Sexual dimorphism in Equus

The main and commonly known sexual dimorphism in Equus is the presence of well developed canines at least on the maxillar in males and the almost constant lack of canines in females.

Moreover, the pubian symphysis is flatter in females after their first parturition.

Concerning the limb bones dimensions, the dimorphism is weak, too weak to discriminate male and female bones inside any sample. Even if the average dimensions are slightly larger in males, the largest dimension may well belong to a female (fig.3 in 142.Early Pleistocene equids (Mammalia, Perissodactyla) of Nalaikha (Mongolia) and the emergence of modern Equus. ).

The attached diagrams comparing males and females were done on an anterior limb bone (MC III) and a posterior one (talus) in a species where the male is territorial (E. grevyi) and another living in family groups (E. hemionus onager).

 

MC, E. grevyi males


 

MC, E. grevyi females


 

MC, E. grevyi males and females


 

Talus, E. grevyi males


 

Talus, E. grevyi females


 

Talus, E. grevyi males and females


 

MC, E. hemionus onager males


 

MC, E. hemionus onager females


 

MC, E. hemionus onager males and females


 

Talus, E. hemionus onager males


 

Talus, E. hemionus onager females