Evolutionary tree
cladistics; where more than two groups are shown in a single branch, there is disagreement about how they diverged. Hypothetically taxonomy would follow the tree whenever possible, but in many places it does not at present.
The description as a "tree" results from earlier ideas of life as a progression from lower to higher forms. Although such views are discredited now, the imagery is too well established to be readily lost.
The terminology originates with Linnaean taxonomy: living things are classified as belonging to domain, kingdom, phylum, class, order, family, genus and species.
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