How does paraxonic limb support help distinguish artiodactyls from perissodactyls?

The distinction between artiodactyls and perissodactyls is defined by the primary weight-bearing axis of their limbs, a fundamental anatomical difference in mammalian evolution.12

• Artiodactyls (Paraxonic): In these mammals, the main weight-bearing axis of the leg passes between the third and fourth toes. This paraxonic support is characterized by the development of these two central toes, while the second and fifth toes flanking them have progressively declined.12
• Perissodactyls (Mesaxonic): In contrast, these herbivores utilize mesaxonic limb support, where the weight-bearing axis passes through the third or central toe alone. This digit is the most strongly developed, and in highly specialized forms like the horse, it serves as the primary point of contact with the ground, while other digits are reduced or vestigial.12

This structural divergence reflects different evolutionary paths toward efficient locomotion, with artiodactyls balancing weight across two digits and perissodactyls concentrating it on a single central axis.12