Post by Infinity Blade on Nov 24, 2013 6:23:47 GMT 5
Triceratops horridus
Triceratops (/tra??s?r?t?ps/ try-serr-?-tops) is a genus of herbivorous ceratopsid dinosaur that lived during the late Maastrichtian stage of the Late Cretaceous Period, around 68 to 65.5 million years ago (Mya) in what is now North America. It was one of the last non-avian dinosaur genera to appear before the Cretaceous–Paleogene extinction event.[1] The term Triceratops, which literally means "three-horned face", is derived from the Greek
- (tri-) meaning "three", ?? (kéras) meaning "horn", and ?? (ops) meaning "face".[2][3] Bearing a large bony frill and three horns on its large four-legged body, and conjuring similarities with the modern rhinoceros, Triceratops is one of the most recognizable of all dinosaurs and the best known ceratopsid. It shared the landscape with and was preyed upon by the fearsome Tyrannosaurus,[4] though it is less certain that the two did battle in the manner often depicted in traditional museum displays and popular images. The exact placement of the Triceratops genus within the ceratopsid group has been debated by paleontologists. Two species, T. horridus and T. prorsus, are considered valid although many other species have been named. Research published in 2012 suggests that the contemporaneous Torosaurus, a ceratopsid long regarded as a separate genus, represents Triceratops in its mature form,[5][6] a view not accepted by everyone.[7] A study published in 2012 by Daniel Field and Nicholas Longrich, researchers from Yale, would later disagree with this assertion upholding that the two should be classified as separate species.[8][9] Triceratops has been documented by numerous remains collected since the genus was first described in 1889, including at least one complete individual skeleton.[10] Paleontologist John Scannella observed: "It is hard to walk out into the Hell Creek Formation and not stumble upon a Triceratops weathering out of a hillside." Forty-seven complete or partial skulls were discovered in just that area during the decade 2000–2010.[11] Specimens representing life stages from hatchling to adult have been found.[12] The function of the frills and three distinctive facial horns has long inspired debate. Traditionally these have been viewed as defensive weapons against predators. More recent theories, noting the presence of blood vessels in the skull bones of ceratopsids, find it more probable that these features were primarily used in identification, courtship and dominance displays, much like the antlers and horns of modern reindeer, mountain goats, or rhinoceros beetles.[13] The theory finds additional support if Torosaurus represents the mature form of Triceratops, as this would mean the frill also developed holes (fenestrae) as individuals reached maturity, rendering the structure more useful for display than defense.[5]
Megatherium americanum
Megatherium (from the Greek mega [??], meaning "great", and therion [], "beast") was a genus of elephant-sized ground sloths endemic to Central and South America that lived from the late Pliocene through the end of the Pleistocene.[1] Its size was exceeded by only a few other land mammals, including mammoths and Paraceratherium. Megatherium was one of the largest land mammals known, weighing up to 4 tonnes [2] and up to 6 m (20 ft) in length from head to tail.[3] It is the largest known ground sloth, as big as modern elephants, and would have only been exceeded in its time by a few species of mammoth. The group is known primarily from its largest species, M. americanum. Megatherium species were members of the abundant Pleistocene megafauna, large mammals that lived during the Pleistocene epoch. Megatherium had a robust skeleton with a large pelvic girdle and a broad muscular tail. Its large size enabled it to feed at heights unreachable by other contemporary herbivores. Rising on its powerful hind legs and using its tail to form a tripod, Megatherium could support its massive body weight while using the curved claws on its long forelegs to pull down branches with the choicest leaves. This sloth, like a modern anteater, walked on the sides of its feet because its claws prevented it from putting them flat on the ground. Although it was primarily a quadruped, its trackways show that it was capable of bipedal locomotion. Biomechanical analysis also suggests it had adaptations to bipedalism.[4] Its jaw, by some, is believed to have housed a long tongue, which it would use to pull leaves into its mouth, similar to the modern tree sloth. However, others suggest that some of the elements in Megatherium's oral cavity were fused together: a rigidly articulated stylohyal and epihyal, and the apparatus lies farther anteriorly, which together with the elongated, steeply inclined mandibular symphysis, indicates a relatively shorter geniohyoid muscle and thus more limited capacity for tongue protrusion.[5] It was well adapted for strong, predominantly orthal movement for eating rough vegetation. Megatherium possessed the narrowest muzzle of all ground sloths from the Pleistocene. This leads paleobiologists to believe that it was a very selective eater. It had the ability to pick and choose which leaves and twigs it would consume. Megatherium had a large narrow prehensile lip that was capable of grabbing and tearing off particular leaves and twigs and other sorts of vegetation.[6]
Triceratops (/tra??s?r?t?ps/ try-serr-?-tops) is a genus of herbivorous ceratopsid dinosaur that lived during the late Maastrichtian stage of the Late Cretaceous Period, around 68 to 65.5 million years ago (Mya) in what is now North America. It was one of the last non-avian dinosaur genera to appear before the Cretaceous–Paleogene extinction event.[1] The term Triceratops, which literally means "three-horned face", is derived from the Greek
- (tri-) meaning "three", ?? (kéras) meaning "horn", and ?? (ops) meaning "face".[2][3] Bearing a large bony frill and three horns on its large four-legged body, and conjuring similarities with the modern rhinoceros, Triceratops is one of the most recognizable of all dinosaurs and the best known ceratopsid. It shared the landscape with and was preyed upon by the fearsome Tyrannosaurus,[4] though it is less certain that the two did battle in the manner often depicted in traditional museum displays and popular images. The exact placement of the Triceratops genus within the ceratopsid group has been debated by paleontologists. Two species, T. horridus and T. prorsus, are considered valid although many other species have been named. Research published in 2012 suggests that the contemporaneous Torosaurus, a ceratopsid long regarded as a separate genus, represents Triceratops in its mature form,[5][6] a view not accepted by everyone.[7] A study published in 2012 by Daniel Field and Nicholas Longrich, researchers from Yale, would later disagree with this assertion upholding that the two should be classified as separate species.[8][9] Triceratops has been documented by numerous remains collected since the genus was first described in 1889, including at least one complete individual skeleton.[10] Paleontologist John Scannella observed: "It is hard to walk out into the Hell Creek Formation and not stumble upon a Triceratops weathering out of a hillside." Forty-seven complete or partial skulls were discovered in just that area during the decade 2000–2010.[11] Specimens representing life stages from hatchling to adult have been found.[12] The function of the frills and three distinctive facial horns has long inspired debate. Traditionally these have been viewed as defensive weapons against predators. More recent theories, noting the presence of blood vessels in the skull bones of ceratopsids, find it more probable that these features were primarily used in identification, courtship and dominance displays, much like the antlers and horns of modern reindeer, mountain goats, or rhinoceros beetles.[13] The theory finds additional support if Torosaurus represents the mature form of Triceratops, as this would mean the frill also developed holes (fenestrae) as individuals reached maturity, rendering the structure more useful for display than defense.[5] Megatherium americanum
Megatherium (from the Greek mega [
??], meaning "great", and therion [], "beast") was a genus of elephant-sized ground sloths endemic to Central and South America that lived from the late Pliocene through the end of the Pleistocene.[1] Its size was exceeded by only a few other land mammals, including mammoths and Paraceratherium. Megatherium was one of the largest land mammals known, weighing up to 4 tonnes [2] and up to 6 m (20 ft) in length from head to tail.[3] It is the largest known ground sloth, as big as modern elephants, and would have only been exceeded in its time by a few species of mammoth. The group is known primarily from its largest species, M. americanum. Megatherium species were members of the abundant Pleistocene megafauna, large mammals that lived during the Pleistocene epoch. Megatherium had a robust skeleton with a large pelvic girdle and a broad muscular tail. Its large size enabled it to feed at heights unreachable by other contemporary herbivores. Rising on its powerful hind legs and using its tail to form a tripod, Megatherium could support its massive body weight while using the curved claws on its long forelegs to pull down branches with the choicest leaves. This sloth, like a modern anteater, walked on the sides of its feet because its claws prevented it from putting them flat on the ground. Although it was primarily a quadruped, its trackways show that it was capable of bipedal locomotion. Biomechanical analysis also suggests it had adaptations to bipedalism.[4] Its jaw, by some, is believed to have housed a long tongue, which it would use to pull leaves into its mouth, similar to the modern tree sloth. However, others suggest that some of the elements in Megatherium's oral cavity were fused together: a rigidly articulated stylohyal and epihyal, and the apparatus lies farther anteriorly, which together with the elongated, steeply inclined mandibular symphysis, indicates a relatively shorter geniohyoid muscle and thus more limited capacity for tongue protrusion.[5] It was well adapted for strong, predominantly orthal movement for eating rough vegetation. Megatherium possessed the narrowest muzzle of all ground sloths from the Pleistocene. This leads paleobiologists to believe that it was a very selective eater. It had the ability to pick and choose which leaves and twigs it would consume. Megatherium had a large narrow prehensile lip that was capable of grabbing and tearing off particular leaves and twigs and other sorts of vegetation.[6]
