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University of California Publications in Geology 



[Vol. 9 



dition reaching its extreme manifestation in Neophron. The distal 

 troehleae are weak and come to lie more nearly in the same right and 

 left plane instead of forming that strongly marked arch seen in birds 

 with prehensile feet, such as hawks and owls. The posterior face of 

 the shaft is less deeply excavated for the flexor tendons to the toes. 

 All these are characters indicative of reduction of prehensile power 

 in the foot. They are characters more or less noticeable in all vulturids 

 and they indicate roughly the degree of degeneracy from a more 

 aggressively raptorial type. Neophron, which is set off by some 

 writers from other vulturids, as constituting a distinct family, is 

 generally conceded to represent the extreme of this degeneracy and 

 it has the evidence of this degeneracy most indelibly stamped upon 

 the tarsometatarsus. Mainly because of the characters of this bone, the 

 Rancho La Brea species have been placed in new genera of these weak- 

 footed raptors, although in the case of Neoplirontops other bones of 

 the body less characteristic than the tarsometatarsus correspond with 

 those of the old-world Neophron. 



NEOPHEONTOPS AMEBIC ANUS, n. gen. and sp. 



Type specimen no. 22402, Univ. Calif. Col. Vert. Palae. From the asphalt 

 deposits of Eaneho La Brea. 



Tarsometatarsus. — The type is a perfect specimen, as well preserved 

 as though freshly macerated from the flesh. The ossification and the 

 distinctness of intermuscular lines indicate an individual of advanced 

 age. Other members of the series have smoother contours. The speci- 

 men of Neophron ginginianus available for comparison appears from 

 characters of the surface to be a slightly sub-adult bird. In general 

 proportions the two bones are almost identical, the ratio of shaft 

 diameter to length being .072 in Neoplirontops and .077 in Neophron. 

 When viewed from in front, the asphalt specimen is seen to have less 

 pronounced excavation about the papilla of the tibialis anticus. That 

 papilla is thus more prominent and is placed higher on the shaft. The 

 anterior openings of the proximal foramina are closer together. The 

 antero-external contour of the shaft is a little more prominent, as is 

 also the intermuscular line running from the papilla of the tibialis 

 anticus down the front of the shaft. These last two characters may 

 well be due to age in the individual. Distally the shaft widens more 

 gradually into the foot and the troehleae are narrower and weaker. 

 The troehleae are more nearly on the same level. 



