kenogenesis

from The Century Dictionary.

• noun Vitiated evolution, as distinguished from hereditary evolution; ontogenesis modified by adaptation, and therefore not true to its type; that development of an individual germ which does not truly epitomize and repeat the phylogenetic evolution of its race or stock: the opposite of palingenesis. See biogeny. Also kenogeny.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Biol.) 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.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun Alternative form of caenogenesis.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• 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)