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18th September 2010
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Jurrasic period
ayo mari kita review sejarah sebelum adanya manusia...
  The Jurassic period (199.6 million to 145.5 million years ago) was characterized by a warm, wet climate that gave rise to lush vegetation and abundant life. Many new dinosaurs emerged�in great numbers. Among them were stegosaurs, brachiosaurs, allosaurs, and many others.  Four women at the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing, China, underscore a 19-foot (5.7-meter), 200-million-year-old ichthyosaur fossil from southern China. Although its name is Greek for "fish lizard," Ichthyosaurus was no fish�it was a reptile that swam the Mesozoic oceans.  The late Jurassic Stegosaurus, like the pair walking through a North American forest in this illustration, was a slow-moving, plant-eating dinosaur that grew as long as 30 feet (9 meters) and as much as 2 tons. Its most impressive feature was a row of large plates and tail spines down the length of its back�some more than three feet (one meter) tall.  A herd of brachiosaurs congregates on a forested coast in this artist's depiction. At up to 92 feet (28 meters) and 50 tons, these sauropods (large, herbivorous dinosaurs) were much larger than any land animal alive today. Long, lean limbs, high shoulders, and a 30-foot-long (9-meter-long) neck allowed Brachiosaurus to graze from the treetops of North America and parts of Africa, where its fossils have been found.  Ghosts of an earlier age, an Allosaurus and a Stegosaurus brace for battle at the Denver Museum in Colorado. Most museum exhibits of dinosaurs do not use actual dinosaur bones, but rather molds and casts. Technicians create fiberglass replicas of bones that are mounted and posed in lifelike positions on metal frames.  An Allosaurus tramps through a Mesozoic-era forest in this artist's depiction. Allosaurus was the top predatory dinosaur of the late Jurassic period in North America. Not a particularly fast runner, it likely ambushed unsuspecting prey as it passed by.  A dig in Dry Mesa, Colorado, revealed these Jurassic jewels: claws from a creature now extinct. All theropods (bipedal dinosaurs that included T. rex and Velociraptor) possessed curved, hooklike claws on their hands and feet, similar to today's birds of prey. Each claw ended with a sharp point ideally suited for digging into the flesh of prey. When worn down, bony claws developed a sharp edge ideal for cutting and slashing.  Paleontologists in China's Henan Basin discovered this nest of fossilized eggs laid by the Jurassic duck-billed herbivore Hadrosaurus. Current evidence suggests all dinosaurs laid eggs of a wide variety of shapes and sizes�from 3 inches (8 centimeters) to 21 inches (53 centimeters), round or elliptical. Dinosaur eggs were perforated with tiny holes, which allowed life-giving oxygen to enter.  The late-Jurassic Archaeopteryx lithographica, shown here with legs akimbo and wings outspread, is believed by many to be the world's first bird. Found in the Solnhofen Limestone Formation in Bavaria, Germany, Archaeopteryx lithographica possessed developed wings that probably allowed it to fly for short distances.  Sandstone monoliths, dubbed the Temple of the Sun and the Temple of the Moon, tower over the desert flats of Utah's Capitol Reef National Park. These formations were sculpted from sandstone deposited here in the Jurassic period about 160 million years ago.  Domelike mogotes in Valle de Vi�ales National Park, Cuba, emerge from a blanket of fog. These geologic formations date to the Mesozoic era, when layers of sedimentary limestone accumulated under water. Over time, acidic chemicals, along with wind and water erosion, molded these limestone remnants into mogotes.  Clinging to life on an offshore crag, a tuatara looks little different from his Jurassic relatives. Today, like many species, this living fossil carries out a threatened existence in New Zealand. untung gwe g hidup di jaman Dinosaurus..../heh |
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