Newly Reported Borealosuchus (Crocodylia, Eusuchia) from the Camels Butte Member (Eocene) Golden Valley Formation of North Dakota

PERSON, Jeff J.; North Dakota Geological Survey, Bismarck, ND


Five genera of brevirostrian crocodylians have been reported from the Golden Valley Formation of North Dakota. Large osteoderms recovered from a locality within the Camels Butte Member (Wasatchian North American Land Mammal Age, Eocene) of the Golden Valley Formation in southwest North Dakota indicate the presence of a large crocodyliform.  No large crocodylian teeth or skull material that could pertain to this animal have been identified from this locality. One well preserved and nearly complete dorsal osteoderm has characters which indicate the presence of Borealosuchus. These characters include: 1) presence of anterolateral process, 2) no keel present, 3) rectangular in shape, 4) a smooth anterior surface, and 5) sutures on lateral surfaces. Borealosuchus wilsoni has been previously reported from Wyoming, Utah, and Colorado. The combination of the morphology, geologic age, and size of the osteoderms permits a referral to Borealosuchus cf. wilsoni. This report from North Dakota greatly increases the paleogeographic range of this species.