Rabbits aren’t rodents: four upper incisors give them away
Lagomorphs—order Lagomorpha—are the rabbits, hares (Leporidae), and pikas (Ochotonidae). About 109 living species in twelve genera span every continent but Antarctica. Closely related to rodents in Glires, they differ by sporting four upper incisors, fur-soled feet, and nearly pure herbivory.
The name joins Greek lagos (hare) and morphē (form); Johann Friedrich von Brandt coined Lagomorpha as a rodent suborder in 1855, and James W. Gidley elevated it to an order in 1912. Illiger’s 1811 Duplicidentata already flagged the double upper incisors. Fossils record far richer diversity—some seventy-five genera and over 230 species—than today’s fauna. Rose and colleagues (2008) favor an Indian Paleocene origin; earlier models pointed to Eurymylus or mimotonids. Leporids appear in the late Eocene; pikas in the Oligocene of eastern Asia.
All lagomorph teeth grow continuously, so fiber chewing is mandatory; cheek-tooth counts exceed rodents’. Females are typically larger than males; males lack an os penis and carry testes ahead of the penis. Rabbits and hares leap with powered hind limbs; pikas (~15 cm) keep equal legs, short noses, and mountain homes in western North America and Central Asia—rock specialists solitary, burrowers colonial and boom-bust. Hares (Lepus), 40–70 cm with ears to 20 cm, bear precocial young in above-ground forms; most rabbits (20–50 cm) bear altricial kits in burrows. Only the European rabbit is fully domesticated.
Digestion uses cecotrophy: fiber ferments in the cecum, then soft cecotropes are re-eaten for nutrients. Introduced European rabbits devastate parts of Australia; European hares occupy southern South America though native ranges exclude Antarctica, Madagascar, and many islands.
Large, frequent litters and rich milk let mothers feed briefly and forage—an underground-safety reproductive strategy.
Source: Lagomorpha
