Ferae

Pangolins were long thought to be the closest relatives of Xenarthra (armadillos, anteaters, and sloths), contributing to the polyphyletic group of Edentata. Research based on immunodiffusion technique[11] and comparison of protein and DNA sequences[12][13][14] revealed the close relationships between pangolins and carnivorans. Living pangolins and carnivorans also share few unusual derived morphological and anatomical traits, such as the ossified tentorium cerebelli and the fusion of the scaphoid and lunate bones in the wrist.[15]

According to recent studies (reflected in the diagram below), the closest relatives of Ferae are Perissodactyla (horses, tapirs, and rhinos) and Cetartiodactyla (which combines Artiodactyla—camels, pigs, ruminants and hippos—with Cetacea—whales and dolphins).[16][17] An alternate phylogeny (less supported) holds that the closest relatives to the Ferae are the Perissodactyla and Chiroptera (bats), not Cetartiodactyla.[18] Ferae together with Perissodactyla has been called Zooamata. Ferae, Perissodactyla, and Chiroptera together has been called Pegasoferae.

While there has been strong support in the inclusion of creodonts into Ferae, they were usually recovered as sister taxon to Carnivoramorpha (carnivorans and their stem-relatives).[19] The Halliday et al. (2015) phylogenetic analysis of hundreds of morphological characters of Paleocene placentals found instead that creodonts might be the sister group to Pholidotamorpha (pangolins and their stem-relatives).[5] However, recent studies have show Creodonta is polyphyletic clade and sister taxon to Carnivoramorpha, split in two groups: order Oxyaenodonta on one side and order Hyaenodonta plus stem-relatives (Altacreodus and Tinerhodon) on the other.[20][8][9][10][21]

After Halliday et al. (2015) various enigmatic Palaeocene mammals have been found to be possible members to Ferae, like members of suboders Pantodonta and Taeniodonta, and families Didelphodontidae, Nyctitheriidae, Oxyclaenidae, Palaeoryctidae, Pantolestidae, Pentacodontidae, Periptychidae, Triisodontidae and Wyolestidae.[5] In addition various supposedly "hoofed mammals" like the mesonychians and arctocyonids (usually considered as stem-artiodactyls[22]) also belong to the group. In addition, Mesonychians might be the sister group to carnivoramorphs, while arctocyonids are polyphyletic with Arctocyon and Loxolophus sister to pantodonts and periptychids, Goniacodon and Eoconodon sister to the Carnivoramorpha-Mesonychia clade, most other genera allied with creodonts and palaeoryctidans, and Protungulatum not a placental mammal.[5] This enlarged Ferae was also found to be the sister group to Chiroptera.[5]

Below is a phylogeny of the interrelationships within Ferae among the various extant and fossil groups, as well as their sister placement to Chiroptera after Halliday et al. (2015):[5]