Mammuthus subplanifrons

Mammuthus subplanifrons is the oldest representative of the genus Mammuthus, known from around 6.2-3.75 million years ago during the late Miocene-early Pliocene in what is today South Africa and countries of East Africa, especially Ethiopia. They already presented some of the unique characteristics of mammoths like the spirally, twisting tusks.

Taxonomy
The species was first named as Archidiskodon subplanifrons by Henry Fairfield Osborn in 1928. The type specimen is a partial lower third molar (MMK 3920) collected from the Vaal River in South Africa. However, it has been subsequently argued that this specimen does not actually belong to Mammuthus, but instead is actually a specimen of Loxodonta, and thus a neotype should be selected that actually belongs to Mammuthus. The species is primarily known from dental remains.  A 2016 study attributed the skull and partial skeleton KNM-KP 385 to the species, but this in error and actually represents the holotype skeleton of ''Loxodonta adaurora.  In 2009, it was suggested that Loxodonta adaurora is indistinguishable from Mammuthus subplanifrons''. However, other authors have continued to regard the species as distinct, and contend that the similarities between the two species are superficial.  Tusks attributed to the species suggest that they were twisted like later mammoth species.  

Distribution and chronology
Specimens have been reported from South Africa, Kenya, Ethiopia, Malawi, and possibly Uganda and the Democratic Republic of the Congo, spanning from around 6.2 to 3.75 million years ago.  Specimens intermediate between M. subplanifrons and the later species Mammuthus africanavus have been reported from the Late Pliocene Hadar Formation, Ethiopia, dating to around 3.5 million years ago.

Ecology
Isotope analysis of specimens from South Africa suggests that M. subplanifrons was a flexible feeder.