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Megalocnidae
Megalocnidae is an extinct family of sloths, native to the islands of the Greater Antilles from the Early Oligocene to the Mid-Holocene. They are known from Cuba, Hispaniola and Puerto Rico, but are absent from Jamaica. While they were formerly placed in the Megalonychidae alongside two-toed sloths and ground sloths like ''Megalonyx'', recent mitochondrial DNA and collagen sequencing studies place them as the earliest diverging group basal to all other sloths. They displayed significant diversity in body size and lifestyle, with ''Megalocnus'' being terrestrial and probably weighing several hundred kilograms, while ''Neocnus'' was likely arboreal and similar in weight to extant tree sloths, at less than 10 kilograms. Origin It is thought that sloths arrived in the Caribbean from South America (where they arose) around the Eocene-Oligocene boundary about 33 million years ago, when there was a significant sea level drop caused by a glaciation episode. This has been associate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sloth
Sloths are a group of Neotropical xenarthran mammals constituting the suborder Folivora, including the extant arboreal tree sloths and extinct terrestrial ground sloths. Noted for their slowness of movement, tree sloths spend most of their lives hanging upside down in the trees of the tropical rainforests of South America and Central America. Sloths are considered to be most closely related to anteaters, together making up the xenarthran order Pilosa. There are six extant sloth species in two genera – '' Bradypus'' (three–toed sloths) and '' Choloepus'' (two–toed sloths). Despite this traditional naming, all sloths have three toes on each rear limb-- although two-toed sloths have only two digits on each forelimb. The two groups of sloths are from different, distantly related families, and are thought to have evolved their morphology via parallel evolution from terrestrial ancestors. Besides the extant species, many species of ground sloths ranging up to the size of ele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ground Sloth
Ground sloths are a diverse group of extinct sloths in the mammalian superorder Xenarthra. The term is used to refer to all extinct sloths because of the large size of the earliest forms discovered, compared to existing tree sloths. The Caribbean ground sloths, the most recent survivors, lived in the Antilles, possibly until 1550 BCE. However, radiocarbon dating suggests an age of between 2819 and 2660 BCE for the last occurrence of ''Megalocnus'' in Cuba. Ground sloths had been extinct on the mainland of North and South America for 10,000 years or more. They survived 5,000–6,000 years longer in the Caribbean than on the American mainland, which correlates with the later colonization of this area by humans. Much ground sloth evolution took place during the late Paleogene and Neogene of South America, while the continent was isolated. At their earliest appearance in the fossil record, the ground sloths were already distinct at the family level. The presence ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megalonychidae
Megalonychidae is an extinct family of sloths including the extinct ''Megalonyx''. Megalonychids first appeared in the early Oligocene, about 35 million years (Ma) ago, in southern Argentina (Patagonia). There is actually one possible find dating to the Eocene, about 40 Ma ago, on Seymour Island in Antarctica (which was then still connected to South America). They first reached North America by island-hopping across the Central American Seaway, about 9 million years ago, prior to formation of the Isthmus of Panama about 2.7 million years ago (which led to the main pulse of the Great American Interchange). Some megalonychid lineages increased in size as time passed. The first species of these were small and may have been partly tree-dwelling, whereas the Pliocene (about 5 to 2 million years ago) species were already approximately half the size of the huge Late Pleistocene ''Megalonyx jeffersonii'' from the last ice age.J.L. White (1993) It was formerly believed, based on morpholo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parocnus
''Parocnus'' is an extinct genus of sloth native to Cuba and Hispaniola, belonging to the family Megalocnidae. It was a large terrestrial ground sloth, being the second largest Caribbean sloth after ''Megalocnus ''Megalocnus'' ("great sloth" in Greek) is a genus of extinct large ground sloths that were native to Cuba during the Pleistocene and Holocene epochs. They were among the largest of the Caribbean sloths (Megalocnidae), with individuals estimate ...''. Taxonomy After * †''Parocnus browni'' Pleistocene to Holocene, Cuba * †''Parocnus serus'' Pleistocene to Holocene, Hispaniola (synonym ''Megalocnus zile'') *†''Parocnus dominicanus'' Pleistocene to Holocene, Hispaniola References {{Taxonbar, from=Q108336505 Prehistoric sloths Mammals of the Caribbean Prehistoric placental genera Fossil taxa described in 1929 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Two-toed Sloth
''Choloepus'' is a genus of xenarthran mammals of Central and South America within the monotypic family Choloepodidae, consisting of two-toed sloths, sometimes also called two-fingered sloths. The two species of ''Choloepus'' (which means "lame foot"), Linnaeus's two-toed sloth (''Choloepus didactylus'') and Hoffmann's two-toed sloth (''Choloepus hoffmanni''), were formerly believed on the basis of morphological studies to be the only surviving members of the sloth family Megalonychidae, but have now been shown by molecular results to be closest to extinct ground sloths of the family Mylodontidae. Extant species Evolution A study of retrovirus and mitochondrial DNA suggests that ''C. didactylus'' and ''C. hoffmani'' diverged 6 to 7 million years ago. Furthermore, based on cytochrome c oxidase subunit I sequences, a similar divergence date ( years ago) between the two populations of ''C. hofmanni'' separated by the Andes has been reported. Their ancestors evolved with mari ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megalocnus
''Megalocnus'' ("great sloth" in Greek) is a genus of extinct large ground sloths that were native to Cuba during the Pleistocene and Holocene epochs. They were among the largest of the Caribbean sloths (Megalocnidae), with individuals estimated to have weighed up to 270 kg (595 lbs) to 200 kg (440 lbs), around the size of a black bear when alive.Steadman, D. W., Martin, P. S., MacPhee, R. D., Jull, A. T., McDonald, H. G., Woods, C. A., ... & Hodgins, G. W. (2005). Asynchronous extinction of late Quaternary sloths on continents and islands. ''Proceedings of the National Academy of Sciences'', ''102''(33), 11763-11768. Its relatives include other megalocnid sloths, such as '' Acratocnus'', '' Mesocnus'', '' Miocnus'', '' Neocnus and'' '' Parocnus''. The former species ''M. zile'' from Hispaniola is currently thought to be a junior synonym of ''Parocnus serus''. Etymology ''Megalocnus'', the generic name, means "great sloth" after the similarities between the holotype's caninif ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acratocnus
''Acratocnus'' is an extinct genus of ground sloths that were found on Cuba, Hispaniola (today the Dominican Republic and Haiti), and Puerto Rico. Classification Like all of the Antillean sloths, ''Acratocnus'' was formerly thought on the basis of morphological evidence to be a member of the family Megalonychidae, which was also thought to include '' Choloepus'', the two-toed tree sloths. Recent molecular evidence has clarified that Caribbean sloths represent a separate basal branch of the sloth radiation, now placed in the family Megalocnidae. Location Fossils of ''Acratocnus'' were found on the islands of Puerto Rico, Cuba, and Hispaniola, where they inhabited the montane forests of the highlands. The Puerto Rican ground sloth, ''Acratocnus odontrigonus'' is known from several poorly documented cave excavations in northwestern Puerto Rico. The various species are regarded as being semi-arboreal because of their (relatively speaking) small size and their large hooked cla ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Imagocnus
''Imagocnus'' is an extinct genus of ground sloth from the Early Miocene (Burdigalian) Lagunitas Formation, Cuba, Lagunitas Formation of Cuba. Description This sloth resided in the Antilles and showed a range of body size, from ''Parocnus''-sized to ''Megalocnus''-sized or larger. Its relationships to Pilosans of the Caribbean, other Antillean sloths are not immediately clear, though the genera ''Megalocnus'' and ''Parocnus'', other ground sloths, are its most likely relatives. See also * Pilosans of the Caribbean References Prehistoric sloths Prehistoric placental genera Miocene xenarthrans Burdigalian life Miocene mammals of North America Hemingfordian Neogene Cuba Fossils of Cuba Fossil taxa described in 1994 {{paleo-mammal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neocnus
''Neocnus'' is an extinct genus of ground sloth, whose species ranged across Cuba and Hispaniola (today split between Haiti and the Dominican Republic). ''Neocnus'' would have resembled a typical ground sloth, though much smaller, with a longer tail and a broad trunk, as well as lissome limbs and long claws. This sloth was known for having caudal vertebrae that were broad, a trait shared with other ground sloths, indicating that this animal, like the tamandua of today, likely used its tail to stand upright. The caniniform teeth of the ''Neocnus'' were large and triangular, and its skull was deep and had a large, sagittal crest which, when used with the deep mandible likely allowed strong exertion by the masticatory muscles. The fossils of this sloth were found in Haitian cave deposits. They have been dated to as recently as 4391 BP, calibrated to c. 5000 BP. It is theorized that this sloth, in common with other Antillean sloths, was most likely hunted to extinction by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Collagen
Collagen () is the main structural protein in the extracellular matrix found in the body's various connective tissues. As the main component of connective tissue, it is the most abundant protein in mammals, making up from 25% to 35% of the whole-body protein content. Collagen consists of amino acids bound together to form a triple helix of elongated fibril known as a collagen helix. It is mostly found in connective tissue such as cartilage, bones, tendons, ligaments, and skin. Depending upon the degree of mineralization, collagen tissues may be rigid (bone) or compliant (tendon) or have a gradient from rigid to compliant (cartilage). Collagen is also abundant in corneas, blood vessels, the gut, intervertebral discs, and the dentin in teeth. In muscle tissue, it serves as a major component of the endomysium. Collagen constitutes one to two percent of muscle tissue and accounts for 6% of the weight of the skeletal muscle tissue. The fibroblast is the most common cell that crea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caviomorph Rodent
Caviomorpha is the rodent infraorder or parvorder that unites all New World hystricognaths. It is supported by both fossil and molecular evidence. The Caviomorpha was for a time considered to be a separate order outside the Rodentia, but is now accepted as a genuine part of the rodents. Caviomorphs include the extinct Heptaxodontidae (giant hutias) and extant families of chinchilla rats, hutias, guinea pigs and the capybara, chinchillas and viscachas, tuco-tucos, agoutis, pacas, pacaranas, spiny rats, New World porcupines, coypu and octodonts (Vassallo and Antenucci, 2015). Origin The first known rodent fossils in South America are represented by the three taxa ''Cachiyacuy contamanensis'', ''C. kummeli'', and ''Canaanimys maquiensis'', as well as teeth from ''Eobranisamys'' sp. (Dasyproctidae) and ''Eospina'' sp., the latter two found also in the Santa Rosa fauna from the late Eocene or early Oligocene. By the late Oligocene, all superfamilies and most families of ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammals Of The Caribbean
A unique and diverse albeit phylogenetically restricted mammal fauna is known from the Caribbean region. The region—specifically, all islands in the Caribbean Sea (except for small islets close to the continental mainland) and the Bahamas, Turks and Caicos Islands, and Barbados, which are not in the Caribbean Sea but biogeographically belong to the same Caribbean bioregion—has been home to several families found nowhere else, but much of this diversity is now extinct. The bat faunas of much of the Caribbean show similarities that led to the proposal of a distinct Caribbean faunal region, bounded by "Koopman's Line". This region excludes several of the region's islands, including the Grenadines, Grenada, Trinidad, Tobago, and other islands near the American mainland, such as Margarita, Isla Escudo de Veraguas, Rosario Islands, Cozumel, and the Florida Keys. The faunas of islands outside Koopman's Line are similar to those of the adjacent mainland, though usually smaller; in con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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