 

 bones, a nearly complete series of vertebrae, many dorsal scutes, 

 and numerous fragments. According to Dr. Visher, the collection 

 was made from the Titanothere zone of the Lower White River 

 beds, perhaps 20 to 30 feet above their base. 



THE SKULL 



Of the skull, nearly the entire right half is preserved as well 

 as portions from the left side including the quadrate region, the 

 posterior half of the cranium roof from the median line to the middle 

 of the orbit and supratemporal vacuity, and fragments of the 

 maxilla along the alveolar margin. Of the base of the skull but 

 little remains save the separate occipital condyle and portions of 

 the exoccipitals. 



In general shape and appearance it is quite similar to that of 

 the alligators. A lateral expansion of the maxilla in the region of 

 the third to fifth maxillary teeth produces a marked break in the 

 otherwise regular outline of the muzzle, more prominent, perhaps, 

 than in most of the Crocodilia. The width of the skull in the 

 region of this maxilla expansion is 72 mm. Immediately back 



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