Rodents make up the largest order of mammals, with over 40% of mammalian species. They have two incisors in the upper and lower jaw which grow continually and must be kept short by gnawing.
The bats' most distinguishing feature is that their forelimbs are developed as wings, making them the only mammals capable of flight. Bat species account for about 20% of all mammals.
^This list is derived from the IUCN Red List which lists species of mammals and includes those mammals that have recently been classified as extinct (since 1500 AD). The taxonomy and naming of the individual species is based on those used in existing Wikipedia articles as of 21 May 2007 and supplemented by the common names and taxonomy from the IUCN, Smithsonian Institution, or University of Michigan where no Wikipedia article was available.
^McDonald, R. A.; Abramov, A. V.; Stubbe, M.; Herrero, J.; Maran, T.; Tikhonov, A.; Cavallini, P.; Kranz, A.; Giannatos, G.; Kryštufek, B. & Reid, F. (2019). "Mustela nivalis". IUCN Red List of Threatened Species. 2019: e.T70207409A147993366.