124 



UNGULATA 



ORDER VII 



lambda, etc., had no descendants. The dentition only of Didolodus (Fig. 155) 

 is comparatively well known. 



All members of this family are limited to the Eocene (Notostylops beds) 

 and the Oligocene (Astraponotus beds) of Patagonia. 



Fig. 155. 



Didolodus crassiauspis Ameghino. Notostylops strata of Upper 

 Eocene, Patagonia. A, Upper molars. B, Lower molars. C, Left 

 first upper molar, i/j. (After Ameghino.) 



Family 2. Macraucheniidae Gervais. 



Skxdl elongated, narrow, with small cranial region 

 and nostrils set far hack and upwardly directed. Nasals 



vestigial. „ ,' .'„ '• ^11 teeth in close 



small or 



3.1.4.3. 



series, and progressively changing from the simple anterior type to the complex 

 molars. Molars selenolophodont. Lower molars consisting of two semicrescental 

 ridges and one inner cusp. Upper molars tvith \N-shaped ectoloph, a large proto- 

 cone, which is united with the protoloph and metaloph, and a small hypocone. Manns 

 and pes tridactyl. Femur tvith third trochanter. A heel is well developed only on the 

 hinder side of the metapodials. 



The Macraucheniidae originate in the Eocene of Patagonia with bunodont- 

 brachyodont forms and become extinct in the Pleistocene of Argentina with 

 selenolophodont-hypsodont forms. They attain to a considerable size and 

 are distinguished by very high, digitigrade extremities, long neck and elongated 

 skull, with nostrils situated far back. The teeth are very like those of 

 Anoplotherium. Anterior and posterior edge of the inner side of the upper molars 

 and premolars form a high ridge. The 

 mode of life seems to have been aquatic. '-;"■ ^^'^j) 



Coniopternium, Protheosodon Ameghmo i ^^ j^'- 



Fio. 150. 



Protheosodon coniferus Ameghino. 

 therium strata of Lower Miocene, 

 molar, i/j. (After Ameghino.) 



Pyro- 

 Upper 



Fig. 157. 



Cramauchenia patagonica Ameghino. Middle 

 Miocene. Colpodon beds of Patagonia, a. Upper 

 Jl/2 ; b, upper P» ; c, lower il/o ; d, lower M3. Vi- 



(Fig. 156). Lower Miocene (Pyrotherium beds). Cramauchenia Ameghino 

 (Fig. 157) and Theosodon Ameghino. Miocene of Santa Cruz. All brachyo- 



