Bird of prey and may be raised to an order of their own, Cathartiiformes. The secretary bird and/or osprey are sometimes listed as subfamilies of Acciptridae: Sagittariinae and Pandioninae, respectively. Australia's letter-winged kite is a member of the family Accipitridae, although it is a nocturnal bird. The nocturnal birds of prey – the owls – are classified separately as members of two extant families of the order Strigiformes: Below is a simplified phylogeny of Telluraves which is the clade where the birds of prey belong to along with passerines and several near-passerine lineages. The orders in bold text are birds of prey orders;
Genomic evolution of birds several modifications and deletions which occurred in the exons of the genes implicated in the formation of enamel and dentine. It is thought that the common ancestor of birds already lacked mineralized teeth, and that later genome changes pushed the situation to the current status. Also, birds have the best vision system known in vertebrates. They have a higher number of photoreceptors, and most birds are tetrachromats. The only exception are penguins, which have only three functional opsin genes (and hence are trichromats). This exception could be related to the aquatic lifestyle, since marine mammals have also lost either one