Zygolophodon Temporal range: | |
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Skull of Zygolophodon sp. from Laogou, Gansu Province, China | |
Molars of Zygolophodon turicensis | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Proboscidea |
Family: | † Mammutidae |
Genus: | † Zygolophodon Vacek, 1877 |
Type species | |
†Mastodon turicensis Schinz, 1824 | |
Species | |
Possibly valid species:
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Synonyms | |
List
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Zygolophodon is an extinct genus of mammutid proboscidean that lived during the Miocene in Africa, Eurasia, and North America. [1]
As with other mammutids, the molars have a zygodont morphology. The lower jaw has an elongate mandibular symphysis and bears tusks/incisors. [2] [3] The upper tusks have enamel bands and are untwisted and downward curving, and outwardly diverge from each other. [4] The jaws retained permanent premolar teeth. [5]
Zygolophodon is suggested to have primarily had a browsing-based diet. [6]
Zygolophodon belongs in the family Mammutidae, whose best known member is the American mastodon (Mammut americanum).
The genus likely originated in Africa. The oldest species is Z. aegyptensis, known from Egypt and Namibia, dating to the late Early Miocene-early Middle Miocene. [7] [8] The species Z. turicensis had a widespread distribution in both Africa (Kenya, Tunisia), Anatolia and Europe, dating to the Early-Late Miocene, [9] [8] with its earliest appearance in Europe being approximately 18-17 million years ago, [10] and last appearance in the region dating to around 7-6 million years ago. [11] The youngest confirmed record of Zygolophodon in Africa dates to around 13 million years ago, based on teeth suggested to belong to Z. turicensis found in Kenya, though a possible younger record is known from the Late Miocene of Algeria. [12]
The species Z. tapiroides (Desmarets, 1822) is considered invalid. [8] [13] The taxonomy of East Asian Zygolophodon is uncertain. Tassy et al. (1988) synonymised many Chinese species with Z. gobiensis (including Z. lufengensis, Z. chinjiensis, Z. nemonguensis, Z. gromovae and Z. jiningensis, as well as Miomastodon tongxiensis), with Z. gobiensis also known from Mongolia, but other authors suggest that at least some of these species may be valid. [8] The species Z. atavus is known from the early Middle Miocene of Kazakhstan. [8] The oldest remains of Zygolophodon on the Indian subcontinent are known from the Bugti Hills of Pakistan, dating to around 19-17 million years ago. The species Z. metachinjiensis is known from the mid-Late Miocene of Pakistan. [14] Zygolophodon has also been reported from western India, dating to the mid Miocene, [15] and other probable remains dating to the Late Miocene, around 10 million years old, representing the youngest mammutids on the Indian subcontinent. [14] An indeterminate species has also been reported from Thailand, of uncertain but probably Late Miocene age. [8]
Zygolophodon entered North America during the latter part of the Early Miocene (during the late Hemingfordian faunal stage), with the oldest record being a partial tooth from Massacre Lake, Nevada, dating to 16.5-16.4 million years ago. [3] Remains of Zygolophodon are known from across western and central North America during the following Barstovian (including Colorado, California, Montana, Oregon, Nebraska, Nevada, Wyoming and Saskatchewan). Z. proavus currently represents the only known North American species of Zygolophodon. [13] [3] The youngest specimens of Z. proavus date to approximately 11-12 million years ago. [3] Mammut is thought to be descended from Zygolophodon. The species "Mammut" borsoni, whose relationship with North American Mammut is controversial, and sometimes placed in Zygolophodon (from which, like North American Mammut, it descended from), is the youngest member of Mammutidae in Eurasia, persisting from the Late Miocene into the Earliest Pleistocene, around 2.5-2 million years ago. [10]
Some authors have suggested placing M. tongxinensis, Z.gobiensis and Z. metachinjiensis within a revived Miomastodon, which was originally described for the North American Miomastodon merriami. [16] Miomastodon is usually treated as a synonym of Zygolophodon (with M. merriami typically considered a synonym of Z. proavus) [13] and other authors have reacted with caution to the proposal. [10]
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 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.
Stegomastodon is an extinct genus of gomphotheres, a family of proboscideans. It ranged throughout North America from the early Blancan ~4 Ma, to the early Irvingtonian. The 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.
Archaeobelodon is an extinct genus of proboscidean of the family Amebelodontidae that lived in Europe and North Africa (Egypt) during the Miocene from 16.9 to 16.0 Ma, living for approximately 0.9 million years.
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.
Sinomammut is a mammutid proboscidean from the Miocene of China. Only one species, S. tobieni, is known, named in 2016.
Eozygodon is an extinct genus of proboscidean in the family Mammutidae that is based on a single species, E. morotoensis, named in 1983. It is known from the Early Miocene of Africa and well as possibly the Middle Miocene of China. It is considered a primitive member of the family, retaining a long lower jaw (longirostrine) with lower tusks. The upper tusks are small and are parallel to each other. The body mass is considerably smaller than the American mastodon. Dental mesowear from East African specimens suggests a browsing diet.
Eurybelodon is an extinct genus of proboscidean in the family Amebelodontidae. It lived in the Clarendonian age of the Miocene.
"Mammut" borsoni is an extinct species of mammutid proboscidean known from the Late Miocene to Early Pleistocene of Eurasia, spanning from western Europe to China. It is the last known mammutid in Eurasia, and amongst the largest of all proboscideans.
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.
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