Post by DinosaurMichael on Mar 19, 2012 7:06:36 GMT -5
North American Giant Short-faced Bear - Arctodus simus
Arctodus (Greek, "bear tooth") — known as the short-faced bear or bulldog bear — is an extinct genus of bear endemic to North America during the Pleistocene ~3.0 Ma.—11,000 years ago, existing for approximately three million years. Arctodus simus may have once been Earth's largest mammalian, terrestrial carnivore. It was the most common of early North American bears, being most abundant in California. It was native to prehistoric North America from about 800,000 years ago, and became extinct about 12,500 years ago. It has been found from as far north as Ikpikpuk River, Alaska to Lowndes County, Mississippi. It is one of the largest bears in the fossil record and was among the largest mammalian land predators of all time. The type specimen came from Potter Creek Cave in Shasta County, California. Males from the Yukon region - the largest representatives of the species - would have stood about 1.80 m (5.9 ft) at the shoulder (on all fours), 4 m (13 ft) upright and may have weighed about 800 kg (1,800 lb). Arctodus simus was the largest carnivorous mammal that ever lived in North America.
Ceratosaurus - Ceratosaurus nasicornis
Ceratosaurus ( /ˌsɛrətɵˈsɔrəs/) meaning "horned lizard", in reference to the horn on its nose (Greek κερας/κερατος, keras/keratos meaning "horn" and σαυρος/sauros meaning "lizard"), was a large predatory theropod dinosaur from the Late Jurassic Period (Kimmeridgian to Tithonian), found in the Morrison Formation of North America, in Tanzania and Portugal. It was characterized by large jaws with blade-like teeth, a large, blade-like horn on the snout and a pair of hornlets over the eyes. The forelimbs were powerfully built but very short. The bones of the sacrum were fused (synsacrum) and the pelvic bones were fused together and to this structure (Sereno 1997). A row of small osteoderms was present down the middle of the back. Ceratosaurus was a fairly typical theropod, with a large head, short forelimbs, robust hind legs, and a long tail. The skull of Ceratosaurus was quite large in proportion to the rest of its body. Each premaxilla contained only three teeth, and each maxilla (the main tooth-bearing bones in the upper jaw) held between twelve and fifteen flattened, exceptionally long teeth. Each dentary (the main tooth-bearing bone in the lower jaw) bore eleven to fifteen teeth. The prominent nose horn is formed from protuberances of the nasal bones. A juvenile specimen is known in which the two halves of the horn are not yet fused together. In addition to the large nasal horn, Ceratosaurus possessed smaller hornlike ridges in front of each eye, similar to those of Allosaurus. These ridges were formed by enlargement of the lacrimal bones. Uniquely among theropods, Ceratosaurus possessed dermal armor, in the form of small osteoderms running down the middle of its back. The tail of Ceratosaurus comprised about half of the body's total length. It was thin and flexible, with high vertebral spines. The type specimen was an individual about 17.5 feet (5.3 m) long; it is not clear whether this animal was fully grown. David B. Norman (1985) estimated that the maximum length of Ceratosaurus was 20 feet (6 m). A particularly large Ceratosaurus specimen from the Cleveland-Lloyd Quarry (UUVP 81), discovered in the mid-1960s, may have been up to 28.8 feet (8.8 m) long. Marsh (1884) suggested that Ceratosaurus weighed about half as much as Allosaurus. In Predatory Dinosaurs of the World, published in 1988, Gregory S. Paul estimated that the C. nasicornis holotype skeleton came from an animal weighing about 524 kilograms (1,160 lb). A large femur from the Cleveland-Lloyd Quarry represents a much bigger and heavier individual, whose bulk was estimated by Paul at about 980 kilograms (2,200 lb).
Arctodus (Greek, "bear tooth") — known as the short-faced bear or bulldog bear — is an extinct genus of bear endemic to North America during the Pleistocene ~3.0 Ma.—11,000 years ago, existing for approximately three million years. Arctodus simus may have once been Earth's largest mammalian, terrestrial carnivore. It was the most common of early North American bears, being most abundant in California. It was native to prehistoric North America from about 800,000 years ago, and became extinct about 12,500 years ago. It has been found from as far north as Ikpikpuk River, Alaska to Lowndes County, Mississippi. It is one of the largest bears in the fossil record and was among the largest mammalian land predators of all time. The type specimen came from Potter Creek Cave in Shasta County, California. Males from the Yukon region - the largest representatives of the species - would have stood about 1.80 m (5.9 ft) at the shoulder (on all fours), 4 m (13 ft) upright and may have weighed about 800 kg (1,800 lb). Arctodus simus was the largest carnivorous mammal that ever lived in North America.
Ceratosaurus - Ceratosaurus nasicornis
Ceratosaurus ( /ˌsɛrətɵˈsɔrəs/) meaning "horned lizard", in reference to the horn on its nose (Greek κερας/κερατος, keras/keratos meaning "horn" and σαυρος/sauros meaning "lizard"), was a large predatory theropod dinosaur from the Late Jurassic Period (Kimmeridgian to Tithonian), found in the Morrison Formation of North America, in Tanzania and Portugal. It was characterized by large jaws with blade-like teeth, a large, blade-like horn on the snout and a pair of hornlets over the eyes. The forelimbs were powerfully built but very short. The bones of the sacrum were fused (synsacrum) and the pelvic bones were fused together and to this structure (Sereno 1997). A row of small osteoderms was present down the middle of the back. Ceratosaurus was a fairly typical theropod, with a large head, short forelimbs, robust hind legs, and a long tail. The skull of Ceratosaurus was quite large in proportion to the rest of its body. Each premaxilla contained only three teeth, and each maxilla (the main tooth-bearing bones in the upper jaw) held between twelve and fifteen flattened, exceptionally long teeth. Each dentary (the main tooth-bearing bone in the lower jaw) bore eleven to fifteen teeth. The prominent nose horn is formed from protuberances of the nasal bones. A juvenile specimen is known in which the two halves of the horn are not yet fused together. In addition to the large nasal horn, Ceratosaurus possessed smaller hornlike ridges in front of each eye, similar to those of Allosaurus. These ridges were formed by enlargement of the lacrimal bones. Uniquely among theropods, Ceratosaurus possessed dermal armor, in the form of small osteoderms running down the middle of its back. The tail of Ceratosaurus comprised about half of the body's total length. It was thin and flexible, with high vertebral spines. The type specimen was an individual about 17.5 feet (5.3 m) long; it is not clear whether this animal was fully grown. David B. Norman (1985) estimated that the maximum length of Ceratosaurus was 20 feet (6 m). A particularly large Ceratosaurus specimen from the Cleveland-Lloyd Quarry (UUVP 81), discovered in the mid-1960s, may have been up to 28.8 feet (8.8 m) long. Marsh (1884) suggested that Ceratosaurus weighed about half as much as Allosaurus. In Predatory Dinosaurs of the World, published in 1988, Gregory S. Paul estimated that the C. nasicornis holotype skeleton came from an animal weighing about 524 kilograms (1,160 lb). A large femur from the Cleveland-Lloyd Quarry represents a much bigger and heavier individual, whose bulk was estimated by Paul at about 980 kilograms (2,200 lb).
