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MATTHEW— THE OSTEOLOGY OF SINOPA. 69 



NOTES ON THE OSTEOLOGY OF SINOPA, A PRIMI- 

 TIVE MEMBER OF THE HY.LNODONTIDtE. 



BY W. D. MATTHEW. 



( Read April /j, igoj. ) 



The following observations are based upon a nearly complete 

 skeleton of a Middle Eocene creodont discovered by Mr. Walter 

 Granger near Fort Bridger, Wyo., in 1902. The specimen is the 

 property of the National Museum and the full description will be 

 published under the auspices of that institution. I am indebted 

 to the Secretary of the Smithsonian Institution for permission to 

 publish this abstract in advance. 



The skeleton is unusually well preserved, and practically complete 

 except for the feet. Most of one fore and one hind foot are pre- 

 served, the others are missing. It is believed to be one of the most 

 perfect skeletons ever found in this formation and is of interest as a 

 typical generalized Creodont. The points of especial interest in its 

 study were : (1) the relations of the Creodonta to marsupials and 

 Insectivora, and (2) the relations of Sinopa to Hycenodon and to the 

 Oxysenidae. 



Sinopa was the first fossil carnivore described from the Eocene 

 of North America and is a characteristic genus of the Lower and 

 Middle Eocene found in Europe as well as in this country. The 

 dentition of this or allied genera has been well known from the 

 descriptions of Cope and Scott, and Wortman in 1902 described a 

 skull and some parts of the skeleton which he referred to Sinopa. 

 The complete knowledge of the skeleton enables us to determine 

 its relationships with certainty, and for the most part confirms the 

 views hitherto generally accepted. 



The animal was a little smaller than a coyote, but in proportions 

 much more like the Tasmanian wolf, the lower limbs and feet being 

 much shorter and less compact than in any of the Canidse, and the 

 tail long and heavy. The skull is long both in cranial and facial 

 regions, the long basicranial region being very characteristic of 

 carnivora, while in marsupials and insectivores the basicranial region 

 is short. The mastoid has a small exposure on the side of the 



