What are the difficulties that you would face in the classification of animals if common fundamental features are not taken into account?
For the classification of living organisms, common fundamental characteristics are considered.
If we consider specific characteristics, then each organism will be placed in a separate group and the entire objective of classification would not be achieved.
Classification of animals is also important in comparing different organisms and judging their individual evolutionary significance. If only a single character is considered, then this objective would not be achieved.