Lagomorpha

The lagomorphs (; 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...