Gomphotherium (/ˌɡɒmfəˈθɪəriəm/; "nail beast" for its double set of straight tusks) is an extinct genus of
gomphothereproboscidean from the
Neogene of Eurasia, Africa and North America.[1][2] It is the most diverse genus of gompothere, with over a dozen valid species. The genus is probably
paraphyletic.[3][4]
Description
Skeletal restoration of G. productum (right) and G. steinheimense (left) compared to a human
Most species of Gomphotherium were similar in size to the
Asian elephant, with G. productum (known from a 35-year-old male) measuring 2.51 m (8 ft 3 in) tall and weighing 4.6 t (4.5 long tons; 5.1 short tons). The largest species G. steinheimense, known from a complete 37-year-old male found in
Mühldorf, Germany, measured up to 3.17 m (10.4 ft) tall and weighed 6.7 t (6.6 long tons; 7.4 short tons).[5]
Gomphotherium, like most basal
elephantimorphs, had an elongated lower jaw which bore tusks.[6] Species of Gomphotherium are defined by their conservative molar morphology, which includes "trilophed intermediate molars, third molars with three to four loph(id)s, and pretrite half-loph(id)s typically with anterior and posterior accessory conules that form trefoil-patterned enamel loops with wear (simple molar crowns with no accessory conules on the posttrite side of the crown)".[7]
Ecology
Most species of Gomphotherium are inferred to have been
browsers or mixed feeders, but specimens of G. steinheimense from China are suggested to have been
grazers.[3] Oxygen and carbon isotopes from G. productum enamel unearthed in the Port of Entry Pit, Oklahoma reveal it fed predominantly on
C3 plants year-round.[8]
Evolution
Gomphotherium likely originated in Africa during the late
Oligocene-early
Miocene. The oldest remains of Gomphotherium are known from Africa, dating to approximately 19.5 million years ago.[9] Gomphotherium migrated into Eurasia across the "
Gomphotherium land bridge" approximately 19 million years ago.[10]Gomphotherium underwent rapid evolution after its arrival in Eurasia, reaching its peak diversity during the Early-Middle Miocene.[10]Gomphotherium has been posited to be
paraphyletic and the ancestor of later gomphothere genera, including the "tetralophodont gomphotheres" such as Tetralophodon which are probably ancestral to
stegodontids and
elephantids.[3]Gomphotherium first arrived in North America during the mid-Miocene, approximately 16-15 million years ago,[11] and is suggested to be ancestral to later New World gomphothere genera, such as Cuvieronius, Stegomastodon and Rhynchotherium.[12] Asian populations of Gomphotherium are suggested to have been ancestral to Sinomastodon.[13] The last European species of Gomphotherium became extinct at the beginning of the Late Miocene, around the start of
MN9, approximately 10 million years ago.[13] The last Gomphotherium species disappeared from North America at the beginning of the Pliocene, approximately 5 million years ago.[11]