Usage: capitalized
in many classifications : a suborder of Marsupialia comprising the kangaroos, phalangers, koala, wombats, the extinct giants of the genus Diprotodon, and other marsupials that are all almost exclusively herbivorous, have only one well-developed pair of lower incisors, but usually have three pairs of upper incisors — compare polyprotodontia
Useful english dictionary. 2012.