Post by DinosaurMichael on Mar 25, 2012 9:31:56 GMT -5
Tyrannosaurus Rex
Tyrannosaurus ( /tɨˌrænɵˈsɔrəs/ or /taɪˌrænɵˈsɔrəs/; meaning "tyrant lizard", from Greek tyrannos (τύραννος) meaning "tyrant," and sauros (σαῦρος) meaning "lizard") is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex (rex meaning "king" in Latin), commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, at the time an island continent termed Laramidia, with a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous Period, 67 to 65.5 million years ago. It was among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event. Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to the large and powerful hindlimbs, Tyrannosaurus forelimbs were small, though unusually powerful for their size, and bore two clawed digits. Although other theropods rivaled or exceeded Tyrannosaurus rex in size, it was the largest known tyrannosaurid and one of the largest known land predators, measuring up to 12.8 m (42 ft) in length, up to 4 metres (13 ft) tall at the hips, and up to 6.8 metric tons (7.5 short tons) in weight. By far the largest carnivore in its environment, Tyrannosaurus rex may have been an apex predator, preying upon hadrosaurs and ceratopsians, although some experts have suggested it was primarily a scavenger. The debate over Tyrannosaurus as apex predator or scavenger is among the longest running in paleontology. More than 30 specimens of Tyrannosaurus rex have been identified, some of which are nearly complete skeletons. Soft tissue and proteins have been reported in at least one of these specimens. The abundance of fossil material has allowed significant research into many aspects of its biology, including life history and biomechanics. The feeding habits, physiology and potential speed of Tyrannosaurus rex are a few subjects of debate. Its taxonomy is also controversial, with some scientists considering Tarbosaurus bataar from Asia to represent a second species of Tyrannosaurus and others maintaining Tarbosaurus as a separate genus. Several other genera of North American tyrannosaurids have also been synonymized with Tyrannosaurus.
Lambeosaurus - Lambeosaurus laticaudus
Lambeosaurus ( /ˌlæmbi.ɵˈsɔrəs/ LAM-bee-ə-SOR-əs; meaning "Lambe's lizard") is a genus of hadrosaurid dinosaur that lived about 76 to 75 million years ago, in the Late Cretaceous Period (Campanian) of North America. This bipedal/quadrupedal, herbivorous dinosaur is known for its distinctive hollow cranial crest, which in the best-known species resembled a hatchet. Several possible species have been named, from Alberta (Canada), Montana (USA), and Baja California (Mexico), but only the two Canadian species are currently well known. At about 15 meters (50 ft) long, the possible Mexican species "L." laticaudus was one of the longest ornithischians. The other species were more modestly sized. Lambeosaurus was belatedly described in 1923 by William Parks, over twenty years after the first material was studied by Lawrence Lambe. The genus has had a complicated taxonomic history, in part because small-bodied crested hadrosaurids now recognized as juveniles were once thought to belong to their own genera and species. Currently, the various skulls assigned to the type species L. lambei are interpreted as showing age differences and sexual dimorphism. Lambeosaurus was closely related to the better known Corythosaurus, which is found in slightly older rocks, as well as the less well-known genera Hypacrosaurus and Olorotitan. All had unusual crests, which are now generally assumed to have served social functions like noisemaking and recognition. Lambeosaurus, best known through L. lambei, was quite similar to the more famous Corythosaurus in everything but the form of the head adornment. Compared to Corythosaurus, the crest of Lambeosaurus was shifted forward, and the hollow nasal passages within were at the front of the crest and stacked vertically. It also can be differentiated from Corythosaurus by its lack of forking nasal processes making up part of the sides of the crest, which is the only way to tell juveniles of the two genera apart: the crests took on their distinctive forms as the animals aged. In build, Lambeosaurus was like other hadrosaurids, and could move on both two legs and all fours, as shown by footprints of related animals. It had a long tail stiffened by ossified tendons that prevented it from drooping. The hands had four fingers, lacking the innermost finger of the generalized five-fingered tetrapod hand, while the second, third, and fourth fingers were bunched together and bore hooves, suggesting the animal could use the hands for support. The fifth finger was free and could be used to manipulate objects. Each foot had only the three central toes. The most distinctive feature, the crest, was different in the two well-known species. In L. lambei, it had a hatchet-like shape when the dinosaur was full-grown, and was somewhat shorter and more rounded in specimens interpreted as females. The "hatchet blade" projected in front of the eyes, and the "handle" was a solid bony rod that jutted out over the back of the skull. The "hatchet blade" had two sections: the uppermost portion was a thin bony "coxcomb" that grew out relatively late in life, when an individual neared adulthood; and the lower portion held hollow spaces that were continuations of the nasal passages. In L. magnicristatus, the "handle" was greatly reduced, and the "blade" expanded, forming a tall, exaggerated pompadour-like crest. This crest is damaged in the best overall specimen, and only the front half remains. In the lesser-known species "L." laticaudus and L. paucidens the crest is not currently known. However, "L." laticaudus can be recognized by its great size and the tall profile of its tail, which had elongated chevrons and vertebral spines like those of Hypacrosaurus. The Canadian species of Lambeosaurus appear to have been similar in size to Corythosaurus, and thus around 9.4 m long (31 ft), but "L." laticaudus is estimated at between 15 m (50 ft) and 16.5 m (54.1 ft) long, with a weight of up to 23 metric tons (25 tons). Impressions of the scales are known for several specimens; a specimen now assigned to L. lambei had a thin skin with uniform, polygonal scutes distributed in no particular order on the neck, torso, and tail. Similar scalation is known from the neck, forelimb, and foot of a specimen of L. magnicristatus, whereas the tail of "L." laticaudus had some small bony bits embedded among large hexagonal and smaller rounded scales.
Tyrannosaurus ( /tɨˌrænɵˈsɔrəs/ or /taɪˌrænɵˈsɔrəs/; meaning "tyrant lizard", from Greek tyrannos (τύραννος) meaning "tyrant," and sauros (σαῦρος) meaning "lizard") is a genus of coelurosaurian theropod dinosaur. The species Tyrannosaurus rex (rex meaning "king" in Latin), commonly abbreviated to T. rex, is a fixture in popular culture. It lived throughout what is now western North America, at the time an island continent termed Laramidia, with a much wider range than other tyrannosaurids. Fossils are found in a variety of rock formations dating to the Maastrichtian age of the upper Cretaceous Period, 67 to 65.5 million years ago. It was among the last non-avian dinosaurs to exist before the Cretaceous–Paleogene extinction event. Like other tyrannosaurids, Tyrannosaurus was a bipedal carnivore with a massive skull balanced by a long, heavy tail. Relative to the large and powerful hindlimbs, Tyrannosaurus forelimbs were small, though unusually powerful for their size, and bore two clawed digits. Although other theropods rivaled or exceeded Tyrannosaurus rex in size, it was the largest known tyrannosaurid and one of the largest known land predators, measuring up to 12.8 m (42 ft) in length, up to 4 metres (13 ft) tall at the hips, and up to 6.8 metric tons (7.5 short tons) in weight. By far the largest carnivore in its environment, Tyrannosaurus rex may have been an apex predator, preying upon hadrosaurs and ceratopsians, although some experts have suggested it was primarily a scavenger. The debate over Tyrannosaurus as apex predator or scavenger is among the longest running in paleontology. More than 30 specimens of Tyrannosaurus rex have been identified, some of which are nearly complete skeletons. Soft tissue and proteins have been reported in at least one of these specimens. The abundance of fossil material has allowed significant research into many aspects of its biology, including life history and biomechanics. The feeding habits, physiology and potential speed of Tyrannosaurus rex are a few subjects of debate. Its taxonomy is also controversial, with some scientists considering Tarbosaurus bataar from Asia to represent a second species of Tyrannosaurus and others maintaining Tarbosaurus as a separate genus. Several other genera of North American tyrannosaurids have also been synonymized with Tyrannosaurus.
Lambeosaurus - Lambeosaurus laticaudus
Lambeosaurus ( /ˌlæmbi.ɵˈsɔrəs/ LAM-bee-ə-SOR-əs; meaning "Lambe's lizard") is a genus of hadrosaurid dinosaur that lived about 76 to 75 million years ago, in the Late Cretaceous Period (Campanian) of North America. This bipedal/quadrupedal, herbivorous dinosaur is known for its distinctive hollow cranial crest, which in the best-known species resembled a hatchet. Several possible species have been named, from Alberta (Canada), Montana (USA), and Baja California (Mexico), but only the two Canadian species are currently well known. At about 15 meters (50 ft) long, the possible Mexican species "L." laticaudus was one of the longest ornithischians. The other species were more modestly sized. Lambeosaurus was belatedly described in 1923 by William Parks, over twenty years after the first material was studied by Lawrence Lambe. The genus has had a complicated taxonomic history, in part because small-bodied crested hadrosaurids now recognized as juveniles were once thought to belong to their own genera and species. Currently, the various skulls assigned to the type species L. lambei are interpreted as showing age differences and sexual dimorphism. Lambeosaurus was closely related to the better known Corythosaurus, which is found in slightly older rocks, as well as the less well-known genera Hypacrosaurus and Olorotitan. All had unusual crests, which are now generally assumed to have served social functions like noisemaking and recognition. Lambeosaurus, best known through L. lambei, was quite similar to the more famous Corythosaurus in everything but the form of the head adornment. Compared to Corythosaurus, the crest of Lambeosaurus was shifted forward, and the hollow nasal passages within were at the front of the crest and stacked vertically. It also can be differentiated from Corythosaurus by its lack of forking nasal processes making up part of the sides of the crest, which is the only way to tell juveniles of the two genera apart: the crests took on their distinctive forms as the animals aged. In build, Lambeosaurus was like other hadrosaurids, and could move on both two legs and all fours, as shown by footprints of related animals. It had a long tail stiffened by ossified tendons that prevented it from drooping. The hands had four fingers, lacking the innermost finger of the generalized five-fingered tetrapod hand, while the second, third, and fourth fingers were bunched together and bore hooves, suggesting the animal could use the hands for support. The fifth finger was free and could be used to manipulate objects. Each foot had only the three central toes. The most distinctive feature, the crest, was different in the two well-known species. In L. lambei, it had a hatchet-like shape when the dinosaur was full-grown, and was somewhat shorter and more rounded in specimens interpreted as females. The "hatchet blade" projected in front of the eyes, and the "handle" was a solid bony rod that jutted out over the back of the skull. The "hatchet blade" had two sections: the uppermost portion was a thin bony "coxcomb" that grew out relatively late in life, when an individual neared adulthood; and the lower portion held hollow spaces that were continuations of the nasal passages. In L. magnicristatus, the "handle" was greatly reduced, and the "blade" expanded, forming a tall, exaggerated pompadour-like crest. This crest is damaged in the best overall specimen, and only the front half remains. In the lesser-known species "L." laticaudus and L. paucidens the crest is not currently known. However, "L." laticaudus can be recognized by its great size and the tall profile of its tail, which had elongated chevrons and vertebral spines like those of Hypacrosaurus. The Canadian species of Lambeosaurus appear to have been similar in size to Corythosaurus, and thus around 9.4 m long (31 ft), but "L." laticaudus is estimated at between 15 m (50 ft) and 16.5 m (54.1 ft) long, with a weight of up to 23 metric tons (25 tons). Impressions of the scales are known for several specimens; a specimen now assigned to L. lambei had a thin skin with uniform, polygonal scutes distributed in no particular order on the neck, torso, and tail. Similar scalation is known from the neck, forelimb, and foot of a specimen of L. magnicristatus, whereas the tail of "L." laticaudus had some small bony bits embedded among large hexagonal and smaller rounded scales.