Surameryx | |
---|---|
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Artiodactyla |
Family: | † Dromomerycidae |
Tribe: | † Aletomerycini |
Genus: | † Surameryx Prothero et al., 2014 |
Type species | |
†Surameryx acrensis Prothero et al., 2014 |
Surameryx is an extinct genus of herbivorous artiodactyls originally described as belonging to the extinct family Palaeomerycidae. A single species, S. acrensis, was described from the Late Miocene (between the Mayoan and Huayquerian SALMA, between 11.6 to 5.3 million years ago) of the Madre de Dios Formation, South America. [1] It was originally interpreted as one of the few northern mammals that entered South America before the Pliocene. [2] However, both its identification as a member of the family Palaeomerycidae and claims about its Miocene age were subsequently challenged. [3]
Surameryx is known from the left half of the nearly complete lower jaw, reminiscent of the North American palaeomerycids, which are known from numerous fossils. [2]
The jaw of Surameryx is similar to that of Barbouromeryx in having a premolar row without reduction compared to the molar row; additionally it showed the characteristic " Palaeomeryx fold", a typical molar crest present in various types of primitive ruminants, and a vertical groove on the back or inner surface of the fourth premolar. Surameryx still differs from its relatives in the much wider shape of the molars and premolars, and in its shorter, upward recurved coronoid process; the stylids were also higher than in other related genera. [2]
Surameryx acrensis was first named and described in 2014, based on the fossil jaw discovered in the Madre de Dios Formation extending along the Acre River in the area between Cobija, Bolivia and Assis Brasil. Surameryx is a representative of the palaeomerycids, an extinct family of Miocene artiodactyls related to cervids and giraffids. More specifically, Surameryx was a member of the dromomerycines, a group of palaeomerycids endemic to North America; within these, it seems to have a close relationship with Barbouromeryx trigonocorneus, a primitive dromomerycine of the middle Miocene (20–16 million years ago). [2] The name Surameryx is derived from the Spanish word sur ("south") and the Greek meryx ("ruminant"); the species name acrensis refers to the Acre River. [2]
If confirmed, the discovery of a dromomerycine in South America would be exceptional; until 2014 there were only sporadic findings of placental mammals other than xenarthrans or meridiungulates in South America in layers earlier than the Pliocene epoch. While the Great American Biotic Interchange is traditionally regarded as an event of the late Pliocene (about 3 million years ago), it actually started much earlier, going back at least to the late Miocene, about 10 million years ago. [2] The presence of Surameryx in the Amazon basin is evidence of this exchange in the Miocene, which had already been suggested by the presence of contemporary specimens of gomphotheriids ( Amahuacatherium ), [4] [5] peccaries ( Sylvochoerus and Waldochoerus ) and tapirs [6] and presence around the same time of ground sloths in North America ( Thinobadistes and Pliometanastes ). [7] It seems that the paleomerycids were unable to successfully colonize South America, while other groups fared better there. Proboscideans survived until the arrival of humans [8] ) and peccaries and tapirs currently live in South America. [2] However, the dating of the putative Miocene fossil beds in western Amazonia and the identification of the gomphothere remains as Amahuacatherium have been challenged. [9] [10] [11] [12]
Gasparini et al. (2021) reevaluated the fossil material of S. acrensis, and argued that dental characters used to assign this species to Dromomerycinae by Prothero et al. (2014) are not diagnostic, and can be also found in other groups of even-toed ungulates, including South American deers. The authors also noted that the teeth of the holotype specimen of S. acrensis are very worn and the heavy wear has played a part in confounding and obscuring some of the dental features. In addition, Gasparini et al. considered the provenance and age of known fossil material of S. acrensis to be dubious. The authors believed that the original interpretation of the holotype specimen of S. acrensis as a dromomerycine was heavily influenced by its supposed Miocene age. According to Gasparini et al., if the preserved morphology of the holotype specimen of S. acrensis is the only information considered, it is best interpreted as fossil material of a deer of uncertain specific identity, likely an old individual with a dental age greater than seven years. The authors considered it more likely that this specimen was of Quaternary rather than Miocene age. [3]
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.
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.
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 as part of the Great American Interchange. Gomphotheres are a paraphyletic group ancestral to Elephantidae, which contains modern elephants, as well as Stegodontidae.
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.
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.
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.
Solimoea acrensis is a prehistoric ateline monkey from the Late Miocene Solimões Formation of Brazil. It is the only known species of the genus Solimoea.
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.
Sinomammut is a mammutid proboscidean from the Miocene of China. Only one species, S. tobieni, is known, named in 2016.
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 to 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.
Prosthennops is a genus of extinct peccaries that lived in North and Central America between the middle Miocene and lower Pliocene.
"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 and largest known land mammals.
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