| Named By: | Barbour and Sternberg in 1935 |
| Time Period: | Middle Miocene-Late Miocene |
| Location: | USA - Kansas & Texas |
| Size: | Unavailable |
| Diet: | Herbivore |
| Fossil(s): | Remains of at least two individuals |
| Classification: | | Chordata | Mammalia | Proboscidea | Gomphotheriidae | |
Gnathabelodon is an extinct proboscidean (elephant) genus endemic to North America that includes species that lived during the Middle to Late Miocene. They were called "spoon-billed mastodons" since their lower jaw was elongated and shaped like a shoe-horn or spoon. The genus Gnathabelodon consists of two species: Thorpe's spoon-billed mastodon (G. thorpei) and Buckner's spoon-billed mastodon (G. buckneri). The flaring of the tip of their lower jaw was similar to that of the "shovel-tuskers" (Platybelodon and Amebelodon); however, Gnathabelodon species are distinct in having no lower tusks whilst the "shovel tuskers" have broad, flattened lower tusks. The upper tusks are large and curve outwards and upwards. In respects to dentition and overall body form, it was similar to other species of Gomphotherium, but Mothe et al. (2016) recover Gnathabelodon as closer to brevirostrine gomphotheriids than to Gomphotherium.