to 



University of California Publications. 



f Geology 



rather large form with short facial region and heavy-bladed car- 

 nassials, it was probably a rapidly specializing form. The trend 

 of its specialization seems to have been toward the Aelurodon 

 type. 



Aelurodon, was represented by several species in the Loup 

 Fork epoch, but I am not aware of the existence of any remains 

 from older beds. The Mascall beds have been thought to repre- 

 sent a somewhat earlier epoch than the typical Loup Fork, and 

 it is at precisely this horizon that we would search for the ances- 

 tral type of the Aelurodon group. While it is not necessarily 

 true that Teprhocyon rurestris is directly ancestral to Aelurodon, 

 it seems to represent a tendency toward specialization in that 

 direction in the Canidae, at the time when the genus Aelurodon 

 probably had its origin, and it is evidently not far removed from 



this line of descent. 



MEASUREMENTS. 



mm. 



Length, anterior end of orbit to inion 124 



Length, postorbital process to inion 97 



Width between orbits 38 



Width across snout above middle of superior canine 38 



Length of mandible from anterior side of P t to posterior 



side of condyle 108 



Height of mandible below protocone of M t 20 



Length, anterior side of P 1 to posterior side of M 2 60 



Length, anterior side of P, to posterior side of M 3 66 



Antero-posterior diameter of superior canine at base 10 



P 2 , antero-posterior diameter 8.5 



P 3 , antero-posterior diameter 10 



P 4 , antero-posterior diameter 17 



P 4 , greatest transverse diameter 9.5 



M 1 , antero-posterior diameter 13 



M l , greatest transverse diameter 16 



M 1 , antero-posterior diameter across protocone 10 



M 2 , antero-posterior diameter 7.7 



M 2 , greatest transverse diameter 12 



P 2 , antero-posterior diameter 7.5 



P 3 , antero-posterior diameter 9 



P 4 , antero-posterior diameter 11.5 



M 1; antero-posterior diameter 20 



M x , antero-posterior diameter of heel 6 



M 2 , antero-posterior diameter 11.5 



M 2 , antero-posterior diameter of heel 4 



M 3 , antero-posterior diameter 5 



