Both neoteny and progenesis result in paedomorphism (as having the form typical of children) or paedomorphosis (changing towards forms typical of children), a type of heterochrony. It is the retention in adults of traits previously seen only in the young. Such retention is important in evolutionary biology, domestication and evolutionary developmental biology. Some authors define paedomorphism as the retention of larval traits, as seen in salamanders.Schell, S. C. Handbook of Trematodes of North America North of Mexico, 1985, pg. 22Ginetsinskaya, T.A. Trematodes, Their Life Cycles, Biology and Evolution. Leningrad, USSR: Nauka 1968. Translated in 1988, .
