''Exiguodon'' ("strict tooth") is an

extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of hyainailourid

hyaenodont Hyaenodonta ("hyena teeth") is an extinct order of hypercarnivorous placental pan-carnivoran mammals from mirorder Ferae. Hyaenodonts were important mammalian predators that arose during the early Paleocene in Europe and persisted well into the ...

mammal of the

polyphyletic A polyphyletic group is an assemblage of organisms or other evolving elements that is of mixed evolutionary origin. The term is often applied to groups that share similar features known as homoplasies, which are explained as a result of converg ...

tribe

Hyainailourini Hyainailourini ("hyena-cats") is an extinct polyphyletic tribe of hyainailourid hyaenodonts from paraphyletic subfamily Hyainailourinae that lived in Africa, Asia and Europe during the middle Eocene to middle Miocene. Classification and phyloge ...

within

paraphyletic In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...

subfamily

Hyainailourinae Hyainailourinae ("hyena-cats") is an extinct paraphyletic subfamily of hyainailourid hyaenodonts that lived in Africa, Asia, North America and Europe during the middle Eocene to middle Miocene. Classification and phylogeny Taxonomy * Subfamily: ...

. Remains are known from early

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

deposits in

Kenya ) , national_anthem = "Ee Mungu Nguvu Yetu"() , image_map = , map_caption = , image_map2 = , capital = Nairobi , coordinates = , largest_city = Nairobi , ...

and

Uganda }), is a landlocked country in East Africa East Africa, Eastern Africa, or East of Africa, is the eastern subregion of the African continent. In the United Nations Statistics Division scheme of geographic regions, 10-11-(16*) territor ...

, in

East Africa East Africa, Eastern Africa, or East of Africa, is the eastern subregion of the African continent. In the United Nations Statistics Division scheme of geographic regions, 10-11-(16*) territories make up Eastern Africa: Due to the historical ...

Description

''Exiguodon'' is distinguished from other hyainailourines by the following features: diminutive dimensions, lower molars (m3 – m2) with greatly reduced talonid; protoconid and paraconid similar in size. Paraconid of the molars lingually oriented. M2 and M1 close in size and morphology. Occlusal outline sub-triangular, with greatly reduced protocone, which appears like an antero-lingual cingulum which extends anteriorly and buccally. Presence of a strong parastyle in an antero-buccal position, united to the apex of the paracone by a well defined crista. The buccal cingulum borders a wide buccal platform, particularly large in the M2. Paracone tall and narrow, elongated blade-like metastyle. P4 broadened, with reduced protocone and presence of a notch between the main conical cusp and the blade-like posterior cusp.

Classification and phylogeny

Taxonomy

''Exiguodon pilgrimi'' was originally described as ''Hyaenodon (Isohyaenodon) pilgrimi'' by R. J. G. Savage (1965), who coined ''

Isohyaenodon ''Isohyaenodon'' ("equal to Hyaenodon") is an extinct polyphyletic genus of hyainailourid hyaenodont mammal from polyphyletic subtribe Isohyaenodontina (of the polyphyletic tribe Hyainailourini within paraphyletic subfamily Hyainailourinae). Re ...

'' as a subgenus of ''

Hyaenodon ''Hyaenodon'' (" hyena-tooth") is an extinct genus of carnivorous hyaenodont mammals from tribe Hyaenodontini, within subfamily Hyaenodontinae in family Hyaenodontidae,Malcolm C. McKenna, Susan K. Bell (1997."Classification of Mammals: Above t ...

''. Later authors recognized ''Isohyaenodon'' as distinct from ''Hyaenodon'', and Morales and Pickford (2017) eventually realized that ''pilgrimi'' was sufficiently distinct from all other African hyainailourines to warrant its own genus, which they named ''Exiguodon''.

Phylogeny

The phylogenetic relationships of genus ''Exiguodon'' are shown in the following cladogram:

References

Hyaenodonts Miocene mammals of Africa Prehistoric placental genera {{paleo-mammal-stub