The elephants (Order Proboscidea, Infraclass Eutheria) exist currently as two genera in the subfamily Elephantinae: African elephants (2 species of genus Loxodonta) and Indian elephants (genus Elephas). The Elephantinae represents the crown group of the elephants, while the Proboscidea is a clade that comprises both the crown elephants and all members of the elephant stem group. The Proboscidea may thus be considered as the total group of elephants. 

The most extensive phylogenetic analysis available for the total-group Proboscidea is that presented by Baleka et al (2022). This analysis is the basis for the following phylogenetic time tree:
​Figure 1. Time tree of the stem-Elephantinae
​The oldest known member of the stem-Elephantinae is Daouitherium rebouli, described from the phosphate beds II/I of Early Eocene (Early Ypresian) age in a quarry at Sidi Chennane in the Ouled Abdoun Basin of Morocco (Gheerbrant et al, 2002; Heritage et al, 2021). Jawbones of this species are illustrated below, together with other stem-group fossils for which images are available in the public domain (click on image for a larger view):
Names in   red indicate   that the fossil is younger  than the oldest known crown-group fossil.
​​Figure 2. Images of stem-Elephantinae
​The above images are ordered from most basal to most crownward, and a general trend can be seen from smaller, pig-like forms to larger animals that progressively more closely resemble modern elephants. The most crownward genera that are obviously elephant-like are the mastodons (family Mammutidae), not to be confused with mammoths (genus Mammuthus), which are in the elephant crown group (family Elephantinae). The next most crownward clade, comprising the family Amebelodontidae, differ from modern elephants primarily in having shovel-like tusks on their lower jaw. Lower tusks are also seen in the more basal members of the clade Gomphotheriidae but not in the more derived members (Rhynchotherium through Stegomastodon and Notiomastodon).

The oldest known fossils of the elephant crown group are teeth from the genus Loxodonta (to which belongs the modern African elephant), described from sediments of Late Miocene age at Toros-Menalla site 266 (TM 266), a single locality in the Djurab Desert, northern Chad (Vignaud et al, 2002; Heritage et al, 2021). No images are available in the public domain.

The available fossil data indicate that the Elephantinae stem group developed from Early Eocene to Late Miocene time, representing a stem-to-crown transition of at least 48 million years (see Figure 1).

References

Baleka, S., Varela, L., Tambusso, P. S., Paijmans, J. L., Mothé, D., Stafford, T. W., ... & Hofreiter, M. (2022). Revisiting proboscidean phylogeny and evolution through total evidence and palaeogenetic analyses including Notiomastodon ancient DNA. IScience, 25(1).

Gheerbrant, E., Sudre, J., Cappetta, H., Iarochéne, M., Amaghzaz, M., & Bouya, B. (2002). A new large mammal from the Ypresian of Morocco: evidence of surprising diversity of early proboscideans. Acta Palaeontologica Polonica, 47(3).

Heritage, S., Seiffert, E. R., & Borths, M. R. (2021). Recommended fossil calibrators for time-scaled molecular phylogenies of Afrotheria. Afrotherian Conservation 17 https://www. afrotheria. net/newsletter. php.

Sanders, W.J., Gheerbrant, E., Harris, J.M., Saegusa, H., and Delmer, C. (2010). Proboscidea. In Werdelin, L., & Sanders, W. J. (2010). Cenozoic mammals of Africa. Univ of California Press, p. 161-251.

Shoshani, J., Golenberg, E. M., & Yang, H. (1998). Elephantidae phylogeny: morphological versus molecular results. Acta Theriologica, 43(Suppl. 5), 89-122.

Vignaud, P., Duringer, P., Mackaye, H. T., Likius, A., Blondel, C., Boisserie, J. R., ... & Brunet, M. (2002). Geology and palaeontology of the Upper Miocene Toros-Menalla hominid locality, Chad. Nature, 418(6894), 152-155.
Image credits – stem-Elephantinae
  • Header (African elephants, Kenya): Maryam Laura Moazedi, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
  • Figure 2 (Daouitherium rebouli): Ghedoghedo, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
  • Figure 2 (Numidotherium koholense): Sneaking stoat 2, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
  • Figure 2 (Moeritherium sp.): Momotarou2012, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
  • Figure 2 (Moeritherium lyonsi): Nobu Tamura, under Creative Commons Attribution- ShareAlike (CC BY-SA)  license
  • Figure 2 (Barytherium grave): Nobu Tamura, under Creative Commons Attribution- ShareAlike (CC BY-SA)  license
  • Figure 2 (Deinotherium giganteum, fossil): Alexxx1979, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
  • Figure 2 (Deinotherium giganteum, life restoration): Nobu Tamura, under a Creative Commons 3.0 Unported (CC BY-NC-ND 3.0) license
  • Figure 2 (Palaeomastodon beadnelli, fossil): Ghedoghedo, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons 
  • Figure 2 (Palaeomastodon beadnelli, life restoration): Nobu Tamura, under Creative Commons Attribution- ShareAlike (CC BY-SA)  license
  • Figure 2 (Phiomia serridens, fossil): Ghedoghedo, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
  • Figure 2 (Phiomia serridens, life restoration): Nobu Tamura, under Creative Commons Attribution- ShareAlike (CC BY-SA)  license 
  • Figure 2 (Zygolophodon sp.): 幽灵巴尼, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
  • Figure 2 (Mammut americanum, fossil): Photographed by Bob James (owner of website) at Houston Museum of Natural Science, March 2023.
  • Figure 2 (Mammut americanum, life restoration): Nobu Tamura, under Creative Commons Attribution- ShareAlike (CC BY-SA)  license
  • Figure 2 (Choerolophodon sp.): Ghedoghedo, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons 
  • Figure 2 (Archaeobelodon filholi): Ghedoghedo, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons 
  • Figure 2 (Serbelodon sp.): Gary Todd, CC0, via Wikimedia Commons
  • Figure 2 (Platybelodon grangeri, fossil): Gary Todd, under CC0 1.0 Universal (CC0 1.0) Public Domain Dedication 
  • Figure 2 (Platybelodon grangeri, life restoration): Nobu Tamura, under Creative Commons Attribution- ShareAlike (CC BY-SA)  license
  • Figure 2 (Amebelodon fricki): IJReid, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
  • Figure 2 (Amebelodon britti): DiBgd, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
  • Figure 2 (Gomphotherium productum): Photographed by Bob James (owner of website) at American Museum of Natural History, New York, May 2024
  • Figure 2 (Gomphotherium angustidens): Nobu Tamura, under Creative Commons Attribution- ShareAlike (CC BY-SA)  license
  • Figure 2 (Gnathabelodon thorpei): DiBgd, Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
  • Figure 2 (Eubelodon morrilli, fossil): James St. John, CC BY 2.0 <https://creativecommons.org/licenses/by/2.0>, via Wikimedia Commons
  • Figure 2 (Eubelodon morrilli, life restoration): Margret Flinsch, Public domain, via Wikimedia Commons
  • Figure 2 (Rhynchotherium falconeri): Joaquin Eng Ponce, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
  • Figure 2 (Skeletal reconstruction of Sinomastodon sp.): Asier Larramendi, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons
  • Figure 2 (Sinomastodon sp., life restoration): DiBgd, Creative Commons Attribution-Noncommercial-No Derivative Works 3.0 License
  • Figure 2 (Cuvieronius hyodon, fossil): Ghedo, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
  • Figure 2 (Cuvieronius hyodon, life restoration): DiBgd, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
  • Figure 2 (Stegomastodon mirificus): WolfmanSF, Public domain, via Wikimedia Commons
  • Figure 2 (Stegomastodon sp.): Joaquin Eng Ponce, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
  • Figure 2 (Skeletal reconstruction of Notiomastodon platensis): Asier Larramendi, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons
  • Figure 2 (Notiomastodon sp.): Pelegrin, J. S., Quijano, S. A., Belalcázar, L., Benavides-Herrán, A. ., Escobar-Flórez, S., Mothé, D., & Avilla, L. dos S, CC BY-SA 4.0 <https://creativecommons.org/licenses/by-sa/4.0>, via Wikimedia Commons
  • Figure 2 (Stegolophodon latidens): Ghedoghedo, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
  • Figure 2 (Tetralophodon sp.): Gary Todd, CC0, via Wikimedia Commons
  • Figure 2 (Anancus arvernensis, fossil): Ghedoghedo, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
  • Figure 2 (Anancus arvernensis, life restoration): Nobu Tamura, under Creative Commons Attribution- ShareAlike (CC BY-SA)  license
  • Figure 2 (Stegotetrabelodon syrticus): Nobu Tamura, under Creative Commons Attribution- ShareAlike (CC BY-SA)  license
  • Figure 2 (Stegodibelodon schneideri): Ghedoghedo, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
  • Figure 2 (Primelephas sp.): A. C. Tatarinov, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons