Primitive (phylogenetics)

Primitive (or ancestral) in phylogenetics means a character, trait or feature of a lineage or taxon that is inherited from the common ancestor of a clade (or clade group) and has undergone little change since. Conversely, a trait that appears within the clade group (that is, is present in any subgroup within the clade but not all) is called advanced or derived. A clade is a group in which all members have the same common ancestor.