| Tetralophodon Temporal range: | |
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| Mounted skeleton, Henan Geological Museum | |
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Proboscidea |
| Superfamily: | Elephantoidea |
| Genus: | † Tetralophodon Falconer, 1857 |
| Species | |
Tetralophodon ("four-ridged tooth") is an extinct genus of "tetralophodont gomphothere" belonging to the superfamily Elephantoidea, known from the Miocene of Afro-Eurasia. [2] [3] [4]
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. "Tetralophodont gomphotheres" like Tetralophodon are thought to be ancestral to elephantids and stegodontids, [5] with African species of Tetralophodon suggested to be the ancestor of elephantids. [6] Tetralophodon is also suggested to be the ancestor of the fellow "tetralophodont gomphothere" Anancus . [7]
A large individual of the European species T. longirostris is suggested to have been 3.45 metres (11.3 ft) tall at the shoulder and up to 10 tonnes in weight. [8] The first and second molar teeth are tetralophodont (bearing four pairs of cusps). [9] The mandibular symphysis 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. [10] [11] The upper tusks are proportionally large, [9] and lack enamel bands. [11]
These animals were very widespread and successful proboscideans. Their fossils have been found from the Middle Miocene to the Late Miocene epochs of Europe, Asia, and Africa. [9] The likely oldest species in the genus, the European T. longirostris first appeared around 13–12.5 million years ago. [12] The North American species, T. campester and T. fricki, were moved to the genus Pediolophodon in 2007, which is suggested to be unrelated to Tetralophodon, but instead representing parallel evolution. [13]
Specimens of Tetralophodon from the late Miocene of East Africa have been suggested to be browsers and mixed feeders based on mesowear 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. [14]
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. Proboscideans include some of the largest known land mammals. The largest land mammal of all time may have been a proboscidean; the elephant Palaeoloxodon namadicus has been estimated to be up to 5.2 m (17.1 ft) at the shoulder and may have weighed up to 22 t, surpassing the paraceratheres, the otherwise largest known land mammals, though this estimate was made based on a single fragmentary femur and is speculative. The largest extant proboscidean is the African bush elephant, with a record of size of 4 m (13.1 ft) at the shoulder and 10.4 t. In addition to their enormous size, later proboscideans are distinguished by tusks and long, muscular trunks, which were less developed or absent in early proboscideans.
A mastodon is a member of the genus Mammut, which strictly defined, was endemic to North America and lived from the late Miocene to the early Holocene. Mastodons belong to the order Proboscidea, the same order as elephants and mammoths. Mammut is the type genus of the extinct family Mammutidae, which diverged from the ancestors of modern elephants at least 27-25 million years ago, during the Oligocene.
Elephantidae is a family of large, herbivorous proboscidean mammals collectively called elephants and mammoths. These are large terrestrial mammals with a snout modified into a trunk and teeth modified into tusks. Most genera and species in the family are extinct. Only two genera, Loxodonta and Elephas, are living.
Mammutidae is an extinct family of proboscideans belonging to Elephantimorpha. It is best known for the mastodons, which inhabited North America from the Late Miocene until their extinction at beginning of the Holocene, around 11,000 years ago. The earliest fossils of the group are known from the Late Oligocene of Africa, around 24 million years ago, and fossils of the group have also been found across Eurasia. The name "mastodon" derives from Greek, μαστός "nipple" and ὀδούς "tooth", referring to their characteristic teeth.
Amebelodon is a genus of extinct proboscidean belonging to Amebelodontidae. The most striking attribute of this animal is its lower tusks, which are narrow, elongated, and distinctly flattened with the degree of flattening varying among the different species. One valid species is known for this genus, which was endemic to North America. Other species once assigned to Amebelodon are now assigned to the genus Konobelodon, which was once a subgenus.
Gomphotheres are an extinct group of proboscideans related to modern elephants. They were widespread across Afro-Eurasia and North America during the Miocene and Pliocene epochs and dispersed into South America during the Pleistocene as part of the Great American Interchange. Gomphotheres are a paraphyletic group that is ancestral to Elephantidae, which contains modern elephants, as well as Stegodontidae. While most famous forms such as Gomphotherium had long lower jaws with tusks, which is the ancestral condition for the group, some later members developed shortened (brevirostrine) lower jaws with either vestigial or no lower tusks, looking very similar to modern elephants, an example of parallel evolution, which outlasted the long-jawed gomphotheres. By the end of the Early Pleistocene, gomphotheres became extinct in Afro-Eurasia, with the last two genera, Cuvieronius ranging from southern North America to western South America, and Notiomastodon having a wide range over most of South America until the end of the Pleistocene around 12,000 years ago, when they became extinct following the arrival of humans.
Gomphotherium is an extinct genus of gomphothere proboscidean from the Neogene of Eurasia, Africa and North America. The genus is probably paraphyletic.
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.
Sinomastodon is an extinct gomphothere genus known from the Late Miocene to Early Pleistocene of Asia, including China, Japan, Thailand, Myanmar, Indonesia and probably Kashmir.
Stegotetrabelodon is an extinct genus of primitive elephantid from the Late Miocene to Early Pliocene of Africa, the Arabian Peninsula, and Italy.
Primelephas is a genus of Elephantinae that existed during the Miocene and Pliocene epochs. The name of the genus suggests 'first elephant'. These primitive elephantids are thought to be the common ancestor of Mammuthus, the mammoths, and the closely allied genera Elephas and Loxodonta, the Asian and African elephants, diverging some 4-6 million years ago. It had four tusks, which is a trait not shared with its descendants, but common in earlier proboscideans. The type species, Primelephas gomphotheroides, was described by Vincent Maglio in 1970, with the specific epithet indicating the fossil specimens were gomphothere-like. Primelephas korotorensis is the only other species to be assigned to the genus. All fossils found of the Primelephas have been found in Africa, primarily in modern day Chad, Tanzania, Kenya, Ethiopia, and Uganda.
Rhynchotherium is an extinct genus of proboscidea endemic to North America and Central America during the Miocene through Pliocene from 13.650 to 3.6 Ma, living for approximately 10 million years.
Paratetralophodon is an extinct genus of proboscidean from late Neogene deposits in India and China. Although traditionally classified in the family Gomphotheriidae, recent studies find it to be more closely related to modern elephants.
Eubelodon is an extinct genus of gomphothere which lived in North America during the Miocene Epoch. It contains a single species: Eubelodon morrilli.
Stegodontidae is an extinct family of proboscideans from Africa and Asia from the Early Miocene to the Late Pleistocene. It contains two genera, the earlier Stegolophodon, known from the Miocene of Asia and the later Stegodon, from the Late Miocene to Late Pleistocene of Africa and Asia which is thought to have evolved from the former. The group is noted for their plate-like lophs on their teeth, which are similar to elephants and different from those of other extinct proboscideans like gomphotheres and mammutids, with both groups having a proal jaw movement utilizing forward strokes of the lower jaw. These similarities with modern elephants were probably convergently evolved. Like elephantids, stegodontids are thought to have evolved from gomphothere ancestors.
Choerolophodon is an extinct genus of proboscidean that lived during the Miocene of Eurasia and Africa. Fossils of Choerolophodon have been found in Africa, Southeast Europe, Turkey, Iraq, Iran, the Indian subcontinent, and China.
Konobelodon is an extinct genus of amebelodont proboscidean from the Miocene of Africa, Eurasia and North America.
Amebelodontidae is an extinct family of large herbivorous proboscidean mammals related to elephants. They were formerly assigned to Gomphotheriidae, but recent authors consider them a distinct family. They are distinguished from other proboscideans by having flattened lower tusks and very elongate mandibular symphysis. The lower tusks could grow considerable size, with those of Konobelodon reaching 1.61 metres (5.3 ft) in length. Their molar teeth are typically trilophodont, and possessed posttrite conules. In the past, amebelodonts' shovel-like mandibular tusks led to them being portrayed scooping up water plants, however, dental microwear suggests that they were browsers and mixed feeders. The lower tusks have been proposed to have had a variety of functions depending on the species, including stripping bark, cutting through vegetation, as well as possibly digging. They first appeared in Africa during the Early Miocene, and subsequently dispersed into Eurasia and then North America. They became extinct by the beginning of the Pliocene. While some phylogenetic studies have recovered Amebelodontidae as a monophyletic group that forms the sister group to Gomphotheriidae proper, some authors have argued that Amebelodontidae may be polyphyletic, with it being suggested that the shovel-tusked condition arose several times independently within Gomphotheriidae, thus rendering the family invalid.
Protanancus is an extinct genus of amebelodontid proboscidean from Kenya, Pakistan and Thailand. The genus consists solely of type species P. macinnesi. The generic name is derived from the unrelated Anancus, and the Greek prōtos "first".
The research history of Mammut is extensive given its complicated taxonomic and non-taxonomic histories, with the earliest recorded fossil finds dating back to 1705 in Claverack, New York during the colonial era of what is now the United States of America. Initially thought to belong to biblical antediluvian giants, the fossils were later determined to belong to a proboscidean species as a result of more complete 18th century finds from the locality of Big Bone Lick in what is now Kentucky. The molars were studied by European and American naturalists, who were generally baffled on its lack of analogue to modern elephants, leading to varying hypothesis on the affinities of the teeth. More complete skeletons were found after the independence of the United States colonies from Great Britain within the early 19th century. American historians of the 21st century have made arguments that the early history of M. americanum finds and studies played major roles in shaping American nationalism on the basis of the large sizes and relative completeness of the fossils to disprove the negative theory of social degeneracy in North America.
Genera of the order Proboscidea | ||||||||||||||||||||||||||||||
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