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Mesotheriinae
Mesotheriidae ("Middle Beasts") is an extinct family of notoungulate mammals known from the Oligocene through the Pleistocene of South America. Mesotheriids were small to medium-sized herbivorous mammals adapted for digging. Characteristics Mesotheriids were small to medium-sized notoungulates; larger forms were approximately the size of a sheep. Shockey et al., 2007 Additionally, the family is characterized by specializations of the teeth and skeleton. In the dentition, all mesotheriids have ever-growing incisors with enamel restricted to the anterior surface, a condition termed gliriform, as it also occurs in Glires (rodents and lagomorphs). The cheek teeth ( premolars and molars) of mesotheriids are high-crowned (hypsodont) and in advanced members of the family, the cheek teeth are also ever-growing. Mesotheriid skeletons are heavily built and show features associated with digging in living mammals. In particular, fossorial characteristics of mesotheriids include deeply ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesotheriinae
Mesotheriidae ("Middle Beasts") is an extinct family of notoungulate mammals known from the Oligocene through the Pleistocene of South America. Mesotheriids were small to medium-sized herbivorous mammals adapted for digging. Characteristics Mesotheriids were small to medium-sized notoungulates; larger forms were approximately the size of a sheep. Shockey et al., 2007 Additionally, the family is characterized by specializations of the teeth and skeleton. In the dentition, all mesotheriids have ever-growing incisors with enamel restricted to the anterior surface, a condition termed gliriform, as it also occurs in Glires (rodents and lagomorphs). The cheek teeth ( premolars and molars) of mesotheriids are high-crowned (hypsodont) and in advanced members of the family, the cheek teeth are also ever-growing. Mesotheriid skeletons are heavily built and show features associated with digging in living mammals. In particular, fossorial characteristics of mesotheriids include deeply ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Typotheriopsis
''Typotheriopsis'' is an extinct genus of Notoungulate, belonging to the family Mesotheriidae, which included several small sized Meridiungulates specialized in digging. It is considered as the sister taxon of the clade including ''Mesotherium'' and ''Pseudotypotherium''. Its fossils are known from the Chasicoan and the Huayquerian periods, notably among Late Miocene rocks from the Arroyo Chasicó Formation and the Cerro Azul Formation of Argentina. Description ''Typotheriopsis chasicoensis'' was described in 1931 by Angel Cabrera and Jorge L. Kraglievich, with a holotype composed of badly preserved cranial remains from the Arroyo Chasicó Formation of Argentina. Those remains were similar to ''Pseudotypotherium'', but included thicker teeth and less atrophied incisors than in other genera of mesotherid. Later studies expanded this list of differences between ''Typotheriopsis'' and ''Pseudotypotherium''. It was large for a mesothere, with a broad skull, and a suborbital foss ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Altitypotherium
''Altitypotherium'' is an extinct genus of Notoungulate, belonging to the suborder Typotheria. It lived during the Early Miocene, and its fossilized remains were discovered in South America. Description This animal was vaguely similar to a wombat, and its dimensions evocate those of a raccoon ; its skull was approximately 16 centimeters long, while its total length, excluding the tail, was about 80 centimeters. It weighed around 10 kilograms. ''Altitypotherium'' had a tall and narrow snout, with only six pairs of teeth in the maxilla and mandible, a low number when compared to most other notoungulates. It had gliriform upper incisors, with a band of anterior enamel, and lower incisors protruding forward and separated from premolars and molars by a long diastema. It had high-crowned (hypsodont) teeth, and the occlusal surfaces of the molars had two enamel folds halfway through the tooth in the inner surface and outlining three dentin-filled lobes, forming an E-shaped form. The l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fiandraia
''Fiandraia'' is an extinct monotypic genus of notoungulate that lived in Uruguay during the Oligocene and the Early Miocene. It was found in the Fray Bentos Formation, in rocks dated back from the Deseadan period. The taxonomic status of ''Fiandraia'' has been historically disputed; in 1976, its discoverer, Roselli, assigned it in the family Mesotheriidae; in 1978, in Mones & Ubilla, it was considered part of Interatheriidae; McKenna & Bell, in 1997, placed it inside its own family, Fiandraiinae, itself part of Mesotheriidae; Flynn ''et al'' considered it, in 2005, as a member of the Toxodontidae instead of the Mesotheriinae Mesotheriidae ("Middle Beasts") is an extinct family of notoungulate mammals known from the Oligocene through the Pleistocene of South America. Mesotheriids were small to medium-sized herbivorous mammals adapted for digging. Characteristics M .... References Notoungulates Prehistoric placental genera Oligocene mammals of South America ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trachytherus
''Trachytherus'' is an extinct genus of mesotheriid notoungulate that lived from the Late Oligocene to the Early Miocene in what is now South America. Description ''Trachytherus'' had a relatively low, compact skull with an elongated snout, longer than in ''Mesotherium'' but very similar. The postorbital process was also smaller and the nasal bones did not extend as far as in ''Mesotherium''. The most notable difference between the two genera was in the zygomatic arch ; in the anterior region, the insertion surface of the lateral masseter was highly developed, but not as large than in ''Mesotherium''. The first upper incisor was highly developed, continuously growing (hypsodont) and arched, with an enamel band only on the labial side. The following incisors, canines and premolars were greatly reduced or vestigial. The last three premolars were molar-like, with a very complex pattern rapidly disappearing with wear. The molars were similar to those of '' Pseudotypotherium'' and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesotherium
''Mesotherium'' ("Middle Beast") is an extinct genus of mesotheriid, a long-lasting family of superficially rodent-like, burrowing notoungulates from South America. It one of the youngest notoungulates, and the last known member of Typotheria. It was first named by Étienne Serres in 1867, and through further finds now contains four species, ''M. cristatum'', ''M. hystatum'', ''M. maendrum'', and ''M. pachygnathum''. Fossils have been found in Argentina, dating to the Early-Middle Pleistocene. Etymology Serres named ''Mesotherium'' so due to his belief that it was an intermediate between rodents and pachyderms (or ungulates), due to its large upper incisors, and its size and proportions. "Serres—by a happy inspiration proposed calling it Mesotherium—as being a common centre towards which all mammalia got happily confounded," Hugh Falconer wrote Darwin in April 1863. "Bravard sent it home under the name of Typotherium as being the central type from which all mammals diverged ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
South America
South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southern subregion of a single continent called America. South America is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean; North America and the Caribbean Sea lie to the northwest. The continent generally includes twelve sovereign states: Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Guyana, Paraguay, Peru, Suriname, Uruguay, and Venezuela; two dependent territories: the Falkland Islands and South Georgia and the South Sandwich Islands; and one internal territory: French Guiana. In addition, the ABC islands of the Kingdom of the Netherlands, Ascension Island (dependency of Saint Helena, Ascension and Tristan da Cunha, a British Overseas Territory), Bouvet Island ( dependency of Norway), Pa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sheep
Sheep or domestic sheep (''Ovis aries'') are domesticated, ruminant mammals typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus ''Ovis'', in everyday usage it almost always refers to domesticated sheep. Like all ruminants, sheep are members of the order Artiodactyla, the even-toed ungulates. Numbering a little over one billion, domestic sheep are also the most numerous species of sheep. An adult female is referred to as a ''ewe'' (), an intact male as a ''ram'', occasionally a ''tup'', a castrated male as a ''wether'', and a young sheep as a ''lamb''. Sheep are most likely descended from the wild mouflon of Europe and Asia, with Iran being a geographic envelope of the domestication center. One of the earliest animals to be domesticated for agricultural purposes, sheep are raised for fleeces, meat (lamb, hogget or mutton) and milk. A sheep's wool is the most widely used animal fiber, and is usually harvested by shearing. In Commonw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
References
Reference is a relationship between objects in which one object designates, or acts as a means by which to connect to or link to, another object. The first object in this relation is said to ''refer to'' the second object. It is called a ''name'' for the second object. The second object, the one to which the first object refers, is called the '' referent'' of the first object. A name is usually a phrase or expression, or some other symbolic representation. Its referent may be anything – a material object, a person, an event, an activity, or an abstract concept. References can take on many forms, including: a thought, a sensory perception that is audible (onomatopoeia), visual (text), olfactory, or tactile, emotional state, relationship with other, spacetime coordinate, symbolic or alpha-numeric, a physical object or an energy projection. In some cases, methods are used that intentionally hide the reference from some observers, as in cryptography. References feature in many sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Skeleton
A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside the body, and the hydroskeleton, a flexible internal skeleton supported by fluid pressure. Vertebrates are animals with a vertebral column, and their skeletons are typically composed of bone and cartilage. Invertebrates are animals that lack a vertebral column. The skeletons of invertebrates vary, including hard exoskeleton shells, plated endoskeletons, or Sponge spicule, spicules. Cartilage is a rigid connective tissue that is found in the skeletal systems of vertebrates and invertebrates. Etymology The term ''skeleton'' comes . ''Sceleton'' is an archaic form of the word. Classification Skeletons can be defined by several attributes. Solid skeletons consist of hard substances, such as bone, cartilage, or cuticle. These can be further ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tooth
A tooth ( : teeth) is a hard, calcified structure found in the jaws (or mouths) 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 embryonic germ layer, the ectoderm. The general structure of teeth is similar across the vertebrates, although there is considerable variation in their form and position. The teeth of mammals have deep roots, and this pattern is also found in some fish, and in crocodilians. In most teleost fish, however, the teeth are attached to the outer surface of the bone, while in lizards they are attached to the inner surface of the jaw by one side. In cartilaginous fish, s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oligocene
The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the exact dates of the start and end of the epoch are slightly uncertain. The name Oligocene was coined in 1854 by the German paleontologist Heinrich Ernst Beyrich from his studies of marine beds in Belgium and Germany. The name comes from the Ancient Greek (''olígos'', "few") and (''kainós'', "new"), and refers to the sparsity of extant forms of molluscs. The Oligocene is preceded by the Eocene Epoch and is followed by the Miocene Epoch. The Oligocene is the third and final epoch of the Paleogene Period. The Oligocene is often considered an important time of transition, a link between the archaic world of the tropical Eocene and the more modern ecosystems of the Miocene. Major changes during the Oligocene included a global expansion o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
