snow leopard is nested within Panthera and is the sister species of the tiger. Results of a 2016 study based on analysis of biparental nuclear genomes suggest the following relationships of living Panthera species: The extinct European jaguar (Panthera gombaszogensis), was probably closely related to the modern jaguar. The first fossil remains were excavated in Olivola, in Italy, and date to . Fossil remains found in South Africa that appear to belong within the Panthera lineage date to about . Classification During the 19th and 20th centuries, various explorers and staff of natural history museums suggested numerous subspecies, or at times called "races", for all Panthera species. The taxonomist Reginald Innes Pocock reviewed skins and skulls in the zoological collection of the Natural History Museum, London, and grouped subspecies described, thus shortening the lists considerably. Since the mid-1980s, several Panthera species became subjects of genetic research, mostly using blood samples of captive individuals. Study results indicate that many of the lion and leopard subspecies are questionable because of insufficient genetic distinction between them. Subsequently, it was proposed to group all African leopard populations to P. p. pardus and retain eight subspecific names for Asian leopard populations. Based on genetic research, it was suggested to group all living sub-Saharan lion populations into P. l. leo. Results of phylogeographic studies indicate that the Western and Central African lion populations are more closely related to those in India and form a different clade than lion populations in Southern and East Africa; southeastern Ethiopia is an admixture region between North African and East African lion populations. Black panthers do not form a distinct species, but are melanistic specimens of the genus, most often encountered in the leopard and jaguar. Contemporary species The following list of the genus Panthera is based on the taxonomic assessment in Mammal Species of the World and reflects the taxonomy revised in 2017 by the Cat Classification Task Force of the Cat Specialist Group: Extinct species and subspecies Other, now invalid, species have also been described, such as Panthera crassidens from South Africa, which was later found to be based on a mixture of leopard and cheetah fossils. Phylogeny The cladogram below follows Mazák, Christiansen and Kitchener (2011). In 2018, results of a phylogenetic study on living and fossil cats were published. This study was based on the morphological diversity of the mandibles of saber-toothed cats, their speciation and extinction