Lagomorpha

Lagomorphs
Temporal range: Late Paleocene – recent
Eastern cottontail (Sylvilagus floridanus)
Large-eared pika (Ochotona macrotis)
Scientific classification Edit this classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Grandorder: Glires
Mirorder: Duplicidentata
Order: Lagomorpha
Brandt, 1855
Families
Range of Lagomorpha including areas of human introduction
Fossil occurrences of leporids and ochotonids and global environmental change (climate change, C3/C4 plants distribution)

The lagomorphs (/ˈlæɡəˌmɔːrf/; from Ancient Greek λαγώς lagós 'hare' and μορφή morphḗ 'form') are the members of the taxonomic order Lagomorpha, of which there are two living families: the Leporidae (rabbits and hares) and the Ochotonidae (pikas). There are 110 recent species of lagomorph, of which 109 species in twelve genera are extant, including ten genera of rabbits (42 species), one genus of hare (33 species), and one genus of pika (34 species); and in which one monospecific genus is recently extinct, that of the Sardinian pika. Lagomorphs are found on every continent in the world except Antarctica, with several regions being host to introduced populations of European rabbits and European hares.

Lagomorphs are closely related to rodents. The two groups are differentiated by their teeth: rodents have two upper incisors, while lagomorphs have four. However, both lagomorphs and rodents must chew on foods with plenty of fiber to prevent these incisors from getting too long, as they will grow continuously throughout these animals' lifespan. Lagomorphs have more cheek teeth (molars and premolars) than do rodents, and they are almost exclusively herbivores. Lagomorphs do not have paw pads – the undersides of their feet are covered in fur.

The term "lagomorph" was first used in the 19th century, and combines the Ancient Greek words for "hare" and "form" to describe an animal that is "hare shaped". The order Lagomorpha was originally a suborder, placed alongside other groups of rodents, and was clarified as being a unique order in 1912. Rabbits, hares and pikas were first grouped together under the name Duplicidentata in 1811 based on the shared characteristic of four upper incisors. The order's evolutionary history is not well understood, though fossil records indicate many more species lived in the past than are currently living – at least twice as many.

Etymology

The name "lagomorph" is derived from two Ancient Greek terms: lagos (λαγώς) 'hare' and morphē (μορφή) 'form'. Together, they describe an animal that is "hare shaped". The title is first attested to in the 19th century. It was coined by the German naturalist Johann Friedrich von Brandt in 1855, who called for a reorganization of the subdivision of rodents containing the rabbits, hares, and pikas. At the time, he described "Lagomorpha" as a suborder of the rodents, which also included Sciuromorpha, Myomorpha, and Hystricomorpha. Lagomorpha was not formally described as an order until American palaeontologist James W. Gidley described it as such in 1912.

Taxonomy and evolutionary history

Other names used for this order, now considered synonymous, include Duplicidentata (Illiger, 1811), Leporini and Leporinorum (Fischer, 1917), Leporida (Averianov, 1999), Neolagomorpha (Averianov, 1999), Ochotonida (Averianov, 1999), and Palarodentia (Haeckel, 1895; Lilian, 2016). The lagomorphs were first described as a group distinct from the rest of the rodents, as they were first classified, in 1811 by Johann Karl Wilhelm Illiger when he erected Duplicidentata. At the time, the rabbit, pikas, and hares were contained in only two genera, Lepus and Lagomys (the hares and the pikas), and it was seen as necessary to further distinguish these animals from rodents based on their teeth, specifically the lagomorphs' four upper incisors. Naturalists would apply various names to this grouping through the following decades, with one of these names being Leporidae, which would later be used to describe just the hares and rabbits. Johann Friedrich von Brandt created the name Lagomorpha in 1855, and this name was solidified as an order in 1912.

The evolutionary history of the lagomorphs is still not well understood. In the late 20th century, 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. More recent 21st-century fossil evidence suggests that the lagomorphs may have instead descended from mimotonids, mammals from Paleogene Asia with similar body size and dental structure to early European rabbits such as Megalagus turgidus. Eurymylus is now considered more closely related to rodents (although not a direct ancestor). The name Duplicidentata is sometimes revived to refer to the total group of lagomorphs (i.e., all mammals more closely related to lagomorphs than to rodents). Mimotonids are an example of non-lagomorph duplicidentates.

A 2008 study by evolutionary biologist Kenneth D. Rose and colleagues suggests an Indian origin for the lagomorph order, having possibly evolved in isolation when India was an island continent in the Paleocene. Lagomorph fossils appeared in East Asia in the early Eocene, reaching North America in the late Eocene and Europe in the early Oligocene. Pikas and leporids are estimated to have diverged by the mid-Eocene. The oldest pika is likely Desmatolagus, a small but widespread mammal which lasted from the late Eocene into the early Miocene. Despite the extinction of Desmatolagus, pikas as a whole reached their maximum diversity in the early-middle Miocene, thriving across Asia, Europe, North America, and Africa.

Litolagus, from early Oligocene North America, may be the oldest leporid, and it was certainly one of the earliest to acquire the high-crowned teeth distinctive to modern rabbits and hares. Leporid diversity was relatively low for the next 25 million years, but in the late Miocene (circa 8 million years ago) they abruptly diversified and spread throughout the Northern Hemisphere, in an event called the Leporid Datum. By 7 million years ago, they expanded further into South America and Africa. Leporids show a trend towards increasingly long hind limbs as the modern leaping gait developed.

Lagomorphs were certainly more diverse in the past than in the present, with around 75 genera and over 230 species represented in the fossil record and many more species in a single biome. Lagomorph lineages are declining.

Characteristics

Lagomorphs are similar to other mammals in that they all have hair, four limbs (i.e., they are tetrapods), and mammary glands and are endotherms. Lagomorphs possess a moderately fused postorbital process to the cranium, unlike other small mammals. They differ in that they have a mixture of "basal" and "derived" physical traits.

Differences between lagomorphs and other mammals

Lagomorphs and rodents form the clade or grandorder Glires. Despite the evolutionary relationship between lagomorphs and rodents, the two orders have some major differences.

Lagomorphs have four incisors in the upper jaw (smaller peg teeth behind larger incisors), whereas rodents only have two. They are similar to rodents in that their incisors grow continuously, thus necessitating constant chewing on fibrous food to prevent the teeth from growing too long. In addition, all lagomorph teeth grow continuously, while for most rodents, only the incisors grow continuously. Lagomorph and rodent incisors are structured differently. Lagomorphs have more cheek teeth than rodents. Both have a large diastema.

Lagomorphs are almost strictly herbivorous, unlike rodents, many of which will eat both meat and vegetable matter. Lagomorphs have no paw pads; instead, the bottoms of their paws are entirely covered with fur, a trait they share with red pandas. Similar to the rodents, bats, and some mammalian insectivores, they have a smooth-surfaced cerebrum. Lagomorphs are unusual among terrestrial mammals in that the females are larger than males and that the testes of males are usually located in front of the penis. Male lagomorphs do not have an os penis. Females have two to five pairs of mammary glands.

Differences between families of lagomorphs

Rabbits and hares move by jumping, pushing off with their strong hind legs and using their forelimbs to soften the impact on landing. Pikas lack certain skeletal modifications present in leporids, such as a highly arched skull, an upright posture of the head, strong hind limbs and pelvic girdle, and long limbs. Also, pikas have a short nasal region and entirely lack a supraorbital foramen, while leporids have prominent supraorbital foramina and nasal regions.

Pikas

American pika in Alberta

Pikas are entirely represented by the family Ochotonidae and are small mammals native to mountainous regions of western North America and Central Asia. They are mostly about 15 cm (6 in) long and have greyish-brown, silky fur, small rounded ears, and almost no tail. Their four legs are nearly equal in length. Some species live in scree, making their homes in the crevices between broken rocks, while others construct burrows in upland areas. The rock-dwelling species are typically long-lived and solitary, having one or two small litters each year contributing to stable populations. The burrowing species, in contrast, are short-lived, gregarious and have multiple large litters during the year. These species tend to have large swings in population size. The gestation period of the pika is around one month long, and the newborns are altricial (eyes and ears closed, no fur). The social behaviour of the two groups also differs: the rock dwellers aggressively maintain scent-marked territories, while the burrowers live in family groups, they interact vocally with each other and defend a mutual territory. Pikas are diurnal and are active early and late in the day during hot weather. They feed on all sorts of plant material. As they do not hibernate, they make "haypiles" of dried vegetation which they collect and carry back to their homes to store for use during winter.

Hares

Scrub hare in South Africa

Hares, members of genus Lepus of family Leporidae, are medium size mammals native to Europe, Asia, Africa, and North America. North American jackrabbits are actually hares. Species vary in size from 40 to 70 cm (16 to 28 in) in length and have long powerful back legs, and ears up to 20 cm (8 in) in length. Although usually greyish-brown, some species turn white in the winter. They are solitary animals. Newborns are precocial (eyes and ears open, fully furred). Several litters are born during the year in a form (a nest above ground, usually under a bush). They are preyed upon by large mammalian carnivores and birds of prey.

Rabbits

Rabbits, members of the Leporidae family (excluding Lepus (hares)) are generally much smaller than hares and include the rock hares and the hispid hare. They are native to Europe, parts of Africa, Central and Southern Asia, North America and much of South America. They inhabit both grassland and arid regions. They vary in size from 20 to 50 cm (8 to 20 in) and have long, powerful hind legs, shorter forelegs and a tiny tail. The colour is some shade of brown, buff or grey and there is one black species and two striped ones. Domestic rabbits come in a wider variety of colours. Newborn rabbits are altricial (eyes and ears closed, no fur). Although most species live in burrows, the cottontails and hispid hares have forms (nests above ground, usually under a bush). Most of the burrowing species are colonial, and feed together in small groups. Rabbits play an important part in the terrestrial food chain, eating a wide range of forbs, grasses, and herbs, and being part of the staple diet of many carnivorous species. One species of rabbit has been domesticated, that being the European rabbit.

Distribution

Lagomorphs are widespread around the world and inhabit every continent except Antarctica. However, they are not found in the West Indies or Madagascar, nor on many islands. Although they are not native to Australia, European rabbits have been introduced there, where they have successfully colonized many parts of the country and caused disruption to native species. Though they are not native there, European hares exist in much of the southern cone of South America.

Biology

Digestion

Skeleton of Alaskan hare (Museum of Osteology)

Easily digestible food is processed in the gastrointestinal tract and expelled as regular feces. But in order to get nutrients out of hard to digest fiber, lagomorphs ferment fiber in the cecum (in the GI tract) and then expel the contents as cecotropes, which are reingested (cecotrophy). The cecotropes are then absorbed in the small intestine to utilize the nutrients. Like rodents, they are not able to vomit.

Birth and early life

Many lagomorphs breed several times a year and produce large litters. This is particularly the case in species that live in underground, protective environments, such as burrows. The young of rabbits and pikas (called kits) are born after a short gestation period and the mother can become pregnant again almost immediately after giving birth. The mothers are able to leave these young safely and go off to feed, returning at intervals to feed them with their unusually rich milk. In some species, the mother only visits and feeds the litter once a day but the young grow rapidly and are usually weaned within a month.

Sociality and safety

Many species of lagomorphs, particularly the rabbits and the pikas, are gregarious and live in colonies, whereas hares are generally solitary species, although many hares travel and forage in groups of two, three, or four. Many rabbits and pikas rely on their burrows as places of safety when danger threatens, but hares rely on their long legs, great speed and jinking gait to escape from predators.

Classification

Alloptox japonicus jaw
Palaeolagus skull

Recent genera

Fossil genera

References

  1. ↑ Ge, Deyan; Wen, Zhixin; Xia, Lin; Zhang, Zhaoqun; Erbajeva, Margarita; Huang, Chengming; Yang, Qisen (April 3, 2013). "Evolutionary History of Lagomorphs in Response to Global Environmental Change". PLoS ONE. 8 (4:e59668) e59668. Bibcode:2013PLoSO...859668G. doi:10.1371/journal.pone.0059668. PMC 3616043. PMID 23573205.
  2. ↑ "Definition of Lagomorph". Merriam-Webster.com Dictionary. Merriam-Webster. Archived from the original on 2025-09-20. Retrieved 2025-07-17.
  3. ↑ Feldhamer, George A.; Merritt, Joseph F.; Krajewski, Carey; Rachlow, Janet L.; Stewart, Kelley M. (2020). Mammalogy: adaptation, diversity, ecology (5th ed.). Baltimore: Johns Hopkins University Press. p. 359. ISBN 978-1-4214-3652-4. LCCN 2019017733.
  4. ↑ "Lagomorph". Oxford English Dictionary (online ed.). Oxford University Press. doi:10.1093/OED/1143256094. Retrieved 17 July 2025. (Subscription or participating institution membership required.)
  5. 1 2 Ruedas, Luis A.; Mora, José M.; Lanier, Hayley C. (2018). "Evolution of Lagomorphs". In Smith, Andrew T.; Johnston, Charlotte H.; Alves, Paulo C.; Hackländer, Klaus (eds.). Lagomorphs: Pikas, Rabbits, and Hares of the World. Johns Hopkins University Press. doi:10.1353/book.57193. ISBN 978-1-4214-2341-8. LCCN 2017004268.
  6. 1 2 3 Hoffmann, R.S.; Smith, A.T. (2005). "Order Lagomorpha". In Wilson, D.E.; Reeder, D.M (eds.). Mammal Species of the World: A Taxonomic and Geographic Reference (3rd ed.). Johns Hopkins University Press. pp. 185–211. ISBN 978-0-8018-8221-0. OCLC 62265494.
  7. ↑ Savage, RJG (1986). Mammal Evolution: an illustrated guide. Illustrated by Long, MR. New York: Facts on File. pp. 128–129. ISBN 0-8160-1194-X.
  8. ↑ Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 285. ISBN 1-84028-152-9.
  9. ↑ Fostowicz-Frelik, Łucja; Li, Chuankui; Mao, Fangyuan; Meng, Jin; Wang, Yuanqing (2015-03-30). "A large mimotonid from the Middle Eocene of China sheds light on the evolution of lagomorphs and their kin". Scientific Reports. 5 (1): 9394. Bibcode:2015NatSR...5.9394F. doi:10.1038/srep09394. ISSN 2045-2322. PMC 4377629. PMID 25818513.
  10. ↑ Fostowicz-Frelik, Łucja (2020), Pontarotti, Pierre (ed.), "Most Successful Mammals in the Making: A Review of the Paleocene Glires", Evolutionary Biology—A Transdisciplinary Approach, Cham: Springer International Publishing, pp. 99–116, doi:10.1007/978-3-030-57246-4_5, ISBN 978-3-030-57245-7, retrieved 2026-10-13{{citation}}: CS1 maint: work parameter with ISBN (link)
  11. 1 2 3 Kraatz, Brian; Belabbas, Rafik; Fostowicz-Frelik, Łucja; Ge, De-Yan; Kuznetsov, Alexander N.; Lang, Madlen M.; López-Torres, Sergi; Mohammadi, Zeinolabedin; Racicot, Rachel A.; Ravosa, Matthew J.; Sharp, Alana C.; Sherratt, Emma; Silcox, Mary T.; Słowiak, Justyna; Winkler, Alisa J. (2021-07-01). "Lagomorpha as a Model Morphological System". Frontiers in Ecology and Evolution. 9 636402. Bibcode:2021FrEEv..0936402K. doi:10.3389/fevo.2021.636402. hdl:2440/131722. ISSN 2296-701X.
  12. 1 2 3 4 Zhang, Zhao-Qun; Wang, Bian (2025). "The origin and evolutionary history of Lagomorpha (Mammalia) in China". Journal of Mammalian Evolution. 32 (4) 49. doi:10.1007/s10914-025-09794-z. ISSN 1064-7554.
  13. ↑ Rose, Kenneth David (2006). The Beginning of the Age of Mammals. The Johns Hopkins University Press. p. 315. ISBN 0-8018-8472-1.
  14. ↑ Rose, K.D.; Deleon, V.B.; Mmissian, P.; Rana, R.S.; Sahni, A.; Singh, L.; Smith, T. (2008). "Early Eocene lagomorph (Mammalia) from western India and the early diversification of Lagomorpha". Proceedings of the Royal Society B. 275 (1639): 1203–1208. Bibcode:2008PBioS.275.1203R. doi:10.1098/rspb.2007.1661. PMC 2602686. PMID 18285282.
  15. ↑ Lopez-Martinez, Nieves (2008). "The Lagomorph Fossil Record and the Origin of the European Rabbit". In Alves, Paulo C.; Ferrand, Nuno; Hackländer, Klaus (eds.). Lagomorph Biology: Evolution, Ecology, and Conservation. Berlin, Heidelberg: Springer. pp. 27–46. doi:10.1007/978-3-540-72446-9. ISBN 978-3-540-72445-2. OCLC 166358165. [...] which denotes that lagomorph lineages are also declining in recent times.
  16. ↑ Wible, John R. (January 2007). "On the Cranial Osteology of the Lagomorpha". Bulletin of Carnegie Museum of Natural History. 2007 (39): 213–234. doi:10.2992/0145-9058(2007)39[213:OTCOOT]2.0.CO;2. ISSN 0145-9058. S2CID 85766674.
  17. ↑ Best, T. L.; Henry, T. H. (1994-06-02). "Lepus arcticus". Mammalian Species (457): 1–9. doi:10.2307/3504088. ISSN 0076-3519. JSTOR 3504088. S2CID 253989268.
  18. 1 2 Smith, Andrew T. "Lagomorph". Encyclopædia Britannica. Archived from the original on 2018-01-20. Retrieved 2020-09-08.
  19. ↑ Myers, Phil. "Lagomorpha; hares, pikas, and rabbits". Animal Diversity (ADW). Archived from the original on 2024-01-10. Retrieved 2024-01-03.
  20. ↑ "Structure and placement of individual teeth". Animal Diversity (ADW). Retrieved 2024-01-03.
  21. ↑ Böhmer, Estella (2015-02-17). "Classification and Anatomical Characteristics of the Lagomorphs and Rodents". Dentistry in Rabbits and Rodents (1st ed.). Wiley. pp. 21–34. doi:10.1002/9781118802557.ch3. ISBN 978-1-118-80254-0. Archived from the original on 2024-01-27. Retrieved 2026-07-15.
  22. ↑ "Pika; mammal". Encyclopedia Britannica. Archived from the original on 2021-08-26. Retrieved 2021-06-26.
  23. ↑ Macdonald, David W. (David Whyte) (1984). The Encyclopedia of mammals. Internet Archive. New York, NY : Facts on File. ISBN 978-0-87196-871-5.
  24. ↑ Fisher, Rebecca E. (2021). "Red Panda Anatomy". In Glatston, Angela R. (ed.). Red Panda: Biology and Conservation of the First Panda (2nd ed.). London: Academic Press. pp. 81–93. doi:10.1016/B978-0-12-823753-3.00030-2. ISBN 978-0-12-823753-3. S2CID 243824295.
  25. ↑ Ferrer, I.; Fabregues, I.; Condom, E. (1986). "A Golgi study of the sixth layer of the cerebral cortex I: The lissencephalic brain of Rodentia, Lagomorpha, Chiroptera, and Insectivora". Journal of Anatomy. 145 pdf/janat00188-0215.pdf: 217–234. PMC 1166506. PMID 3429306.[need quotation to verify]
  26. ↑ Ralls, Katherine (June 1976). "Mammals in Which Females are Larger Than Males". The Quarterly Review of Biology. 51 (2): 245–276. doi:10.1086/409310. PMID 785524. S2CID 25927323.
  27. ↑ Miller, R. Eric; Fowler, Murray E. (2014-06-02). Fowler's Zoo and Wild Animal Medicine, Volume 8. Elsevier Health Sciences. ISBN 978-1-4557-7399-2.
  28. 1 2 Smith, Andrew T. "Pika". Encyclopædia Britannica. Archived from the original on 2020-11-12. Retrieved 2020-09-08.
  29. ↑ "IUCN - Lagomorph specialist group". www.iucn.org. Archived from the original on 2015-08-03. Retrieved 2015-08-18.
  30. ↑ "American Pika". National Wildlife Federation. Archived from the original on 2018-11-19. Retrieved 2018-11-19.
  31. ↑ Smith, Andrew T. "Hare". Encyclopædia Britannica. Archived from the original on 2020-08-03. Retrieved 2020-09-08.
  32. ↑ Klappenbach, Laura. "Hares, Rabbits and Pikas". About.com Education. About.com. Archived from the original on 2013-10-20. Retrieved 2013-08-14.
  33. ↑ Hacklander, K.; Schai-Braun, S. (2019). "Lepus europaeus". IUCN Red List of Threatened Species. 2019 e.T41280A45187424. doi:10.2305/IUCN.UK.2019-1.RLTS.T41280A45187424.en. Retrieved 29 October 2025.
  34. ↑ "Exploring a Rabbit's Unique Digestive System". Rabbits for Dummies. Archived from the original on 2013-08-09. Retrieved 2013-08-14.
  35. ↑ Horn, C. C.; Kimball, B. A.; Wang, H.; Kaus, J.; Dienel, S.; Nagy, A.; Gathright, G. R.; Yates, B. J.; Andrews, P. L. (2013). "Why Can't Rodents Vomit? A Comparative Behavioral, Anatomical, and Physiological Study". PLOS ONE. 8 (4) e60537. Bibcode:2013PLoSO...860537H. doi:10.1371/journal.pone.0060537. PMC 3622671. PMID 23593236.
  36. 1 2 "Lagomorpha". Fossilworks. Gateway to the Paleobiology Database. Retrieved 13 May 2010.