92 



EDENTATA 



The skull and the massive extremities are very similar to those of the 

 Gh'avigrada. The primitive dentition, also, may very readily have given rise to 

 that of the Gravigrada. The slight difficulty in tracing this line of descent, 

 which lies in the fact that the Gravigrada occur already in the early 

 Tertiary of Patagonia, is surmounted if we assume that only the species of 

 the Torrejon beds are ancestral to the South American forms, and that 

 those of the Wasatch and Bridger formations became extinct without leaving 

 any descendants. The Taeniodontae possibly have a common origin with 

 the Tillodontidae, a family here placed among the Insectivores. 



The humerus is stout and provided with a well-developed deltoid crest 

 and entepicondylar foramen. The thick ulna has a high olecranon. The 

 form and mode of articulation of the carpals, metacarpals and phalanges 

 closely agree with those of the Gravigrada, especially Mylodon, as does 

 also the flattened ilium. . Only the astragalus diff'ers markedly on account of 

 its primitive form — i.e., having a long neck — from that of the Gravigrada. 

 The gradual increase in accessory vertebral articulation, however, helps 

 to establish their close relationship. 



2n. 4-3.3. 



Subfamily 1. Conoryctinae. 

 SkuU long, loio and with sagittal crest. Lower jaw elongated, and 



the articulation not much higher than the top of the teeth. I small, C long, P ^ and 



F ^ not placed transversely. Upper 

 M trit'ul)ercular, lower tvith four or 

 five cusps, and talonid sometvhat 

 lower than the trigonid. All- the 

 teeth are hracliyodont and rooted. 

 The croiim of the teeth is rapidly 

 worn down. 



Onychodectes Cope. ^ P, 

 lower il/ with paraconid. Lower 

 Eocene ; Puerco formation of 

 New Mexico. 



Conoryctes Cope (Fig. 114). 

 f P. M^ very small, lower M 





Fig. 114. 



■"^ Conoryctus cotuma Cope. Lower Eocene of Torrejon beds, New 

 Mexico. A, Skull and lower jaw. B, Lower dentition. C, 

 Upper molars. 1/3. (After Wortman.) 



with paraconid. 

 Torrejon beds. 



Lower Eocene ; 



Subfamily 2. Stylinodoxtinae. 

 '■ -7^„'- Skull and loicer jaw short. Articulation of the lower jaw 



much higher than the top of the teeth. C large, with very long root or with 

 persistent pulp. P^ and P^ placed transversely. Vertebrae with secondary 

 zygapophyses. 



Hemiganus Cope. 



2.1.4.3. 



Upper C entirely covered with enamel, but 



lower C only covered on the anterior surface. P and M with roots. Basal 

 Eocene; Puerco. 



