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Tyler's mouse opossum (Marmosa tyleriana) is a South American marsupial of the family Didelphidae.<ref name=msw3>Template:MSW3 Didelphimorphia</ref> It lives in rainforests of the Guiana Highlands of southern Venezuela at elevations between 1300 and 2200 m.<ref name="iucn status 19 November 2021" /> The species has only been found on three isolated tepuis (Auyantepui, Marahuaca and Sarisariñama).<ref name="iucn status 19 November 2021" /> All three of these locations are in protected areas (Canaima, Duida-Marahuaca and Jaua-Sarisariñama national parks).
The Latin species name refers to the habitat in which the opossum was first found, a Tyleria forest. In turn, both the genus Tyleria and the opossum's common name refer to Sidney F. Tyler, an American historian and photographer who helped finance the 1928-29 expedition of the American Museum of Natural History to the headwaters of the Orinoco, during which the opossum was discovered.<ref name = "Eponym">Template:Cite book</ref>