Starting from a given morphology, adaptation to different lifestyles and environments involves the modification of structures through natural selection.
The dentition of carnivores is a clear example of this. To quantify the degree of divergence in the dentition of current carnivore families, the dentition has been divided into different regions (canines, premolars, carnassials and molars) and standardized for size by dividing by the total area of the dentition.
Morphological divergence quantified as the distance from the centroid of the entire order or from that of each family is generally greater for the upper dentition than for the lower dentition. This suggestsdifferential selection pressures on the upper and
lower dentition to adapt members of the order Carnivora to the different niches they occupy. This, which seems obvious for the machairodontine felids, is also observed in all other living families of both
feliforms and caniforms.