Elephantiformes is a

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

within the order

Proboscidea Proboscidea (; , ) is a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. Three l ...

. Members of this group are primitively characterised by the possession of upper tusks, an elongated

mandibular symphysis In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: ''symphysis menti'') or line of junction where the two lateral ha ...

(the frontmost part of the lower jaw) and lower tusks, and the retraction of the facial region of the skull indicative of the development of a trunk. The earliest known member of the group, '' Dagbatitherium'' is known from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

(

Lutetian The Lutetian is, in the geologic timescale, a stage (stratigraphy), stage or age (geology), age in the Eocene. It spans the time between . The Lutetian is preceded by the Ypresian and is followed by the Bartonian. Together with the Bartonian it ...

) of

Togo Togo, officially the Togolese Republic, is a country in West Africa. It is bordered by Ghana to Ghana–Togo border, the west, Benin to Benin–Togo border, the east and Burkina Faso to Burkina Faso–Togo border, the north. It is one of the le ...

, which is only known from isolated teeth, while other primitive elephantiforms like '' Phiomia'' and '' Palaeomastodon'' are known from the

Early Oligocene The Rupelian is, in the geologic timescale, the older of two age (geology), ages or the lower of two stage (stratigraphy), stages of the Oligocene epoch (geology), Epoch/series (stratigraphy), Series. It spans the time between . It is preceded b ...

onwards. ''Phiomia'' and ''Palaeomastodon'' are often collectively referred to as "palaeomastodonts" and assigned to the family Palaeomastodontidae. Most diversity of the group is placed in the subclade Elephantimorpha, which includes mastodons (family Mammutidae), as well as modern elephants and

gomphotheres Gomphotheres are an extinct group of proboscideans related to modern Elephant, elephants. First appearing in Africa during the Oligocene, they dispersed into Eurasia and North America during the Miocene and arrived in South America during the Ple ...

(

Elephantida Elephantimorpha is a clade of proboscideans that contains the Mammutidae (mastodons), as well as Elephantida ( amebelodonts, choerolophodonts, gomphotheres, stegodontids and elephantids). All members of Elephantimorpha have the horizontal toot ...

), which are distinguished from more primitive elephantiforms by the development of horizontal tooth replacement. It is disputed as to whether ''Phiomia'' is closely related to both Mammutidae and

with ''Palaeomastodon'' being more basal, or if ''Palaeomastodon'' is closely related to Mammutidae and ''Phiomia'' more closely related to Elephantida. Phylogeny of Proboscidea including Elephantiformes, following Hautier et al. 2021

References

Mammal suborders {{afrotheria-stub