BAUPLAN

'Bauplan' (German for ''building plan'', ''blueprint''; plural: ''baupläne'' or ''bauplaene'') is a term in biology referring to the common new and original (homologous) properties of the members of a systematic group (taxon). It is not necessary that a bauplan precisely describes any one particular species of that group.
The concept of bauplan is employed in the studies of morphology, taxonomy, comparative physiology and, most notably, phylogenetics and evolution. Before the advent of genetic sequencing, the analysis of the bauplan of fossils was an important method to devise hypothetical relationships and lineages of species, both living and extinct. The idea is, that species that are closely related share more common properties, hence a more detailed bauplan. Small differences of bauplan are indicative of species belonging to a parent, child or sibling taxon.