Editing Desmostylia (section)

==Description==
[[File:Desmostylia skeletal diagram (to scale).png|center|thumb|655x655px|Skeletal diagrams: (A) ''[[Ashoroa]]'', (B) ''[[Desmostylus]]'', (C) ''[[Behemotops|Behemetops]]'', (D) ''[[Paleoparadoxia]]'']]
Desmostylians were large, fully aquatic quadrupeds with massive limbs and short tails.<ref name="Gheerbrant-etal-2005" /> The smallest is ''[[Ashoroa laticosta]]'', a relatively large animal at a body length of {{convert|168|cm|ftin|0|disp=or}}, while the largest species reached sizes comparable to [[Steller's sea cow]].<ref name="Nicholas D. Pyenson 2016">[[Nicholas D. Pyenson]], Geerat J. Vermeij, The rise of ocean giants: maximum body size in Cenozoic marine mammals as an indicator for productivity in the Pacific and Atlantic Oceans, Published 5 July 2016.DOI: 10.1098/rsbl.2016.0186</ref>

A desmostylian skull has an elongated and broadened [[Rostrum (anatomy)|rostrum]], with the nasal opening located slightly dorsally. The [[zygomatic arch]]es are prominent (behind the eyes), the [[paroccipital process]]es elongated (downward-pointing processes behind the jaw-joints), and the [[epitympanic sinus]]es open into the [[temporal fossa]]e (cavities above the ear holes).<ref name="Gheerbrant-etal-2005" />

The mandible and maxilla typically have forward-pointing incisors and canine tusks, followed by a long postcanine diastema, partly because of the reduced number of premolars. The cusps of the premolars and molars are composed of densely packed cylinders of thick enamel, giving the order its name ("bundle of columns"). The primitive dental formula is 3.1.4.3, with a trilobate fourth deciduous premolar. The cheek teeth are [[brachydont]] and [[bunodont]] in primitive genera, but [[hypsodont]] in later genera such as ''Desmostylus'', which has many supernumerary cusps.<ref name="Gheerbrant-etal-2005" />

In the [[postcrania]], the [[clavicle]] is absent and the [[sternum]] consists of a series of heavy, paired, plate-like sternebrae. In adults, the joints between the radius and ulna prevent any movements. The metacarpals are longer than metatarsals, and each foot has four digits (digit I is vestigial).<ref name="Gheerbrant-etal-2005" />