Lagomorpha

Lagomorpha [‚lag·ə′mȯr·fə]

(vertebrate zoology)

The order of mammals including rabbits, hares, and pikas; differentiated from rodents by two pairs of upper incisors covered by enamel, vertical or transverse jaw motion, three upper and two lower premolars, fused tibia and fibula, and a spiral valve in the cecum.

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Lagomorpha

The order of mammals including rabbits, hares, and pikas. Lagomorphs have two pairs of upper incisors (the second pair minute), and enamel surrounds the tooth, which does not form a sharp chisel. Motion of the jaw is vertical or transverse. Lagomorphs have three upper and two lower premolars, the earliest fossil rodents have one less of each. The tibia and fibula are fused, the fibula articulating with the calcaneum as in artiodactyls. There is a spiral valve in the cecum, and the scrotum is prepenial.

The order includes three families: Leporidae (rabbits and hares); Ochotonidae (pikas, whistling hares, or American coneys); and Eurymylidae, an extinct family from the Paleocene of Mongolia. See Mammalia

Leporidae are the most familiar members of the order. There are, in general, two kinds: rabbits (such as the American cottontail), which are relatively small, with shorter hindlegs, shorter ears, and short tails; and hares, larger forms with longer legs, ears, and tails. Rapid locomotion is by leaps, using the hindlegs, combined (especially in rabbits) with abrupt changes of direction. Both types occur in the same region, with rabbits inhabiting brush, scrub, or woods and hares living in open grassland. In North America, hares are usually called jackrabbits.