44 THE DESEADO FORMATION OF PATAGONIA 



MEASUREMENTS 



Lower dentition, total length 114 mm. 



incisors, length 20 mm. 



canine, length 8 mm. 



premolar 2 to 4 35 mm. 



molar I to 3 42 mm. 



Mandible, total length 188 mm. 



height under molar I 24 mm. 



height to top of coronoid 95 mm. 



The dorsal vertebrae have short, wide, and somewhat 

 depressed centra (in this individual the epiphyses are 

 free, though this is the only indication of youth). The 

 lower rib facets are small, that on the posterior margin of 

 the centrum being a mere streak, while the one on the 

 anterior margin is narrow. The upper rib facet is a rounded 

 convex surface on the end of a short stout transverse proc- 

 ess. The prezygapophyses are convex surfaces, wide 

 transversely, but narrow in the anteroposterior direction, 

 while the postzygapophyses are correspondingly narrow 

 concave facets under the rear of the spines. The spines 

 are thin and high, and the neural canal is nearly circular in 

 section. 



The lumbar vertebrae have laterally compressed, deep 

 centra, with very long transverse processes, shorting spines, 

 and zygapophyses of the subcylindrical interlocking type. 

 In all their features the vertebrae resemble those of Theo- 

 sodon, being nearly as highly specialized and in the same 

 manner. 



MEASUREMENTS OF TYPICAL VERTEBRAE 



Dorsal vertebra No. 7, length 23 mm. 



width of centrum 22 mm. 



Dorsal vertebra No. 9, length 28 mm. 



Lumbar vertebra No. 2, length 29 mm. 



Lumbar vertebra No. 2, width of centrum 24 mm. 



Lumbar vertebra No. 2, width across transverse processes 160 mm. 



The femur is short and very stocky. The rounded head 

 is carried on a short neck, and does not rise nearly as high 

 as the greater trochanter, the sulcus for the round liga- 



