Manouria is either the most basal or second most basal member of the family Testudinidae (its phylogenetic position is adjacent to that of Gopherus).[1][2] As a result, while tortoises are primarily terrestrial, the genus Manouria is a model for the evolutionary transition to terrestriality, as it still has an affinity for aquatic environments, and has retained some ancestral adaptations for an aquatic lifestyle while losing others. The Asian forest tortoise (Manouria emys) has been observed attempting to feed on submerged food items, albeit unsuccessfully. Additionally, the species grasps food item with its jaws as in aquatic or semiaquatic taxa, as opposed to first making contact with the tongue as with all other tortoise species (with the possible exception of Gopherus).[3]
^Staesche, Ulrich (coordinator) (2007). Fossile Schildkröten aus vier Ländern in drei Kontinenten: Deutschland, Türkei, Niger, Philippen [= Fossil Turtles from Four Countries on Three Continents: Germany, Turkey, Niger, and the Philippines]. Geologisches Jahrbuch, Reihe B, Heft 98 [= Series B, Issue 98]. 197 pp. ISBN978-3-510-95967-9. http://www.schweizerbart.de/publications/detail/artno/186029800 (in German).
Gray, J. E. (1854). "Description of a New Genus and some New Species of Tortoises". Proceedings of the Zoological Society of London. 1852: 133–135. (Manouria, new genus, p. 133).