Elephas

Elephas Temporal range: Pliocene to present
Asian elephant
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Proboscidea
Family:	Elephantidae
Tribe:	Elephantini
Genus:	Elephas Linnaeus, 1758
Type species
Elephas maximus Linnaeus, 1758
Species
8; see text
Synonyms
Hypselephas

Elephas is one of two surviving genera in the family of elephants, Elephantidae, with one surviving species, the Asian elephant, Elephas maximus.^[1] Several extinct species have been identified as belonging to the genus, extending back to the Pliocene era.

Description

Species of Elephas have distinct bossing of the parieto-occipital region of the skull. The premaxillae bones containing the tusks are tapered.^[2]

Evolutionary history

Asian elephants share a closer common ancestry with mammoths (genus Mammuthus) than they do with African elephants (Loxodonta).^[3] The oldest species attributed to the genus are known from the early-mid Pliocene (5–4.2 million years ago) of Africa, like Elephas ekorensis,^[4] though the attribution of this species to Elephas has been questioned.^[5] The oldest record of the genus outside of Africa is Elephas planifrons which is known from the Late Pliocene of the Indian subcontinent, around 3.6 million years ago.^[6] However, the placement of Elephas planifrons within the genus has also been questioned.^[7] The earliest fossils of the ancestor of the modern Asian elephant, Elephas hysudricus date to the beginning of the Pleistocene, around 2.6 million years ago, with remains found on the Indian subcontinent.^[8] Modern Asian elephants had evolved from E. hysrudicus by the Late Pleistocene.^[9]

Taxonomy

The scientific name Elephas was proposed by Carl Linnaeus in 1758 who described the genus and an elephant from Ceylon.^[10] The genus is assigned to the proboscidean family Elephantidae and is made up of one living and seven extinct species:^[11]

• Elephas maximus – Asian elephant^[1]
  • Elephas maximus indicus – Indian elephant
  • Elephas maximus maximus – Sri Lankan elephant
  • Elephas maximus sumatranus – Sumatran elephant
  • Elephas maximus borneensis – Borneo elephant, proposed but not yet recognized as valid^[12]

The following Asian elephants were proposed as extinct subspecies, but are now considered synonymous with the Indian elephant:^[1]

• Elephas maximus sondaicus – Javan elephant †
• Elephas maximus rubridens – Chinese elephant †
• Elephas maximus asurus – Syrian elephant †

The following Elephas species are extinct:

• Elephas beyeri – dwarf elephant species described from fossil remains found in 1911 in Luzon, the Philippines by von Königswald^[13]
• Elephas ekorensis – described from the Kubi Algi Formation, Turkana, Kenya,^[11] dating to the Early Pliocene, one of the oldest species of the genus.^[14]
• Elephas hysudricus – described from fossil remains found in the Siwalik hills by Falconer and Cautley, 1845,^[15] thought to be the ancestor of the living Asian elephant.^[16]
• Elephas hysudrindicus – a fossil elephant of the Pleistocene of Java and different from Elephas maximus sondaicus^[17]
• Elephas planifrons - one of the oldest species, known from the Late Pliocene-Early Pleistocene of the Indian subcontinent.^[18]
• Elephas platycephalus a species sometimes recognised from the Pleistocene of India
• Elephas kiangnanensis a species sometimes recognised from the Early-Middle Pleistocene of China.^[19][20]
• Elephas atavus? known from the Early Pleistocene of Africa, traditionally considered part of Elephas/Palaeoloxodon recki

While formerly assigned to this genus, Elephas recki, the straight-tusked elephant E. antiquus and the dwarf elephants E. falconeri and E. cypriotes are now placed in the separate genus Palaeoloxodon, which is more closely related to African elephants.^[21] However, some material historically assigned to Elephas recki , such as Elephas recki atavus, may be closely related to true Elephas, rather than to Palaeoloxodon^[22] "Elephas" celebensis is now placed in Stegoloxodon.^[23]

References