The 21 Basic Mammal Groups
Odd-Toed Hoofed Mammals (Order Perissodactyla)
Compared to their even-toed artiodactyl cousins, odd-toed perissodactyls are a sparse lot, consisting entirely of horses, zebras, rhinoceroses, and tapirs — only about 20 species in all. Besides the unique structure of their feet, perissodactyls are characterized by a pouch called a "caecum" that extends from their large intestines. It contains specialized bacteria that aids in the digestion of tough plant matter. According to molecular analysis, odd-toed mammals may be more closely related to carnivores (order Carnivora) than they are to even-toed mammals (order Artiodactyla).
The 21 Basic Mammal Group caches were placed for HNY21.