''Rhynchotherium'' is an extinct genus of

proboscidea Proboscidea (; , ) is a taxonomic order of afrotherian mammals containing one living family (Elephantidae) and several extinct families. First described by J. Illiger in 1811, it encompasses the elephants and their close relatives. Three l ...

endemic to

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

and

Central America Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...

during the

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

through

Pliocene The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58Ma, living for approximately . This

gomphothere Gomphotheres are an extinct group of proboscideans related to modern elephants. First appearing in Africa during the Oligocene, they dispersed into Eurasia and North America during the Miocene and arrived in South America during the Pleistocene a ...

had two

tusk Tusks are elongated, continuously growing front teeth that protrude well beyond the mouth of certain mammal species. They are most commonly canine tooth, canine teeth, as with Narwhal, narwhals, chevrotains, musk deer, water deer, muntjac, pigs, ...

s and may have evolved from ''

Gomphotherium ''Gomphotherium'' (; "nail beast" for its double set of straight tusks) is an extinct genus of gomphothere proboscidean from the Neogene of Eurasia, Africa and North America. It is the most diverse genus of gompothere, with over a dozen valid sp ...

''.

Taxonomy

''Rhynchotherium'' was first described in 1868 on the basis of a lower jaw from the Miocene of

Tlaxcala Tlaxcala, officially the Free and Sovereign State of Tlaxcala, is one of the 32 federal entities that comprise the Political divisions of Mexico, Federal Entities of Mexico. It is divided into Municipalities of Tlaxcala, 60 municipalities and t ...

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

. Later, the type species epithet ''R. tlascalae'' was erected for the jaw by

Henry Fairfield Osborn Henry Fairfield Osborn, Sr. (August 8, 1857 – November 6, 1935) was an American paleontologist, geologist and eugenics advocate. He was professor of anatomy at Columbia University, president of the American Museum of Natural History for 25 y ...

in 1918. In 1921, a gomphothere skull from the Mt. Eden area of southern California was described as a subspecies of ''Trilophodon shepardi'' (a now-defunct combination for ''Mastodon shepardi''), ''T. s. edensis'', but was subsequently reassigned to ''Rhynchotherium''. Other species subsequently assigned to ''Rhynchotherium'' included ''R. falconeri'', ''R. paredensis'', ''R. browni'', and ''R. simpsoni''. It was the closest relative to ''

Cuvieronius ''Cuvieronius'' is an extinct New World genus of gomphothere which ranged from southern North America to western South America during the Pleistocene epoch. Reaching a shoulder height of and a body mass of , it was on average shorter but compara ...

'', and may be ancestral to it. Lucas and Morgan (2008) reviewed the taxonomy of ''Rhynchotherium'' and concluded that only ''R. edensis'', ''R. falconeri'', ''R. paredensis'', ''R. browni'', and ''R. simpsoni'' could be confidently referred to ''Rhynchotherium''. Because the genotype of ''Rhynchotherium'' is referable to ''Gomphotherium'', the ICZN was petitioned to conserve the genus by designating ''R. falconeri'' as the type species, which it did. Rhynchotherium falconeri

Misassigned species

* ''Mastodon shepardi'' Leidy, 1871 * ''Mastodon euhypodon'' Cope, 1884 - likely a species of ''

''LUCAS, S.G. & MORGAN, G.S., 2008. Taxonomy of Rhynchotherium (Mammalia, Proboscidea) from the Miocene-Pliocene of North America.- New Mex. Mus. Nat. Hist. Sci. Bull. 44: 71-87. * ''Tetrabelodon brevidens'' Cope, 1889 * ''Dibelodon praecursor'' Cope, 1893 * ''Rhynchotherium rectidens'' Osborn, 1923 * ''Aybelodon hondurensis'' Frick, 1933 * ''Blickotherium blicki'' Frick, 1933 * ''Rhynchotherium anguirivale'' Osborn, 1936 Phylogenetic position according to Mothé et al. (2016)

Life history

''Rhynchotherium'' appears to have travelled in large mixed-age herds. At least two ''Rhynchotherium'' death assemblages, dubbed " elephant graveyards", are known from opposite sides of the continent, in California and Florida. The Florida site contains 3,000 individual fossils representing 38 individuals, including at least one complete adult and seven complete juveniles. The site appears to represent an area where ''Rhynchotherium'' herds repeatedly became trapped and died, potentially around the curve of a river that they periodically crossed. Some individuals may have also been washed into the site from upstream.

References

{{Taxonbar, from=Q2353831 Gomphotheres Miocene proboscideans Pliocene proboscideans Neogene mammals of North America Prehistoric placental genera Fossil taxa described in 1868