- Largely unworn molar of Gomphotherium angustidens , a "trilophodont gomphothere"
- Worn molar of Gomphotherium angustidens
- Molar of Tetralophodon , a "tetralophodont gomphothere "
- Molar of a modern African elephant ( Loxodonta ) for comparison
Gomphothere Temporal range: Late Oligocene - Holocene | |
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Specimen of Gomphotherium productum at the American Museum of Natural History | |
Notiomastodon platensis Centro Cultural del Bicentenario de Santiago del Estero in Argentina | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Proboscidea |
Superfamily: | † Gomphotherioidea |
Family: | † Gomphotheriidae (Hay, 1922) A. Cabrera 1929 |
Genera | |
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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.
The name "gomphothere" comes from Ancient Greek γόμφος (gómphos), "peg, pin; wedge; joint" plus θηρίον (theríon), "beast".
Gomphotheres differed from elephants in their tooth structure, particularly the chewing surfaces on the molar teeth. The teeth are considered to be bunodont, that is, having rounded cusps. [1] They are thought to have chewed differently from modern elephants, using an oblique movement (combining back to front and side to side motion) over the teeth rather than the proal movement (a forwards stroke from the back to the front of the lower jaws) used by modern elephants and stegodontids. [2] Like modern elephants and other members of Elephantimorpha, gomphotheres had horizontal tooth replacement, where teeth would progressively migrate towards the front of the jaws before they were taken the place of by more posterior teeth. Unlike modern elephants, many gomphotheres retained permanent premolar teeth [3] though they were absent in some gomphothere genera. [4] Earlier gomphotheres had lower jaws with an elongate mandibular symphysis and lower tusks, the primitive condition for members of Elephantimorpha. Later members developed shortened (brevirostrine) lower jaws and/or vestigial or no lower tusks, a convergent process that occurred multiple times among gomphotheres, as well as other members of Elephantimorpha. [4] The incisors and long lower jaws of primitive gomphotheres were likely used for cutting vegetation, while brevirostrine gomphotheres relied on their trunks to acquire food similar to modern elephants. [5]
"Gomphotheres" are assigned to their own family, Gomphotheriidae, but are widely agreed to be a paraphyletic group. The families Choerolophodontidae and Amebelodontidae (the latter of which includes "shovel tuskers" with flattened lower tusks like Platybelodon ) are sometimes considered gomphotheres sensu lato, [6] [7] [8] though some authors argue that Amebelodontidae should be sunk into Gomphotheriidae. [9] Gomphotheres are divided into two informal groups, "trilophodont gomphotheres", and "tetralophodont gomphotheres". "Tetralophodont gomphotheres" are distinguished from "trilophodont gomphotheres" by the presence of four ridges on the fourth premolar and on the first and second molars, rather than the three present in trilophodont gomphotheres. [6] Some authors choose to exclude "tetralophodont gomphotheres" from Gomphotheriidae, and instead assign them to the group Elephantoidea. [6] "Tetralophodont gomphotheres" are thought to have evolved from "trilophodont gomphotheres", and are suggested to be ancestral to Elephantidae, the group which contains modern elephants, as well as Stegodontidae. [10]
While the North American long jawed proboscideans Gnathabelodon, Eubelodon and Megabelodon been assigned to Gomphotheriidae in some studies [4] [11] other studies suggest that they should be assigned to Amebelodontidae (Eubelodon, Megabelodon) or Choerolophodontidae (Gnathabelodon). [5]
Cladogram of Elephantimorpha after Li et al. 2023, showing a paraphyletic Gomphotheriidae. [5]
Elephantimorpha |
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Gomphotheres are generally supposed to have been flexible feeders, with the various species having differing browsing, mixed feeding and grazing diets, with the dietary preference of individual species and populations being shaped by local factors such as climactic conditions and competition. [12] Analysis of the tusks of a male Notiomastodon individual suggest that it underwent musth, similar to modern elephants. [13] Notiomastiodon is also suggested to have lived in social family groups, like modern elephants. [14]
Gomphotheres originated in Afro-Arabia during the mid-Oligocene, with remains from the Shumaysi Formation in Saudi Arabia dating to around 29-28 million years ago. Gomphotheres were uncommon in Afro-Arabia during the Oligocene. [15] Gomphotheres arrived in Eurasia after the connection of Afro-Arabia and Eurasia during the Early Miocene around 19 million years ago, [16] in what is termed the "Proboscidean Datum Event". Gomphotherium arrived in North America around 16 million years ago, [17] and is suggested to be the ancestor of later New World gomphothere genera. [18] "Trilophodont gomphotheres" dramatically declined during the Late Miocene, likely due to the increasing C4 grass-dominated habitats, [16] while during the Late Miocene "tetralophodont gomphotheres" were abundant and widespread in Eurasia, where they represented the dominant group of proboscideans. [19] All trilophodont gomphotheres, with the exception of the Asian Sinomastodon , became extinct in Eurasia by the beginning of the Pliocene, [20] along with the global extinction of the "shovel tusker" amebelodontids. [21] The last gomphotheres in Africa, represented by the "tetralophodont gomphothere" genus Anancus , became extinct around the end of the Pliocene and beginning of the Pleistocene. [22] The New World gomphothere genera Notiomastodon and Cuvieronius dispersed into South America during the Pleistocene, around or after 2.5 million years ago as part of the Great American Biotic Interchange due to the formation of the Isthmus of Panama, becoming widespread across the continent. [23] The last gomphothere native to Europe, Anancus arvernensis [24] became extinct during the Early Pleistocene, around 1.6–2 million years ago [25] [26] Sinomastodon became extinct at the end of the Early Pleistocene, around 800,000 years ago. [27] From the latter half of the Early Pleistocene onwards, gomphotheres were extirpated from most of North America, likely due to competition with mammoths and mastodons. [28]
The extinction of gomphotheres in Afro-Eurasia has generally been supposed to be the result the expansion of Elephantidae and Stegodon. [20] [29] The morphology of elephantid molars being more efficient than gomphotheres in consuming grass, which became more abundant during the Pliocene and Pleistocene epochs. [29] In southern North America, Central America and South America, gomphotheres did not become extinct until shortly after the arrival of humans to the Americas, approximately 12,000 years ago, as part of the Late Pleistocene megafauna extinctions of most large mammals across the Americas. Bones of the last gomphothere genera, Cuvieronius and Notiomastodon, dating to shortly before their extinction have been found associated with human artifacts, suggesting that hunting may have played a role in their extinction. [23]
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 species of elephant are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant.
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.
Gomphotherium 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 species. 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.
Cuvieronius is an extinct New World genus of gomphothere which ranged from southern North America to western South America during the Pleistocene epoch. Among the last gomphotheres, it became extinct at the end of the Pleistocene, approximately 12,000 years ago, following the arrival of humans to the Americas.
Stegomastodon is an extinct genus of gomphotheres. It ranged throughout North America from the Pliocene, to the Early Pleistocene. The former South American species have been synonymized with Notiomastodon platensis.
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.
Tetralophodon is an extinct genus of "tetralophodont gomphothere" belonging to the superfamily Elephantoidea, known from the Miocene of Afro-Eurasia.
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.
Gnathabelodon is an extinct genus of gomphothere endemic to North America that includes species that lived during the Middle to Late Miocene.
Eubelodon is an extinct genus of gomphothere which lived in North America during the Miocene Epoch. It contains a single species: Eubelodon morrilli.
Notiomastodon is an extinct genus of gomphothere proboscidean, endemic to South America from the Pleistocene to the beginning of the Holocene. Notiomastodon specimens reached a size similar to that of the modern Asian elephant, with a body mass of 3-4 tonnes. Like other brevirostrine gomphotheres such as Cuvieronius and Stegomastodon, Notiomastodon had a shortened lower jaw and lacked lower tusks, unlike more primitive gomphotheres like Gomphotherium.
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.
Elephantimorpha is a clade of proboscideans that contains the Mammutidae (mastodons), as well as Elephantida. All members of this group have the horizontal tooth replacement typical of modern elephants, unlike more primitive members of the Elephantiformes. Like modern elephants, the ancestor of Elephantimorpha was likely capable of communicating via infrasonic calls. While early elephantimorphs generally had lower jaws with an elongated mandibular symphysis at the front of the jaw with well developed lower tusks/incisors, from the Late Miocene onwards, many groups convergently developed brevirostrine (shortened) lower jaws with vestigial or no lower tusks, corresponding with the elongation and increasingly dexterity of the trunk allowing it to be used as the primary feeding organ.
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.
Eurybelodon is an extinct genus of proboscidean in the family Amebelodontidae. It lived in the Clarendonian age of the Miocene.