24 



THE AGE OF MAMMALS 



LIMBS AND FEET 



VOLANT 



FOSSORIAL 



ARBOREAL 



Short-limbsd, plantigrad:^ 

 peiitadactyl, unguicu- 

 late Stem 



AMBULATORY 



or 

 TERRESTRL\L 



NATATORIAL 



Amphibious 



CURSORIAL 

 Digit igrade 



Aquatic 



Unguligrade 



fFish 

 CARNIVOROUS j Fish 

 I Carrion 



TEETH 



OMNIVOROUS 



HERBIVOROUS 



■ Grass 

 Herb 

 Shrub 

 Fruit 

 Root 



MYRMECOPHAGOUS 



Dentition reduced 



Stem INSECTIVOROUS 



forms. Similarly, Matthew ^ has suggested that most placental mammals 

 bear evidence of descent from primitive arboreal ancestors. 



Similarly, in the case of the teeth, insectivorous and omnivorous types 

 appear to be more central and ancient than either the exclusively carnivo- 

 rous or herbivorous types. Thus the extremes of carnivorous adaptation, 

 as in the case of the cats, of omnivorous adaptation, as in the case of the 

 bears, of herbivorous adaptation, as in the case of the horses, or myrme- 

 cophagous adaptation, as in the case of the anteaters, are all secondary. 



^ Matthew, W. D., The Arboreal Ancestry of the Mammalia. 

 Vol. XXXVIII, nos. 445-446, Nov.-Dec, 1904. 



Amer. Natural., 



