Editing Perissodactyla (section)

==Research history==
[[File:Richard Owen 1856.jpg|thumb|right|Richard Owen, 1856]]
In 1758, in his seminal work ''Systema Naturae'', [[Carl Linnaeus|Linnaeus]] (1707–1778) classified horses (''Equus'') together with [[hippo]]s (''Hippopotamus''). At that time, this category also included the tapirs (''Tapirus''), more precisely the lowland or South American tapir (''Tapirus terrestus''), the only tapir then known in Europe. Linnaeus classified this tapir as ''Hippopotamus terrestris'' and put both genera in the group of the ''Belluae'' ("beasts"). He combined the rhinos with the [[Glires]], a group now consisting of the [[Lagomorpha|lagomorphs]] and [[rodent]]s. [[Mathurin Jacques Brisson]] (1723–1806) first separated the tapirs and hippos in 1762 with the introduction of the concept ''le tapir''. He also separated the rhinos from the rodents, but did not combine the three families now known as the odd-toed ungulates. In the transition to the 19th century, the individual perissodactyl genera were associated with various other groups, such as the [[proboscidea]]n and [[even-toed ungulate]]s. In 1795, Étienne Geoffroy Saint-Hilaire (1772–1844) and [[Georges Cuvier]] (1769–1832) introduced the term "pachyderm" ([[Pachydermata]]), including in it not only the rhinos and elephants, but also the hippos, pigs, [[peccary|peccari]]es, tapirs and hyrax.<ref name="Simpson 1945"/><ref name="Schoch 1989"/><ref>{{cite journal|author1=Étienne Geoffroy Saint-Hilaire|author2=Georges Cuvier|title=Memoire sur une nouvelle division of Mammifères, et sur les principes qui doivent servir de base dans cette sorte de travail|journal=Magasin Encyclopédique|year=1795|pages=164–190}}</ref><ref>{{cite journal|author=Georges Cuvier|title=Le Règne Animal distribue d'après son organisation pour servir de base à l'histoire naturelle des animaux|journal=Introduction à l'Anatomie Comparée|volume=1|year=1817|pages=1–540}}</ref> The horses were still generally regarded as a group separate from other mammals and were often classified under the name ''Solidungula'' or ''Solipèdes'', meaning "one-hoof animal".<ref>{{cite book|author=Johann Friedrich Blumenbach|title=Handbook of Natural History|year=1779|pages=168–448}}</ref><ref>{{cite journal|author=Georges Cuvier|title=Tableau Elementaire de l'histoire naturelle des animaux|year=1798|url=https://archive.org/stream/tableaulment00cuvi#page/142/mode/2up|pages=1–710}}</ref>

In 1861, [[Henri Marie Ducrotay de Blainville]] (1777–1850) classified ungulates by the structure of their feet, differentiating those with an even number of toes from those with an odd number. He moved the horses as ''solidungulate'' over to the tapirs and rhinos as ''multungulate'' animals and referred to all of them together as ''onguligrades à doigts impairs'', coming close to the concept of the odd-toed ungulate as a systematic unit. [[Richard Owen]] (1804–1892) quoted Blainville in his study on fossil mammals of the [[Isle of Wight]] and introduced the name ''Perissodactyla''.<ref name="Simpson 1945"/><ref name="Schoch 1989"/>

In 1884, [[Othniel Charles Marsh]] (1831–1899) came up with the concept ''[[Mesaxonia]]'', which he used for what are today called the odd-toed ungulates, including their extinct relatives, but explicitly excluding the hyrax. ''Mesaxonia'' is now considered a synonym of ''Perissodactyla'', but it was sometimes also used for the true odd-toed ungulates as a subcategory (rhinos, horses, tapirs), while ''Perissodactyla'' stood for the entire order, including the hyrax. The assumption that hyraxes were ''Perissodactyla'' was held well into the 20th century.<ref>{{cite book|author1=Donald R. Prothero|author2=Robert M. Schoch|chapter=Classification of the Perissodactyla|title=The Evolution of Perissodactyls |publisher=Oxford University Press |year=1989|pages=530–537}}</ref> Only with the advent of molecular genetic research methods had it been recognized that the hyrax was not closely related to perissodactyls but rather to elephants and manatees.<ref name="Graur et al. 1997"/><ref>{{cite journal|author1=Rodolphe Tabuce|author2=Laurent Marivaux|author3=Mohammed Adaci|author4=Mustapha Bensalah|author5=Jean-Louis Hartenberger|author6=Mohammed Mahboubi|author7=Fateh Mebrouk|author8=Paul Tafforeau|author9=Jean-Jacques Jaeger|title=Early Tertiary mammals from North Africa reinforce the molecular Afrotheria clade|journal=Proceedings of the Royal Society B|year=2007|pages= 1159–1166|doi=10.1098/rspb.2006.0229|volume=274|issue=1614|pmid=17329227|pmc=2189562}}</ref>