Polyphyletic does not embrace the common ancestor of the members of the group wherein those two members have two or more separate origins. It also signifies where certain group does not include the common ancestor in all members of the taxon that unrelated organisms descend from more than one ancestor. Like for example the flying vertebrates are polyphyletic since bats and birds are separately developed flight yet does not share a common ancestor.
Polyphyletic is when two organs came from two primitive forms and these forms belong to the same morphological series thereby shows incomplete homology but of parallel development as a consequent the phylogeny is not the same.
Some scientific researcher tries to avoid homoplasies in grouping species and usually discard groups that are polyphyletic since it affects in classification scheme. Intaxonomy polyphyletic groups are generally avoided and can be delimited in terms of clade wherein most of taxonomist rejects the use of polyphyletic taxa.
• polyphyly (noun)
• polyphyletically (adverb)