Puffinus be divided in what has been called the "Puffinus" and the "Neonectris" group after notable species; the latter has been separated as a distinct genus named "Ardenna". The former is taxonomically confusing, with species having been split and remerged in the last years. The genus "Puffinus" contains the following species: Several fossil species which became extinct long ago are also known. The proportion of larger ("Neonectris") species apparently was larger before the Pliocene, i.e. before marine mammals diversified: ""Puffinus" arvernensis" (Early Miocene of France) is now considered a primitive albatross of the fossil genus "Plotornis". Puffinus Puffinus is a genus
Procellariidae with "Pseudobulweria" being phylogenetically closer to the "Puffinus" shearwaters than the "Pterodroma" gadfly petrels, and "Aphrodroma" (the Kerguelen petrel) possibly being closely related to the shearwaters or the fulmars. The prions, according to Nunn and Stanley, were among the larger shearwater group. The "Calonectris" shearwaters were placed close to the two "Puffinus" clades (closer to the Puffinus, or small, clade) and both were distant to the "Procellaria" shearwaters. The relationships between the genera and within the genera are still the subject of debate, with researchers lumping and splitting the species and genera within the family and arguing about the position