Consequently, the term "prosimian" is no longer widely used in a taxonomic sense, but is still used to illustrate the behavioral ecology of tarsiers relative to the other primates.

Being an evolutionary grade rather than a clade, the prosimians are united by being primates with traits otherwise found in non-primate mammals.

Their diets typically are less dominated by fruit than those of the simians, and many are active arboreal predators, hunting for insects and other small animals in the trees.

Related to their frequently nocturnal lifestyle, prosimians lack the colour vision of higher primates.

[13] Prosimians generally show lower cognitive ability and live in simpler social settings than the simians.

This relationship is shown by the ranks (prosimians in bold) in the list below of the current primate classification between the order and infraorder level.

The term "prosimian" is considered taxonomically obsolete,[16] although it is used to emphasize similarities between strepsirrhines, tarsiers, and the early primates.