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Ungulates are members of the diverse clade Euungulata, which primarily consists of large mammals with hooves. Once part of the clade "Ungulata" along with the clade Paenungulata, "Ungulata" has since been determined to be a polyphyletic and thereby invalid clade based on molecular data. As a result, true ungulates had since been reclassified to the newer clade Euungulata in 2001 within the clade Laurasiatheria while Paenungulata has been reclassified to a distant clade Afrotheria. Living ungulates are divided into two orders: Perissodactyla including equines, rhinoceroses, and tapirs; and Artiodactyla including cattle, antelope, pigs, giraffes, camels, sheep, deer, and hippopotamuses, among others. Cetaceans such as whales, dolphins, and porpoises are also classified as artiodactyls, although they do not have hooves. Most terrestrial ungulates use the hoofed tips of their toes to support their body weight while standing or moving. Two other orders of ungulates, Notoungulata and Litopterna, both native to South America, became extinct at the end of the Pleistocene, around 12,000 years ago.
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name molar derives from Latin, molaris dens, meaning "millstone tooth", from mola, millstone and dens, tooth. Molars show a great deal of diversity in size and shape across the mammal groups. The third molar of humans is sometimes vestigial.
Lavanify is a mammalian genus from the late Cretaceous of Madagascar. The only species, L. miolaka, is known from two isolated teeth, one of which is damaged. The teeth were collected in 1995–1996 and described in 1997. The animal is classified as a member of Gondwanatheria, an enigmatic extinct group with unclear phylogenetic relationships, and within Gondwanatheria as a member of the family Sudamericidae. Lavanify is most closely related to the Indian Bharattherium; the South American Sudamerica and Gondwanatherium are more distantly related. Gondwanatheres probably ate hard plant material.
Teleoceras is an extinct genus of rhinocerotid. It lived in North America during the Miocene and Pliocene epochs during the Hemingfordian to the end of Hemphillian from around 17.5 to 4.9 million years ago. It grew up to lengths of 13 feet long.
Gigantopithecus is an extinct genus of ape that lived in southern China from 2 million to approximately 300,000 to 200,000 years ago during the Early to Middle Pleistocene, represented by one species, Gigantopithecus blacki. Potential identifications have also been made in Thailand, Vietnam, and Indonesia. The first remains of Gigantopithecus, two third molar teeth, were identified in a drugstore by anthropologist Ralph von Koenigswald in 1935, who subsequently described the ape. In 1956, the first mandible and more than 1,000 teeth were found in Liucheng, and numerous more remains have since been found in at least 16 sites. Only teeth and four mandibles are known currently, and other skeletal elements were likely consumed by porcupines before they could fossilise. Gigantopithecus was once argued to be a hominin, a member of the human line, but it is now thought to be closely allied with orangutans, classified in the subfamily Ponginae.
Ferugliotheriidae is one of three known families in the order Gondwanatheria, an enigmatic group of extinct mammals. Gondwanatheres have been classified as a group of uncertain affinities or as members of Multituberculata, a major extinct mammalian order. The best-known representative of Ferugliotheriidae is the genus Ferugliotherium from the Late Cretaceous epoch in Argentina. A second genus, Trapalcotherium, is known from a single tooth, a first lower molariform, from a different Late Cretaceous Argentinean locality. Another genus known from a single tooth, Argentodites, was first described as an unrelated multituberculate, but later identified as possibly related to Ferugliotherium. Finally, a single tooth from the Paleogene of Peru, LACM 149371, perhaps a last upper molariform, and a recent specimen from Mexico, may represent related animals.
Toxodontia is a suborder of the meridiungulate order Notoungulata. Most of the members of the five included families, including the largest notoungulates, share several dental, auditory and tarsal specializations. The group is named after Toxodon, the first example of the group to be discovered by science.
Chilotherium is an extinct genus of rhinocerotids endemic to Eurasia during the Miocene through Pliocene living for 13.7—3.4 mya, existing for approximately 10.3 million years.
Hypohippus is an extinct genus of three-toed horse, which lived 17–11 million years ago. It was the largest anchitherine equid about the size of a modern domestic horse, at 403–600 kg (888–1,323 lb) and 1.8 m (5.9 ft) long. It was a long-necked, high-shouldered browser with sub-hypsodont, lophodont (rhino-like) dentition, that fed on the tough vegetation of forest understory and shrubs. Its deep preorbital fossae and retraction of the nasal notch hint at the presence of a long, muscular and prehensile upper lip that would aid during selective browsing. Overall its ecology would have been more comparable to modern okapi than to grazing horses. Fossils of it have been found in Nebraska, Colorado, and Montana.
Megahippus is an extinct genus of large Anchitheriine horses found throughout the southern portion of the United States during the middle Miocene. The animal represents one of the latest low-crowned horses, overlapping in time with more derived high-crowned horses.
Hemiauchenia is a genus of laminoid camelids that evolved in North America in the Miocene period about 10 million years ago. This genus diversified and entered South America in the Late Pliocene about three to two million years ago, as part of the Great American Biotic Interchange. The genus became extinct at the end of the Pleistocene. The monophyly of the genus has been considered questionable, with phylogenetic analyses finding the genus to paraphyletic or polyphyletic, with some species suggested to be more closely related to living lamines than to other Hemiauchenia species.
Aphelops is an extinct genus of hornless rhinocerotids endemic to North America. It lived from the Middle Miocene to the early Pliocene, during which it was a common component of North American mammalian faunas along with Teleoceras.
A tooth is a hard, calcified structure found in the jaws of many vertebrates and used to break down food. Some animals, particularly carnivores and omnivores, also use teeth to help with capturing or wounding prey, tearing food, for defensive purposes, to intimidate other animals often including their own, or to carry prey or their young. The roots of teeth are covered by gums. Teeth are not made of bone, but rather of multiple tissues of varying density and hardness that originate from the outermost embryonic germ layer, the ectoderm.
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, each animal has special feeding habits, which cause unique tooth wearing. Rough feeds cause serious tooth abrasion, while smooth one triggers moderate abrasion, so browsers have teeth with moderate abrasion and grazers have teeth with rough abrasion. Scoring systems can quantify tooth abrasion observations and ease comparisons between individuals.
Teeth are common to most vertebrates, but mammalian teeth are distinctive in having a variety of shapes and functions. This feature first arose among early therapsids during the Permian, and has continued to the present day. All therapsid groups with the exception of the mammals are now extinct, but each of these groups possessed different tooth patterns, which aids with the classification of fossils.
Bharattherium is a mammal that lived in India during the Maastrichtian and possibly the Paleocene. The genus has a single species, Bharattherium bonapartei. It is part of the gondwanathere family Sudamericidae, which is also found in Madagascar and South America during the latest Cretaceous. The first fossil of Bharattherium was discovered in 1989 and published in 1997, but the animal was not named until 2007, when two teams independently named the animal Bharattherium bonapartei and Dakshina jederi. The latter name is now a synonym. Bharattherium is known from a total of eight isolated fossil teeth, including one incisor and seven molariforms.
The grit, not grass hypothesis is an evolutionary hypothesis that explains the evolution of high-crowned teeth, particularly in New World mammals. The hypothesis is that the ingestion of gritty soil is the primary driver of hypsodont tooth development, not the silica-rich composition of grass, as was previously thought.
Patagonia is an extinct genus of non-placental mammal from the Miocene of Argentina. Traditionally considered a metatherian incertae sedis, one analysis suggested it to be a gondwanathere. However, this has been rejected by other authors.
Damaliscus hypsodon is an extinct species of antelope from the Middle-Late Pleistocene of Africa. Fossils have been found in Kenya and Tanzania.
Argyrohippus is an extinct genus of notoungulate, belonging to the family Notohippidae. It lived from the Late Oligocene to the Early Miocene, and its fossilized remains were found in South America.
References
- ↑ Parker, Abigail K.; McHorse, Brianna K.; Pierce, Stephanie E. (15 December 2018). "Niche modeling reveals lack of broad-scale habitat partitioning in extinct horses of North America". Palaeogeography, Palaeoclimatology, Palaeoecology . 511: 103–118. doi:10.1016/j.palaeo.2018.07.017 . Retrieved 2 January 2025– via Elsevier Science Direct.
- ↑ Phillip E. Jardine, Christine M. Janis, Sarda Sahney, Michael J. Benton. “Grit not grass: Concordant patterns of early origin of hypsodonty in Great Plains ungulates and Glires.” Palaeogeography, Palaeoclimatology, Palaeoecology. December 2012:365–366, 1–10
- ↑ Flynn, John J., André R. Wyss, and Reynaldo Charrier. “South America’s Missing Mammals.” Scientific American. May 2007: 68-75.
- ↑ Kwan, Paul W.L. (2007). "Digestive system I" (PDF). Tufts University. Archived from the original (PDF) on 20 October 2013. Retrieved 4 July 2019.
- ↑ Gondwanatheria