''Tetralophodon'' ("four-ridged tooth") is an extinct genus of "tetralophodont

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 ...

" belonging to the superfamily

Elephantoidea Elephantimorpha is a clade of proboscideans that contains the Mammutidae (mastodons), as well as Elephantida ( amebelodonts, choerolophodonts, gomphotheres, stegodontids and elephantids). All members of Elephantimorpha have the horizontal tooth r ...

, known from 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 ...

Afro-Eurasia Afro-Eurasia (also Afroeurasia and Eurafrasia) is a landmass comprising the continents of Africa, Asia, and Europe. The terms are compound (linguistics), compound words of the names of its constituent parts. Afro-Eurasia has also been called th ...

Taxonomy and evolution

The genus ''Tetralophodon'' (meaning "four-ridged tooth") was named in the mid-19th century with the discovery of the specialized teeth. ''Tetralophodon'' is suggested to have descended from the "trilophodont gomphothere" ''

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 ...

.'' "Tetralophodont gomphotheres" like ''Tetralophodon'' are thought to be ancestral to elephantids and

stegodontids Stegodontidae is an extinct family of proboscideans from Africa and Asia (with a single occurrence in Europe) from the Early Miocene (at least 17.3 million years ago) to the Late Pleistocene. It contains two genera, the earlier ''Stegolophodon' ...

,'''' with African species of ''Tetralophodon'' suggested to be the ancestor of elephantids. ''Tetralophodon'' is also suggested to be the ancestor of the fellow "tetralophodont gomphothere" ''

Anancus ''Anancus'' is an extinct genus of "tetralophodont gomphothere" native to Afro-Eurasia, that lived from the Tortonian stage of the late Miocene until its extinction during the Early Pleistocene, roughly from 8.5–2 million years ago. Taxonomy ...

''.

Description

A large individual of the European species ''T. longirostris'' is suggested to have been tall at the shoulder and up to 10 tonnes in weight. The first and second molar teeth are tetralophodont (bearing four pairs of cusps).van der Made, J
The Evolution of the Elephants and Their Relatives in the Context of Changing Climate and Geography
In ''Elefantentreich—Eine Fossilwelt in Europa''; Verlag Beier & Beran: Langenweißbach, Germany, 2010; pp. 340–360. ISBN 978-3-939414-48-3. The

mandibular symphysis In human anatomy, the facial skeleton of the skull the external surface of the mandible is marked in the median line by a faint ridge, indicating the mandibular symphysis (Latin: ''symphysis menti'') or line of junction where the two lateral ha ...

of the lower jaw is typically elongate and bears lower tusks. The lower tusks vary greatly in size and morphology between species, with some species having flattened tusks with an oval-shaped cross section, while others have tusks which are pyriform (pear-shaped) in cross section. The upper tusks are proportionally large, and lack enamel bands.

Distribution

These animals were very widespread and successful

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 ...

ns. Their fossils have been found from the Middle Miocene to the Late Miocene epochs of

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

Asia Asia ( , ) is the largest continent in the world by both land area and population. It covers an area of more than 44 million square kilometres, about 30% of Earth's total land area and 8% of Earth's total surface area. The continent, which ...

, and

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

. The likely oldest species in the genus, the European ''T. longirostris'' first appeared around 13–12.5 million years ago. The North American species, ''T. campester'' and ''T. fricki'', were moved to the genus ''

Pediolophodon ''Pediolophodon'' is an extinct gomphotheriid proboscidean genus from the middle to late Miocene of North America (Nebraska and Texas). ''Pediolophodon'' was a close relative of elephants (members of the Elephantinae subfamily of Elephantidae) ...

'' in 2007, which is suggested to be unrelated to ''Tetralophodon,'' but instead representing

parallel evolution Parallel evolution is the similar development of a trait in distinct species that are not closely related, but share a similar original trait in response to similar evolutionary pressure.Zhang, J. and Kumar, S. 1997Detection of convergent and pa ...

Ecology

Specimens of ''Tetralophodon'' from the late Miocene of East Africa have been suggested to be browsers and mixed feeders based on

mesowear Mesowear is a method, used in different branches and fields of biology. This method can apply to both extant and extinct animals, according to the scope of the study. Mesowear is based on studying an animal's tooth wearing fingerprint. In brief, eac ...

analysis. Analysis of tooth wear suggest that these individuals had developed proal movement (back to front motion) in the lower jaws, akin to that used by modern elephants, but different from that used by earlier gomphotheres.

References

{{Taxonbar, from=Q1955654 Gomphotheres Elephantoidea Prehistoric placental genera Pliocene proboscideans Miocene proboscideans Miocene mammals of Europe Miocene mammals of Asia Pliocene mammals of Europe Pliocene mammals of Asia Miocene mammals of Africa Pliocene mammals of Africa Fossil taxa described in 1857