Phylogenetic or Cladistic Classification
Phylogeny plays a great role in classification. It is the appropriate theoretical background for taxonomy and is quite essential in explaining all the associations involved in classification. Some people believe phylogenetic and evolutionary classification are similar to each other since they both are based on the features derived from a common ancestor while some other consider as different approaches. Cladistic classification is exclusively based on phylogenetic branching. Cladistic phylogeny, in opposition to numerical phenetics, includes an attempt to map the sequence of phyletic branching through a determination of characters that are shared primitive (symplesiomorphic) and shared derived (synapomorphic).But, to date there is no true phylogenetic classification for any group of animals except (to some extent) that of horses. This is due to incomplete fossil record and also becausethe comparative data collected through other approaches fail to possibly give a clear picture by itself. Thus, cladistic taxonomic system attempts to communicate only genealogy. There is no attempt to express the degree of overall similarity of the organisms in such classification systems.