WordNet (r) 3.0 (2006):

cainogenesis
    n 1: 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) [syn: cenogenesis,
         kenogenesis, caenogenesis, cainogenesis,
         kainogenesis] [ant: palingenesis, recapitulation]