Phylogeny pertains to the evolutionary history of a taxonomic group of organisms. Thus, phylogenetics is mainly concerned with the relationships of an organism to other organisms according to evolutionary similarities and differences. Ontogeny is the development of a single individual, or a system within the individual, from the fertilized egg to maturation and death. Ancestry represents persons initiating or comprising a line of descent. Palaeontology is the study of the history of life on Earth as based on fossils.
Related Theory
The biogenelic law was proposed by Ernst Haeckel which states that each embryo's developmental stage represents an adult form of an evolutionary ancestor i.e., an organism, in the course of its development, goes through all the stages of those forms oflife from which it has evolved.