CoachA character is a feature that varies among the species compared (the presence of a vertebral column, of four limbs, of an amniotic egg, of hair). Each character has an ancestral state — the one the common ancestor of the group had — and one or more derived states that appeared later in some lineage. Only shared derived states indicate kinship: two species sharing a derived state inherited it from the ancestor in which it arose. A shared ancestral state says nothing, since everyone’s ancestor had it.
