Phenetic versus Cladistic perception &
classification of Birds
Given the phylogeny at top left, a traditional phenetic classification scheme (above, middle) emphasizes the perceived dissimilarity of birds from scaly tetrapods like lizards and crocodiles, whereas a cladistic scheme (above, right) will emphasize the more recent common ancestry of birds with crocodiles.
Modern phylogenetic
classifications emphasize character analyses, which
show that birds evolved from dinosaurs. For example,
crocodiles, birds, and (presumably) dinosaurs have four-chambered
hearts and vocalizations, unlike lizards.That is,
perceptions of bird distinctiveness from dinosaurs have
changed. However, popular discussions, such "Jurassic
Park", present this change in perception as showing
that "dinosaurs are more similar to birds." That is,
perceptions of dinosaur "primitiveness"
have changed. This "neo-phenetic" analysis (left &
middle, below) produces the phylogenetic pattern from phenetic
criteria. The cladistic classification remains unchanged
(below, right).
A note on
terminology: systematists favoring a combination of
phenetic and cladistic approaches versus those of use only
cladistics, both claim to be doing phylogenetic taxonomy.
This term is now associated with cladistic taxonomy,
whereas phenetics remains associated with 'traditional' taxonomy.