Article XII.— ORNITHOLESTES HERMANNI, A NEW 



COMPSOGNATHOID DINOSAUR FROM THE 



UPPER JURASSIC. 



By Henry Fairfield Osborn. 



The type skeleton (Amer. Mus. Coll. No. 619) of this re- 

 markable animal was discovered at Bone Cabin Quarry, near 

 Medicine Bow, Wyoming, by the American Museum Expedi- 

 tion of 1900. It was removed and transported to the 

 Museum with the greatest care, and worked out, restored, and 

 mounted under the direction of the head preparator, Mr. 

 Adam Hermann, in recognition of whose many services .to 

 vertebrate palaeontology the species is named. 



The material embraces: the skull; 45 vertebrae, including 

 3 cervicals, 11 dorsals, a complete sacrum, 27 caudals; 

 the complete pelvic girdle; representative portions of both 

 fore and hind limbs, — all belonging to one individual; our 

 knowledge of the manus is chiefly derived from another 

 specimen (Amer. Mus. Coll. No. 587). 



Principal Characters. 



The entire length of the skull and vertebral column as re- 

 stored is 2.22 m. (7 ft. 3^ in.); the height at the pelvis is 

 .56 m. (22 in.). 



The vertebral formula, except in the sacrum, is still unde- 

 termined. 



The most distinctive feature is the narrowing of the manus 

 and the great elongation (.172 m.) of the metapodials and 

 phalanges of the second digit, suggesting the rapid grasping 

 power of agile and delicate prey. This feature, combined 

 with the prehensile character of the somewhat enlarged an- 

 terior teeth, the extreme lightness of the skeleton, the cur- 

 sorial structure of tlie hind limbs, tlic balancing power of the 

 tail, suggest the hypothesis that the animal may have been 

 adapted to the pursuit of the Jurassic birds; in allusion to 

 this supposed habit the genus may be named Ornitholestes, or 

 'bird robber,' as suggested by Dr. Theodore Gill. 



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