Post by DinosaurMichael on Jun 29, 2012 9:34:37 GMT -5
Megatherium - Megatherium americanum
Megatherium ("Great Beast") was a genus of elephant-sized ground sloths endemic to Central America and South America that lived from the Pliocene through Pleistocene existing approximately 5.3 million years. Its size was exceeded by only a few other land mammals, including mammoths and the even larger Paraceratherium. The rhinoceros-sized Promegatherium is suggested to be the ancestor of Megatherium. Megatherium was one of the largest mammals known, weighing up to eight tons, about as much as an African bull elephant. Although it was primarily a quadruped, its footprints show that it was capable of assuming a bipedal stance. When it stood on its hind legs it was about twenty feet (6 m) tall, twice the height of an elephant. 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. 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. Its jaw is believed to have housed a long tongue, which it would then use to pull leaves into its mouth, similar to the modern tree sloth. Some recent morpho-functional analysis indicates that M. americanum was adapted for strong vertical biting. The teeth are hypsodont and bilophodont, and the sagittal section of each loph is triangular with a sharp edge. This suggests the teeth were used for cutting, rather than grinding, and that hard fibrous food was not the primary dietary component. Megatherium americanum skeleton, Muséum national d'Histoire naturelle, ParisRichard Fariña and Ernesto Blanco of the Universidad de la República in Montevideo have analysed a fossil skeleton of M. americanum and discovered that its olecranon - the part of the elbow to which the triceps muscle attaches - was very short. This adaptation is found in carnivores and optimises speed rather than strength. The researchers say this would have enabled M. americanum to use its claws like daggers. They suggest that to add nutrients to its diet, Megatherium may have taken over the kills of Smilodon. Based on the estimated strength and mechanical advantage of its biceps, it has been proposed that Megatherium could have overturned adult glyptodonts (large, armored xenarthrans, related to armadillos) as a means of scavenging or hunting these animals. However, other zoologists have described this proposal as "fanciful".
Acrocanthosaurus - Acrocanthosaurus atokensis
Acrocanthosaurus ( /ˌækrɵˌkænθɵˈsɔrəs/ ak-rə-kan-thə-sor-əs; meaning "high-spined lizard") is a genus of theropod dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous. Like most dinosaur genera, Acrocanthosaurus contains only a single species, A. atokensis. Its fossil remains are found mainly in the U.S. states of Oklahoma, Texas, and Arkansas, although teeth attributed to Acrocanthosaurus have been found as far east as Maryland. Acrocanthosaurus was a bipedal predator. As the name suggests, it is best known for the high neural spines on many of its vertebrae, which most likely supported a ridge of muscle over the animal's neck, back and hips. Acrocanthosaurus was one of the largest theropods, approaching 12 meters (40 ft) in length, and weighing up to 6–7 metric tons (6.5–7.5 short tons). Large theropod footprints discovered in Texas may have been made by Acrocanthosaurus, although there is no direct association with skeletal remains. Recent discoveries have elucidated many details of its anatomy, allowing for specialized studies focusing on its brain structure and forelimb function. Acrocanthosaurus was the largest theropod in its ecosystem and likely an apex predator which possibly preyed on large sauropods and ornithopods. Although slightly smaller than colossal relatives like Giganotosaurus, Acrocanthosaurus was still among the largest theropods ever to exist. The longest known individual measured 11.5 meters (38 ft) from snout to tail tip and weighed an estimated 6,000–7,000 kilograms (13,000–15,000 lb). Its skull alone was nearly 1.3 meters (4.3 ft) in length. The most notable feature of Acrocanthosaurus was its row of tall neural spines, located on the vertebrae of the neck, back, hips and upper tail, which could be more than 2.5 times the height of the vertebrae from which they extended.
Megatherium ("Great Beast") was a genus of elephant-sized ground sloths endemic to Central America and South America that lived from the Pliocene through Pleistocene existing approximately 5.3 million years. Its size was exceeded by only a few other land mammals, including mammoths and the even larger Paraceratherium. The rhinoceros-sized Promegatherium is suggested to be the ancestor of Megatherium. Megatherium was one of the largest mammals known, weighing up to eight tons, about as much as an African bull elephant. Although it was primarily a quadruped, its footprints show that it was capable of assuming a bipedal stance. When it stood on its hind legs it was about twenty feet (6 m) tall, twice the height of an elephant. 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. 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. Its jaw is believed to have housed a long tongue, which it would then use to pull leaves into its mouth, similar to the modern tree sloth. Some recent morpho-functional analysis indicates that M. americanum was adapted for strong vertical biting. The teeth are hypsodont and bilophodont, and the sagittal section of each loph is triangular with a sharp edge. This suggests the teeth were used for cutting, rather than grinding, and that hard fibrous food was not the primary dietary component. Megatherium americanum skeleton, Muséum national d'Histoire naturelle, ParisRichard Fariña and Ernesto Blanco of the Universidad de la República in Montevideo have analysed a fossil skeleton of M. americanum and discovered that its olecranon - the part of the elbow to which the triceps muscle attaches - was very short. This adaptation is found in carnivores and optimises speed rather than strength. The researchers say this would have enabled M. americanum to use its claws like daggers. They suggest that to add nutrients to its diet, Megatherium may have taken over the kills of Smilodon. Based on the estimated strength and mechanical advantage of its biceps, it has been proposed that Megatherium could have overturned adult glyptodonts (large, armored xenarthrans, related to armadillos) as a means of scavenging or hunting these animals. However, other zoologists have described this proposal as "fanciful".
Acrocanthosaurus - Acrocanthosaurus atokensis
Acrocanthosaurus ( /ˌækrɵˌkænθɵˈsɔrəs/ ak-rə-kan-thə-sor-əs; meaning "high-spined lizard") is a genus of theropod dinosaur that existed in what is now North America during the Aptian and early Albian stages of the Early Cretaceous. Like most dinosaur genera, Acrocanthosaurus contains only a single species, A. atokensis. Its fossil remains are found mainly in the U.S. states of Oklahoma, Texas, and Arkansas, although teeth attributed to Acrocanthosaurus have been found as far east as Maryland. Acrocanthosaurus was a bipedal predator. As the name suggests, it is best known for the high neural spines on many of its vertebrae, which most likely supported a ridge of muscle over the animal's neck, back and hips. Acrocanthosaurus was one of the largest theropods, approaching 12 meters (40 ft) in length, and weighing up to 6–7 metric tons (6.5–7.5 short tons). Large theropod footprints discovered in Texas may have been made by Acrocanthosaurus, although there is no direct association with skeletal remains. Recent discoveries have elucidated many details of its anatomy, allowing for specialized studies focusing on its brain structure and forelimb function. Acrocanthosaurus was the largest theropod in its ecosystem and likely an apex predator which possibly preyed on large sauropods and ornithopods. Although slightly smaller than colossal relatives like Giganotosaurus, Acrocanthosaurus was still among the largest theropods ever to exist. The longest known individual measured 11.5 meters (38 ft) from snout to tail tip and weighed an estimated 6,000–7,000 kilograms (13,000–15,000 lb). Its skull alone was nearly 1.3 meters (4.3 ft) in length. The most notable feature of Acrocanthosaurus was its row of tall neural spines, located on the vertebrae of the neck, back, hips and upper tail, which could be more than 2.5 times the height of the vertebrae from which they extended.
. You also don't seem to grasp that maneuverability is not speed, although even in the former respect, theropods were not poor like ignoramuses like to think they were.