Answer:
Taxonomy is the branch of biology related to the identification and names of organisms. The Greek philosopher Aristotle was the one who apparently began the discussion on taxonomy. The British naturalist John Ray is credited with reviewing the concept of how to name and describe organisms. In the 18th century, the Swiss botanist, Carolus Linneus classified all known organisms into two large groups: the Plantae and Animalia kingdoms. Robert Whittaker in 1969 proposed five kingdoms: Plantae, Animalia, Fungi, Protista, and Monera. Other schemes were proposed proposing more kingdoms, however most biologists employ that of the five kingdoms. Recent studies suggest that three domains should be used: Archaea, Bacteria, and Eukarya and include a new kingdom of the archibacteria.
to trace the lineage of the birds from their ancestors the dinosaurs. The nodes or branching points indicate the appearance of a line that brings together a new series of derived characters (evolutionary developments). In this cladogram the Therapoda come from a precursor dinosurium that already had hollow bones and three fingers. They are still dinosaurs, a subgroup of Saurischia. Each line or clade is included in a larger one (colored rectangles that represent "nested sets"), so the birds are manirraptores, tetanuros and theropod dinosurios. Modified from: (Research and Science, The origin of birds and their flight, K. Padian and L.M Chiappe, April 1998.
An interesting and entertaining story about the contribution of whether birds originate from dinosaurs or not is found in Research and Science, The origin of birds and their flight, K. Padian and L.M Chiappe, April 1998.
The value of cladistics consists in the generation of multiple hypotheses (alternative cladograms) that can be evaluated with additional data, all in a parsimonious context (the smallest number of stages is considered the most correct). An important issue .... is evolution always parsimonious?
The cladist rigor introduced in the systematics is useful for traditional systematics to observe their subjective classifications with a new light. In the diagram below, shared derived characters are indicated as marks that cross the line. The clade of the mammals is united by the hair, the clade lizard, dove, mouse-chimpanzee by claws or nails, etc.