(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.
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 also 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.
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| Lagomorphs[1] Temporal range: Late Paleocene–Recent |
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|---|---|
| European Rabbit, Oryctolagus cuniculus, in Tasmania | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Infraclass: | Eutheria |
| Magnorder: | Boreoeutheria |
| Superorder: | Euarchontoglires |
| Order: | Lagomorpha Brandt, 1855 |
| Families | |
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Leporidae |
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| Range of Lagomorpha | |
The lagomorphs are the members of the taxonomic order Lagomorpha, of which there are two living families, the Leporidae (hares and rabbits), and the Ochotonidae (pikas). The name of the order is derived from the Greek lagos (λαγος, "hare") and morphē (μορφή, "form").
Though these mammals can resemble rodents (order Rodentia) and were classified as a superfamily in that order until the early twentieth century, they have since been considered a separate order. For a time it was common to consider the lagomorphs only distant relatives of the rodents, to whom they merely bore a superficial resemblance.
The evolutionary history of the lagomorphs is still not well understood. Until recently, it was generally agreed that Eurymylus, which lived in eastern Asia and dates back to the late Paleocene or early Eocene, was an ancestor of the lagomorphs.[2] More recent examination of the fossil evidence suggests that lagomorphs may have instead descended from mimotonids, while Eurymylus was more closely related to rodents (although not a direct ancestor.)[3] The leporids first appeared in the late Eocene and rapidly spread throughout the northern hemisphere; they show a trend towards increasingly long hind limbs as the modern leaping gait developed. The pikas appeared somewhat later in the Oligocene of eastern Asia.[4]
Lagomorphs differ from rodents in that:
However, they resemble rodents in that their teeth grow throughout their life, thus necessitating constant chewing to keep them from growing too long.
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