Post by Deinobrontornis on Oct 25, 2011 16:51:58 GMT -5
[a href="Spinosaurus"]Spinosaurus[/a]
Spinosaurus (meaning "spine lizard") is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago.
Spinosaurus may be the largest of all known carnivorous dinosaurs, even larger than Tyrannosaurus and Giganotosaurus. Estimates published in 2005 and 2007 suggest that it was 12.6 to 18 metres (41 to 59 ft) in length and 7 to 20.9 tonnes (7.7 to 23.0 short tons) in weight. The skull of Spinosaurus was long and narrow like that of a modern crocodilian. Spinosaurus is thought to have eaten fish; evidence suggests that it lived both on land and in water like a modern crocodilian. The distinctive spines of Spinosaurus, which were long extensions of the vertebrae, grew to at least 1.65 meters (5.4 ft) long and were likely to have had skin connecting them, forming a sail-like structure, although some authors have suggested that the spines were covered in fat and formed a hump. Multiple functions have been put forward for this structure, including thermoregulation and display.
[a href="Diplodocus"]Diplodocus[/a]
One of the best-known sauropods, Diplodocus was a very large long-necked quadrupedal animal, with a long, whip-like tail. Its forelimbs were slightly shorter than its hind limbs, resulting in a largely horizontal posture. The long-necked, long-tailed animal with four sturdy legs has been mechanically compared with a suspension bridge. In fact, Diplodocus is the longest dinosaur known from a complete skeleton. The partial remains of D. hallorum have increased the estimated length, though not as much as previously thought; when first described in 1991, discoverer David Gillette calculated it may have been up to 54 m (177 ft) long, making it the longest known dinosaur (excluding those known from exceedingly poor remains, such as Amphicoelias). Some weight estimates ranged as high as 113 tons (125 US short tons). This review was based on recent findings that show that the giant tail vertebrae were actually placed further forward on the tail than Gillette originally calculated. The study shows that the complete Diplodocus skeleton at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania, on which estimates of Seismosaurus were based, had its 13th tail vertebra come from another dinosaur, throwing size estimates for Seismosaurus off by up to 30%. While dinosaurs such as Supersaurus were probably longer, fossil remains of these animals are only fragmentary. Modern mass estimates for Diplodocus (exclusive of D. hallorum) have tended to be in the 10 to 16 tonne (11–17.6 ton) range: 10 tonnes (11 tons); 11.5 tonnes (12.7 tons); 12.7 tonnes (14 tons); and 16 tonnes (17.6 tons).
The skull of Diplodocus was very small, compared with the size of the animal, which could reach up to 35 m (115 ft), of which over 6 m (20 ft) was neck. Diplodocus had small, 'peg'-like teeth that pointed forward and were only present in the anterior sections of the jaws. Its braincase was small. The neck was composed of at least fifteen vertebrae and is now believed to have been generally held parallel to the ground and unable to have been elevated much past horizontal.
Diplodocus had an extremely long tail, composed of about 80 caudal vertebrae, which is almost double the number some of the earlier sauropods had in their tails (such as Shunosaurus with 43), and far more than contemporaneous macronarians had (such as Camarasaurus with 53). There has been speculation as to whether it may have had a defensive or noisemaking (by cracking it like a coachwhip) function. The tail may have served as a counterbalance for the neck. The middle part of the tail had 'double beams' (oddly shaped bones on the underside, which gave Diplodocus its name). They may have provided support for the vertebrae, or perhaps prevented the blood vessels from being crushed if the animal's heavy tail pressed against the ground. These 'double beams' are also seen in some related dinosaurs.
Like other sauropods, the manus (front "feet") of Diplodocus were highly modified, with the finger and hand bones arranged into a vertical column, horseshoe-shaped in cross section. Diplodocus lacked claws on all but one digit of the front limb, and this claw was unusually large relative to other sauropods, flattened from side to side, and detached from the bones of the hand. The function of this unusually specialized claw is unknown.
Spinosaurus (meaning "spine lizard") is a genus of theropod dinosaur which lived in what is now North Africa, from the lower Albian to lower Cenomanian stages of the Cretaceous period, about 112 to 97 million years ago.
Spinosaurus may be the largest of all known carnivorous dinosaurs, even larger than Tyrannosaurus and Giganotosaurus. Estimates published in 2005 and 2007 suggest that it was 12.6 to 18 metres (41 to 59 ft) in length and 7 to 20.9 tonnes (7.7 to 23.0 short tons) in weight. The skull of Spinosaurus was long and narrow like that of a modern crocodilian. Spinosaurus is thought to have eaten fish; evidence suggests that it lived both on land and in water like a modern crocodilian. The distinctive spines of Spinosaurus, which were long extensions of the vertebrae, grew to at least 1.65 meters (5.4 ft) long and were likely to have had skin connecting them, forming a sail-like structure, although some authors have suggested that the spines were covered in fat and formed a hump. Multiple functions have been put forward for this structure, including thermoregulation and display.
[a href="Diplodocus"]Diplodocus[/a]
One of the best-known sauropods, Diplodocus was a very large long-necked quadrupedal animal, with a long, whip-like tail. Its forelimbs were slightly shorter than its hind limbs, resulting in a largely horizontal posture. The long-necked, long-tailed animal with four sturdy legs has been mechanically compared with a suspension bridge. In fact, Diplodocus is the longest dinosaur known from a complete skeleton. The partial remains of D. hallorum have increased the estimated length, though not as much as previously thought; when first described in 1991, discoverer David Gillette calculated it may have been up to 54 m (177 ft) long, making it the longest known dinosaur (excluding those known from exceedingly poor remains, such as Amphicoelias). Some weight estimates ranged as high as 113 tons (125 US short tons). This review was based on recent findings that show that the giant tail vertebrae were actually placed further forward on the tail than Gillette originally calculated. The study shows that the complete Diplodocus skeleton at the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania, on which estimates of Seismosaurus were based, had its 13th tail vertebra come from another dinosaur, throwing size estimates for Seismosaurus off by up to 30%. While dinosaurs such as Supersaurus were probably longer, fossil remains of these animals are only fragmentary. Modern mass estimates for Diplodocus (exclusive of D. hallorum) have tended to be in the 10 to 16 tonne (11–17.6 ton) range: 10 tonnes (11 tons); 11.5 tonnes (12.7 tons); 12.7 tonnes (14 tons); and 16 tonnes (17.6 tons).
The skull of Diplodocus was very small, compared with the size of the animal, which could reach up to 35 m (115 ft), of which over 6 m (20 ft) was neck. Diplodocus had small, 'peg'-like teeth that pointed forward and were only present in the anterior sections of the jaws. Its braincase was small. The neck was composed of at least fifteen vertebrae and is now believed to have been generally held parallel to the ground and unable to have been elevated much past horizontal.
Diplodocus had an extremely long tail, composed of about 80 caudal vertebrae, which is almost double the number some of the earlier sauropods had in their tails (such as Shunosaurus with 43), and far more than contemporaneous macronarians had (such as Camarasaurus with 53). There has been speculation as to whether it may have had a defensive or noisemaking (by cracking it like a coachwhip) function. The tail may have served as a counterbalance for the neck. The middle part of the tail had 'double beams' (oddly shaped bones on the underside, which gave Diplodocus its name). They may have provided support for the vertebrae, or perhaps prevented the blood vessels from being crushed if the animal's heavy tail pressed against the ground. These 'double beams' are also seen in some related dinosaurs.
Like other sauropods, the manus (front "feet") of Diplodocus were highly modified, with the finger and hand bones arranged into a vertical column, horseshoe-shaped in cross section. Diplodocus lacked claws on all but one digit of the front limb, and this claw was unusually large relative to other sauropods, flattened from side to side, and detached from the bones of the hand. The function of this unusually specialized claw is unknown.
