Editing Perissodactyla (section)

===Limbs===
[[File:Anatomy of the horses foot.jpg|thumb|Seven figures showing the bones, blood vessels, ligaments and arteries of the hoof and pastern.]]
The main axes of both the front and rear feet pass through the third toe, which is always the largest. The remaining toes have been reduced in size to varying degrees. Tapirs, which are adapted to walking on soft ground, have four toes on their fore feet and three on their hind feet. Living rhinos have three toes on both the front and hind feet. Modern equines possess only a single toe; however, their feet are equipped with hooves, which almost completely cover the toe. Rhinos and tapirs, by contrast, have hooves covering only the leading edge of the toes, with the bottom being soft.

[[Ungulate]]s have stances that require them to stand on the tips of their toes. [[Equinae|Equine]] ungulates with only one digit or hoof have decreased mobility in their limbs, which allows for faster running speeds and agility.
Differences in limb structure and physiology between [[ungulate]]s and other mammals can be seen in the shape of the [[humerus]]. For example, often shorter, thicker, bones belong to the largest and heaviest ungulates like the [[rhinoceros]].<ref>Hall, Brian K. (2006). Fins into Limbs. University of Chicago Press. ISBN 978-0-226-31337-5.</ref>

The [[ulna]]e and [[fibula]]e are reduced in horses. A [[autapomorphy|common feature]] that clearly distinguishes this group from other mammals is the articulation between the [[talus bone|astragalus]], the [[navicular|scaphoid]] and the [[Cuboid bone|cuboid]], which greatly restricts the mobility of the foot.<ref>{{Cite journal |last=Hussain |first=S. |date=September 1975 |title=Evolutionary and Functional Anatomy of the Pelvic Limb in Fossil and Recent Equidae (Perissodactyla, Mammalia) |url=http://dx.doi.org/10.1111/j.1439-0264.1975.tb00637.x |journal=Anatomia, Histologia, Embryologia: Journal of Veterinary Medicine Series C |volume=4 |issue=3 |pages=193–222 |doi=10.1111/j.1439-0264.1975.tb00637.x |pmid=1199544 |s2cid=34568531 |issn=0340-2096}}</ref><ref>{{Cite journal |last=Lorente |first=Malena |date=2019-08-02 |title=What are the most accurate categories for mammal tarsus arrangement? A review with attention to South American Notoungulata and Litopterna |url=http://dx.doi.org/10.1111/joa.13065 |journal=Journal of Anatomy |volume=235 |issue=6 |pages=1024–1035 |doi=10.1111/joa.13065 |pmid=31373392 |pmc=6875937 |issn=0021-8782}}</ref> The thigh is relatively short, and the [[clavicle]] is absent.