KENOGENESIS
cenogenesis, kenogenesis, caenogenesis, cainogenesis, kainogenesis
(noun) introduction during embryonic development of characters or structure not present in the earlier evolutionary history of the strain or species (such as the addition of the placenta in mammalian evolution)
Source: WordNet® 3.1
Noun
kenogenesis (uncountable)
Alternative form of caenogenesis
Source: Wiktionary
Ken`o*gen"e*sis, n. Etym: [Gr. genesis.] (Biol.)
Definition: Modified evolution, in which nonprimitive characters make their
appearance in consequence of a secondary adaptation of the embryo to
the peculiar conditions of its environment; -- distinguished from
palingenesis. [Written also cænogenesis.]
Source: Webster’s Unabridged Dictionary 1913 Edition