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Toxodonta
Toxodontia. Retrieved April 2013. 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. Description Isotemnidae, the oldest and most primitive family of toxodonts, were generally large animals with larger canines than other early notoungulates. The family is probably paraphyletic or polyphyletic since only primitive dental features unite the 12 included genera, such as a complete dentition with unreduced canines and no diastemata in the earliest genera. Likewise, they are only weakly linked to other toxodonts by a few dental features, and their primitive cheek tooth pattern can be basal to all notoungulates except notioprogonians. The oldest of the 12 genera in this family is ''Isotemnus'' known from the Riochican-Casamayoran, but ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Notoungulata
Notoungulata is an extinct order of mammalian ungulates that inhabited South America from the early Paleocene to the Holocene, living from approximately 61 million to 11,000 years ago. Notoungulates were morphologically diverse, with forms resembling animals as disparate as rabbits and rhinoceroses. Notoungulata are the largest group of South American native ungulates, with over 150 genera in 14 families having been described, divided into two major subgroupings, Typotheria and Toxodontia. Notoungulates first diversified during the Eocene. Their diversity declined during the Late Neogene, with only the large toxodontids persisting until the end of the Pleistocene. Collagen analysis suggests that notoungulates are closely related to litopterns, another group of South American ungulates, and their closest living relatives being perissodactyls (odd-toed ungulates), including rhinoceroses, tapirs and equines. but their relationships to other South American ungulates are uncertain. Se ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Isotemnus
''Isotemnus'' is an extinct genus of notoungulata, notoungulate belonging to the family Isotemnidae. It lived from the Late Paleocene to the Middle Eocene of what is now Argentina. Description This genus was smaller than ''Thomashuxleya'' and ''Periphragnis'', and did not exceed 50 kilograms in weight. Its build was comparable to a modern peccary, with a body relatively massive and strong and sturdy legs. Compared to other Eocene notoungulates, like basal Notohippidae and Notostylopidae, ''Isotemnus'' had an humerus whose distal part had a high medial trochlear crest, while the bicipital radial tuberosity was almost unexistant. The astragalus had a broad and low trochlea with a short neck. The calcaneus had rectangular fibular facets, and an unusually thick sustentaculum. Several of the distinctive anatomical leg characteristics of ''Isotemnus'' could be due to its smaller size ; ''Periphragnis'' and ''Thomashuxleya'', while very similar, had different characteristics. Classif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Notohippidae
Notohippidae is a paraphyly, paraphyletic extinct Family (biology), family of Notoungulata, notoungulate mammals from South America. Notohippids are known from the Eocene and Oligocene Epoch (reference date), epochs.McKenna, Malcolm C., and Bell, Susan K. 1997. ''Classification of Mammals Above the Species Level.'' Columbia University Press, New York, 631 pp. Description Although the name notohippids means "southern horses," these animals did not look like horses. The name refers to the teeth very similar to those of horses, with sharp incisors and high-crowned molars suitable for shredding grass. The shape of the skull and particularly the dentition is the result of convergent evolution with the equids, perissodactyl mammals that developed on the northern continents. The body of notohippids was rather stocky, supported by relatively elongated legs equipped with claws (and not hooves). The earliest forms of notohippids possessed low-crowned molars, but in the course of evoluti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deseadan
The Deseadan ( es, Deseadense) age is a period of geologic time (29.0–21.0 Ma) within the Oligocene epoch of the Paleogene to the Early Miocene epoch of the Neogene, used more specifically within the SALMA classification of South America. It follows the Tinguirirican and precedes the Colhuehuapian age. Etymology The age is named after the Deseado Formation of the Deseado Massif in eastern Patagonia, Argentina. Formations Fossils Correlations The Deseadan South American land mammal age (SALMA) is equivalent to the Arikareean in the North American land mammal age (NALMA) and the Harrisonian in the 2000 version of the classification. It overlaps with the Hsandagolian The Hsandagolian age is a period of geologic time (33.9 – 23.03 Ma) within the Oligocene epoch of the Paleogene used more specifically with Asian Land Mammal Ages. It follows the Kekeamuan and precedes the Tabenbulakian age. The Ulangochuian ... of Asia and the MP 25 zone of Europe, the Waitaki ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypsodont
Hypsodont is a pattern of dentition with high-crowned teeth and enamel extending past the gum line, providing extra material for wear and tear. Some examples of animals with hypsodont dentition are cows and horses; all animals that feed on gritty, fibrous material. The opposite condition is called brachydont. Evolution Since the morphology of the hypsodont tooth is suited to a more abrasive diet, hypsodonty was thought to have evolved concurrently with the spread of grasslands. Grass contains phytoliths, silica-rich granules, which wear away dental tissue more quickly. Analysis has shown however, that the development of this morphology is out of sync with the flourishing of grasslands. Instead, the ingestion of grit and soil is hypothesized to be the primary driver of hypsodonty (the Grit, not grass hypothesis). Morphology Hypsodont dentition is characterized by: * high-crowned teeth * A rough, flattish occlusal surface adapted for crushing and grinding * Cementum both above ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eomorphippus
''Eomorphippus'' is an extinct genus of notohippid notoungulate that lived from the Late Eocene to the Early Oligocene in what is today South America. Description This animal was approximately the size of a goat, with a build probably more robust. It had a heavy and sturdy skull, with a relatively short muzzle. The dentition was characterized by high-crowned (hypsodont) incisors, posterior premolars and molars. The teeth didn't have cementum. The upper incisors were slightly protruding forward. The third upper incisor was wider than the other two, while the fourth premolar was more molariform than the other premolars, but devoid of a distinct hypocone. The upper molars had hypocones, with a variable but generally deep fissure separating them from the protocones. The fissure was blocked by the medial projection of a hooked structure. Apart from the permanent major fossa, the other fossae are erased with wear. Classification The genus ''Eomorphippus'' was first described in 190 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mustersan
The Mustersan age is a period of geologic time (48.0–42.0 Ma) within the Eocene epoch of the Paleogene, used more specifically within the South American land mammal age (SALMA) classification. It follows the Casamayoran and precedes the Divisaderan age.Mustersan at .orgWoodburne et al., 2013 Etymology This age is named after Lake Musters in the |
Mixotoxodon
''Mixotoxodon'' ("mixture ''Toxodon''") is an extinct genus of notoungulate of the family Toxodontidae inhabiting South America, Central America and parts of southern North America during the Pleistocene epoch, from 1,800,000—12,000 years ago.''Mixotoxodon'' at .org Description 
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Rhynchippus
''Rhynchippus'' ("Snout Horse") is an extinct genus of notoungulate mammals from the Late Oligocene ( Deseadan in the SALMA classification) of South America. The genus was first described by Florentino Ameghino in 1897 and the type species is ''R. equinus'', with lectotype MACN A 52–31. Fossils of ''Rhynchippus'' have been found in the Agua de la Piedra and Sarmiento Formations of Argentina, the Salla and Petaca Formations of Bolivia, the Tremembé Formation of Brazil,''Rhynchippus'' at Fossilworks.org and the Moquegua Formation of |
Pleurostylodon
''Pleurostylodon'' is an extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ... genus of Notoungulata, notoungulate belonging to the family Isotemnidae. It lived during the Middle Eocene, in what is now Argentina. Description This genus is known from numerous remains, mainly cranial, allowing to reconstruct its morphology. It was approximately the size of a sheep, with an appearance evocating a tapir or a boar. ''Pleurostylodon'' had a large skull, widening in the orbital arch area, and narrowing in the posterior area of the muzzle, whose terminal part was enlarged and had small incisors ; there was no diastema after the canines. The muzzle was shorter than in more derived and specialized toxodonts such as ''Adinotherium'', and the occipital area was narrower. Several characte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eurygenium
''Eurygenium'' is an extinct genus of notoungulate belonging to the family Notohippidae. It lived during the Late Oligocene in what is today South America. Description It was a medium-sized mammal ; the best known species, ''Eurygenium pacegnum'', was approximately 80 centimeters long and weighed 10 kilograms. Its body was relatively compact, with more robust legs than its relatives, such as '' Rhynchippus''; unlike the latter, however, ''Eurygenium'' had tetradactyls forelegs and a third trochanter near the femoral midline. The skull of ''Eurygenium'' was characterized by a short and broad muzzle, with strong and laterally expanded zygomatic arches. The dentition was devoid of diastema. As in all Notohippidae, premolars and molars had a very high crown (hypsodont). The upper premolars lacked an anterolingual cingulum, while the posterolingual cingulum was reduced. The lower incisors cingulum was reduced or absent, while the lower premolars and molars had a dimple at the trigon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
