Leporidae

Rabbits and hares[1]
Temporal range: 53–0Ma

Late, possibly early Eocene – Recent

Arctic hare (Lepus arcticus)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Lagomorpha
Family: Leporidae
Fischer de Waldheim, 1817
Genera

Pentalagus
Bunolagus
Nesolagus
Romerolagus
Brachylagus
Sylvilagus
Oryctolagus
Poelagus
Caprolagus
Pronolagus
Lepus

The Leporidae are a family of mammals that include rabbits and hares, over 60 species in all. The Latin word Leporidae means "those that resemble lepus" (hare). Together with the pikas, the Leporidae constitute the mammalian order Lagomorpha. Leporidae differ from pikas in that they have short, furry tails and elongated ears and hind legs.

The term "leporid" may be used as a noun ("a member of the family Leporidae") or as an adjective ("like members of the Leporidae"). The common name "rabbit" usually applies to all genera in the family except Lepus, while members of Lepus (almost half the species) usually are called hares. Like most common names however, the distinction does not match current taxonomy completely; jackrabbits are members of Lepus, and members of the genera Pronolagus and Caprolagus sometimes are called hares.

Various countries across all continents except Antarctica and Australia have indigenous species of Leporidae. Furthermore rabbits, most significantly the European rabbit, Oryctolagus cuniculus, also have been introduced to most of Oceania and to many other islands, where they pose serious ecological and commercial threats.

Characteristics

Leporids are small to moderately sized mammals, adapted for rapid movement. They have long hind legs, with four toes on each foot, and shorter fore legs, with five toes each. The soles of their feet are hairy, to improve grip while running, and they have strong claws on all of their toes. Leporids also have distinctive, elongated and mobile ears, and they have an excellent sense of hearing. Their eyes are large, and their night vision is good, reflecting their primarily nocturnal or crepuscular mode of living.[2]

Leporids range in size from the pygmy rabbit (Brachylagus idahoensis), with a head and body length of 25–29 cm, and a weight of around 300 grams, to the European hare (Lepus europaeus), which is 50–76 cm in head-body length, and weighs from 2.5 to 5 kilograms.

Both rabbits and hares are almost exclusively herbivorous (with exceptions among the members of Lepus),[3][4] feeding primarily on grasses and herbs, although they also eat leaves, fruit, and seeds of various kinds. They are coprophagous, as they pass food through their digestive systems twice, first expelling it as soft green feces, called cecotropes, which they then reingest, eventually producing hard, dark fecal pellets. Like rodents, they have powerful front incisor teeth, but they also have a smaller second pair of incisors to either side of the main teeth in the upper jaw, and the structure is different from that of rodent incisors. Also like rodents, leporids lack any canine teeth, but they do have more cheek teeth than rodents do. Their jaws also contain a large diastema. The dental formula of most, though not all, leporids is: 2.0.3.31.0.2.3

They have adapted to a remarkable range of habitats, from desert to tundra, forests, mountains, and swampland. Rabbits generally dig permanent burrows for shelter, the exact form of which varies between species. In contrast, hares rarely dig shelters of any kind, and their bodies are more suited to fast running than to burrowing.[2]

The gestation period in leporids varies from around 28 to 50 days, and is generally longer in the hares. This is in part because young hares, or leverets, are born fully developed, with fur and open eyes, while rabbit kits are naked and blind at birth, having the security of the burrow to protect them.[2] Leporids can have several litters a year, which can cause their population to expand dramatically in a short period of time when resources are plentiful.

Evolution

Serengetilagus praecapensis skull, Naturkundemuseum, Berlin

The oldest known leporid species date from the late Eocene, by which time the family was already present in both North America and Asia. Over the course of their evolution, this group has become increasingly adapted to lives of fast running and leaping. For example, Palaeolagus, an extinct rabbit from the Oligocene of North America, had shorter hind legs than modern forms (indicating it ran rather than hopped) though it was in most other respects quite rabbit-like.[5] Two as yet unnamed fossil finds—dated ~48 Ma (from China) and ~53 Ma (India)—while primitive, display the characteristic leporid ankle, thus pushing the divergence of Ochotonidae and Leporidae yet further into the past.[6] The genus Praotherium was once considered to be part of this family,[7] but this is now in doubt.[8]

Classification

Family Leporidae:[1] rabbits and hares

See also

References

  1. ↑ 1.0 1.1 Hoffman, R. S.; Smith, A. T. (2005). "Order Lagomorpha". In Wilson, D. E.; Reeder, D. M. Mammal Species of the World (3rd ed.). Johns Hopkins University Press. pp. 194–211. ISBN 978-0-8018-8221-0. OCLC 62265494.
  2. ↑ 2.0 2.1 2.2 Chapman, J. & Schneider, E. (1984). MacDonald, D., ed. The Encyclopedia of Mammals. New York: Facts on File. pp. 714–719. ISBN 0-87196-871-1.
  3. ↑ Best, Troy L.; Henry, Travis Hill (1994). "Lepus arcticus". Mammalian Species (American Society of Mammalogists, published June 2, 1994) (457): 1–9. doi:10.2307/3504088. JSTOR 3504088. OCLC 46381503.
  4. ↑ "Snowshoe Hare". eNature: FieldGuides. eNature.com. 2007. Retrieved 2008-03-23.
  5. ↑ Savage, RJG, & Long, MR (1986). Mammal Evolution: an illustrated guide. New York: Facts on File. pp. 128–129. ISBN 0-8160-1194-X.
  6. ↑ Handwerk, Brian (2008-03-21). "Easter Surprise: World's Oldest Rabbit Bones Found". National Geographic News (National Geographic Society). Retrieved 2008-03-23.
  7. ↑ "Leporidæ", Century Dictionary and Cyclopedia
  8. ↑ "Praotherium palatinum (nomen dubium)". The Paleobiology Database. Retrieved 16 January 2013.
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