Gomphotherium (/ˌɡɒmfəˈθɪəriəm/; "nail beast" for its double set of straight tusks) is an extinct genus ofgomphothereproboscidean from theNeogene 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 probablyparaphyletic.[3][4]
Skeletal restoration ofG. productum (right) andG. steinheimense (left) compared to a human
Most species ofGomphotherium were similar in size to theAsian elephant, withG. 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 speciesG. steinheimense, known from a complete 37-year-old male found inMühldorf, 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 basalelephantimorphs, had an elongated lower jaw which bore tusks.[6] Species ofGomphotherium 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]
Most species ofGomphotherium are inferred to have beenbrowsers or mixed feeders, but specimens ofG.steinheimense from China are suggested to have beengrazers.[3] Oxygen and carbon isotopes fromG. productum enamel unearthed in the Port of Entry Pit, Oklahoma reveal it fed predominantly onC3 plants year-round.[8]
Gomphotherium likely originated in Africa during the lateOligocene-earlyMiocene. The oldest remains ofGomphotherium 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 beparaphyletic and the ancestor of later gomphothere genera, including the "tetralophodont gomphotheres" such asTetralophodon which are probably ancestral tostegodontids andelephantids.[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 asCuvieronius,Stegomastodon andRhynchotherium.[12] Asian populations ofGomphotherium are suggested to have been ancestral toSinomastodon.[13] The last European species ofGomphotherium became extinct at the beginning of the Late Miocene, around the start ofMN9, approximately 10 million years ago.[13] The lastGomphotherium species disappeared from North America at the beginning of the Pliocene, approximately 5 million years ago.[11]
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