Systemic grounds of morphogenesis and their manifestation in the fossil record

Morphogenetic mechanisms form an integrity purposed to secure the due course of ontogeny towards the adult norm. This purposefulness is a principal feature of living organization that requires an explanation. Each step in evolution is a compelled reorganization of the ontogenetic system towards a new ultimate goal (system’s equilibrium state), i.e., a new norm. An increase in stability of realization of the latter, caused by natural selection, results in progressive remodeling of ontogeny of the evolutionary novelty which spreads in succeeding life cycles towards the earlier stages. As a result, the difference between current ontogenetic record of the novelty and the ancestral developmental pattern tends to change more and more from the prolonging (recapitulative) to divergent one, corresponding to Baer’s law. In the fossil record, the changes caused by these stabilizing processes result in a number of manifestations, such as initially labile expression of new acquisitions, the remodeling of their morphogenesis with time and the predominant maintenance of ancestral traits in late ontogeny of the closest descendants.