Editing Perissodactyla (section)

{{Short description|Order of hoofed mammals}}
{{Use dmy dates|date=October 2020}}
{{more citations needed|date=October 2021}}
{{Automatic taxobox
| name = Perissodactyla
| fossil_range = {{Fossil range|56|0|earliest=59.2}}[[Paleocene|Latest Paleocene]]–[[Holocene|present]]<ref>{{Cite web|title=PBDB|url=https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=42980&is_real_user=1|access-date=2021-07-18|website=paleobiodb.org}}</ref>
| image = The Perissodactyl.jpg
| image_caption = Clockwise from left: [[plains zebra]] (''Equus quagga''), [[Indian rhinoceros]] (''Rhinoceros unicornis'') and [[South American tapir|Brazilian tapir]] (''Tapirus terrestris'')
| taxon = Perissodactyla
| authority = [[Richard Owen|Owen]], 1848
| subdivision_ranks = Families
| subdivision = *{{extinct}}[[Hyopsodontidae]]<ref>{{cite journal | last1 = Ravel | first1 = Anthony | last2 = Orliac | first2 = Maeva | year = 2014 | title = The inner ear morphology of the 'condylarthran' Hyopsodus lepidus | journal = Historical Biology | volume = 27 | issue = 8| page = 8 | doi = 10.1080/08912963.2014.915823 | s2cid = 84391276 }}</ref>
*{{extinct}}[[Brontotheriidae]] (brontotheres)
*'''Hippomorpha'''
**'''Equoidea'''
***[[Equidae]] (horses, asses, and zebras)
***{{extinct}}[[Palaeotheriidae]]
*'''Tapiromorpha'''
**{{extinct}}[[Isectolophidae]]
**{{extinct}}'''[[Ancylopoda]]'''
***{{extinct}}[[Chalicotherioidea]]
****{{extinct}}[[Chalicotheriidae]] (chalicotheres)
****{{extinct}}[[Eomoropidae]]
***{{extinct}}[[Lophiodontidae]]
**'''Ceratomorpha'''
***[[Tapiroidea]]
****{{extinct}}[[Deperetellidae]]
****{{extinct}}[[Helaletidae]]
****[[Tapiridae]] (tapirs)
***[[Rhinocerotoidea]] (rhinoceroses ''sensu lato'')
****{{extinct}}[[Amynodontidae]]
****{{extinct}}[[Hyracodontidae]]
****{{extinct}}[[Paraceratheriidae]]
****{{extinct}}[[Eggysodontidae]]
****[[Rhinocerotidae]] (rhinoceroses ''sensu stricto'')
}}
[[File:Rhinoceros male 2003.jpg|thumb|The [[white rhinoceros]] is the largest living perissodactyl]]

'''Perissodactyla''' ({{IPAc-en|p|ə|ˌ|r|ɪ|s|oʊ|ˈ|d|æ|k|t|ᵻ|l|ə}}, {{etymology|grc|''περισσός'', perissós|odd||''δάκτυλος'', dáktylos|finger, toe}}<ref>{{cite web|url=https://research.amnh.org/paleontology/perissodactyl/concepts/glossary|archive-url=https://web.archive.org/web/20211120123130/https://research.amnh.org/paleontology/perissodactyl/concepts/glossary|archive-date=20 November 2021|title=Glossary. American Museum of Natural History}}</ref>), or '''odd-toed ungulates''', is an order of [[Ungulate|ungulates]]. The order includes about 17 living [[species]] divided into three [[Family (biology)|families]]: [[Equidae]] ([[wild horse|horse]]s, [[Asinus|asses]], and [[zebra]]s), Rhinocerotidae ([[rhinoceros]]es), and Tapiridae ([[tapir]]s). They typically have reduced the weight-bearing toes to three or one of the five original toes, though tapirs retain four toes on their front feet. The nonweight-bearing toes are either present, absent, [[Vestigiality|vestigial]], or positioned posteriorly. By contrast, [[Artiodactyl|artiodactyls]] (even-toed ungulates) bear most of their weight equally on four or two (an even number) of the five toes: their third and fourth toes. Another difference between the two is that perissodactyls digest plant [[cellulose]] in their [[intestines]], rather than in one or more [[stomach]] chambers as artiodactyls, with the exception of [[Suina]], do.

The order was considerably more diverse in the past, with notable extinct groups including the [[Brontotheriidae|brontotheres]], [[Palaeotheriidae|palaeotheres]], [[Chalicotheriidae|chalicotheres]], and the [[Paracerathere|paraceratheres]], with the paraceratheres including the largest known land mammals to have ever existed.

Despite their very different appearances, they were recognized as related families in the 19th century by the zoologist [[Richard Owen]], who also coined the order's name.