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This nOde last updated November 27th, 2004 and is permanently morphing...
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dinosaur (dì´ne-sôr´) noun
1.Any of various extinct, often gigantic, carnivorous or herbivorous reptiles of the orders Saurischia and Ornithischia that were chiefly terrestrial and existed during the Mesozoic era.
2.A relic of the past: "living dinosaurs of the world of vegetation" (John Olmsted).
3.One that is hopelessly outmoded or unwieldy: "The old, big-city teaching hospital is a dinosaur" (Peggy Breault).
[Greek deinos, monstrous +
Greek sauros, lizard.]
- di´nosau´ric (-sôr´îk) adjective
Dinosaur, any of a group of extinct reptiles that lived from about 230 million years ago to about 65 million years ago. Dinosaurs flourished during the Mesozoic Era, which is divided into three periods, including the Triassic, the Jurassic, and the Cretaceous. Dinosaurs are classified into two orders according to differences in pelvic structure: Saurischia, or lizard-hipped dinosaurs, and Ornithischia, or bird-hipped dinosaurs.
Dinosaur ancestors were called archosaurs. Some archosaurs developed a bipedal (two-legged) posture and S-shaped necks, and it was some species of these that eventually evolved into dinosaurs. The earliest dinosaurs were about 0.5 m (about 1.6 ft) long. By about 175 million years ago, most of the basic varieties of dinosaurs had appeared.
The environment during the dinosaurian era was far different than today's environment. The days were several minutes shorter, and the sun'sradiation was weaker. Carbon dioxide, a gas that traps solar heat in the earth's atmosphere, was more abundant, causing warmer temperatures that kept polar ice caps from forming.
At the beginning of the dinosaurian era, the continents formed one supercontinent called Pangaea, and the oceans formed one vast ocean called Panthalassa. Eventually, movements of the earth's crust separated Pangaea into northern and southern continental blocks, and the modern continents appeared by the end of the dinosaurian era.
Behavior and Physiology
The behavior of dinosaurs was governed by their metabolism and by their central nervous system. It is unclear whether dinosaurs were purely endothermic (warm-blooded), like modern mammals, or ectothermic (cold-blooded), like modern reptiles. By determining whether they were warm- or cold-blooded, paleontologists could discover whether dinosaurs behaved more like modern mammals or more like modern reptiles. Endotherms control their body temperature internally by means of their metabolism, resulting in higher activity levels and energy needs than ectotherms. Ectotherms have a slower metabolism and control their body temperature by using the temperature of their surroundings to warm up or cool down.
Dinosaurs' anatomy changed gradually as they evolved. Because they grew smaller throughout the latter half of the dinosaurian era, they had to become more active and develop higher metabolisms to stay warm. Smaller animals lose heat more quickly than large ones. Their teeth became larger, their breathing passages became separate from their mouth cavity, and their nostrils became larger. These changes may have helped the dinosaurs digest their food and change it into energy more quickly and efficiently, helping them maintain a higher metabolism.
The central nervous system of dinosaurs affected their behavioral flexibility- how much they could adapt their behavior to deal with changing situations. Scientists believe that the ratio of dinosaurs' brain size to their body weight increased as the animals evolved, resulting in greater behavioral flexibility.
Saurischian dinosaurs had a primitive pelvis with a single bone projecting down and back from each side of the hips. There were three main kinds of saurischians: theropods, prosauropods, and sauropods.
Most theropods were bipedal
flesh-eaters. Large theropods, such as Tyrannosaurus rex, had jaws and
teeth adapted to tearing prey apart. Theropods called raptors had
powerful claws on their hands and feet and used their flexible tails
Prosauropods, with small skulls and long, slender necks, were bipedal and browsed on bushes and trees. During the late Triassic and early Jurassic periods, prosauropods were the largest plant-eating dinosaurs.
Sauropods descended from prosauropods. By the middle of the Jurassic Period they far surpassed all other dinosaurs in size and weight, reaching lengths of more than 25 m (more than 82 ft) and weights of about 90 metric tons. They walked on four pillarlike legs and had a small skull in proportion to their body.
Ornithischians had a pelvis with a two-boned structure projecting down and back from each side of the hips, apparently like the hips of birds. There were five kinds of ornithischians: stegosaurs, ankylosaurs, ornithopods, pachycephalosaurs, and ceratopsians.
Stegosaurs were quadrupedal (four-legged), had various kinds of body armor, and resembled gigantic porcupines. The Stegosaurus bore a double row of triangular bony plates along its back.
During the Cretaceous Period, ankylosaurs replaced stegosaurs. Looking like giant horned toads, they had heavy bony rings and spines on their necks, and some had a bony plate in each eyelid.
Ornithopods, also called duck-billed dinosaurs, became the most abundant plant-eating dinosaurs during the Cretaceous period, probably migrating in herds of thousands. They ranged in size from 2 m (6 ft) long to 10 m (32 ft) long and weighed from 15 kg (33 lb) to 4 metric tons.
Pachycephalosaurs were small
bipeds with thickened skulls, flattened bodies, and bony tails. Many,
such as the Pachycephalosaurus, had a skull capped by a rounded dome
of solid bone, perhaps for butting.
The quadrupedal ceratopsians, including Triceratops, usually had horns over the nose and eyes and a saddle-shaped bony frill extending from the skull over the neck. They may have lived in herds.
According to one theory, dinosaurs were slowly driven to extinction as the environment changed when shallow seas withdrew from the continents. Supporters of this theory believe that the extinction of dinosaurs took place over several million years.
An opposing theory holds that an asteroid or comet crashed into the earth and caused catastrophic destruction of the environment, leading to the extinction of the dinosaurs. Scientists have discovered in Mexico a buried impact crater (thought to be from a large comet striking the earth) that is 200 km (124 mi) in diameter. They have found that the impact and the dinosaur extinction occurred nearly simultaneously.
Dinosaur bones provide clues about how these animals interacted with each other and reveal information about body form, weight, and posture. Various features of the bones provide information on muscles, growth rates, and the brain. Fossilized contents of abdomens provide clues to diet.
loser: has-been, dinosaur, extinct volcano
Three feet in la brea tar
Extinction never felt so good
when i was in kindergarten i used to trace dinosaurs nonstop. i was completely obsessed with taking any and all drawings of extinct reptiles and tracing them on tracing paper. to this day i do not know why i had this obsession. it seems very symbolic.
another thing coming into light is the idea that dinosaurs could have had feathers. we only have bones to go by, so we have no idea what these creatures smelled like, tasted like, or sounded like. for all we know they could have had bright orange polkadot skin... the only remnants of dinos these days are crocs, komodo dragons, and the bit of scale on the claws of birds. i'm intrigued by the idea that these giant reptiles could have had feathers, even though most of them were never airborne. i believe there was a fossilized remains found in china recently that indeed preserved the notion of feathers on a small dinosaur.
the "feathered serpent" recurring archetype prevalent in almost all cultures, might also have a memetic trail....
- @Om* 11/6/01
Argentina unearths largest dinosaur
BY NIGEL HAWKES, SCIENCE EDITOR
BONES found in a desolate region of southern Patagonia have turned out to be from the largest dinosaur ever recorded.
The herbivore, which lived during the Cretaceous period 105 million years ago, appears to have been between 157ft and 167ft long - at least 26ft longer than the previous recordholder, Seismosaurus. The new creature, yet to be given a name, was found by a villager in a dusty region riddled with immense canyons called La Buitrera (The Vulture's Cage).
Carlos Muñoz, a palaeontologist and director of the Florentino Ameghino museum in southern Rio Negro province, said: "Two cervical vertebrae 3ft 10in high were found, in addition to a femur 6ft 6½in long and some other indicative bones." Like Seismosaurus, which was found in New Mexico, the new dinosaur had a small head, a long neck and an exceptionally long tail.
"We're ecstatic with this spectacular find. In Patagonia, walking among the rocks is enough to discover fossils," Señor Muñoz said.
The scrubby region has proved to be an extraordinary source of dinosaur fossils. Last April, Argentine palaeontologists uncovered the bones of a meat-eater thought to be bigger than Giganotosaurus, the biggest carnivore on record.
They also found the bulkiest herbivore, Argentinosaurus, which although not quite as long as Seismosaurus was more heavily built and probably weighed more than a hundred tons. A team of palaeontologists is working at La Buitrera discovery site with the aim of removing the cache of bones to the Florentino Ameghino museum for scrutiny by the end of the month.
"We are going to be working until January 31 and then we will take everything to the museum to remove the sediment, study it and later mount a presentation," Señor Muñoz said.
Dinosaurs have always impressed by their sheer bulk. An early record-holder was Brachiosaurus, found in 1907 in what is now Tanzania by a German expedition. Now in a Berlin Museum, Brachiosaurus is more than 74ft long. Its huge size has now easily been exceeded by the 120ft Argentinosaurus, the 130ft Seismosaurus, and now the unnamed Patagonian dinosaur, at 157ft to 167ft.
Together with its huge herbivore dinosaurs, Patagonia had flesh-eaters of matching bulk. Giganotosaurus, found by the Argentine palaeontologust Rodolfo Coria near Nuequen in 1993, dethroned Tyrannosaurus rex as the largest carnivorous dinosaur, only to be dethroned in its turn by last April's find, yet to be named.
Understanding how such huge creatures functioned remains a puzzle. The flesh-eaters must have been very small in number if they were not to run out of food, so any adverse event posed a distinct risk of wiping out the entire species.
The problem for the plant-eaters was different. The larger a creature's body is the more difficult it is to disperse body heat, assuming it is warm-blooded. The new Patagonian dinosaur must have run a risk of becoming so hot that it cooked.
For many years, the west of North America was the best place to find dinosaur fossils. Later, the Gobi Desert produced some wonderful finds. But in recent years, South America and particularly Argentina, Bolivia and southern Brazil, has been the prime area for dinosaur hunters. Lowell Dingus, a palaeontologist at the American Museum of Natural History in New York, said: "There's no question about it. This part of South America, especially Argentina, is producing more new and important discoveries than any other part of the world right now."
When the dinosaurs flourished, large parts of Patagonia were huge shallow freshwater lakes and floodplains, around which herds of the creatures gathered looking for food.
Floods laid down silty mud that preserved footprints and dinosaur bones, which are now coming to light as researchers begin to look closely at rocks of the right age to contain the fossils of dinosaurs. Dinosaur names are chosen by the scientists who first describe them, and generally try to convey something about the creature. The suffix -saurus, means lizard, and comes from the name first given to the creatures in 1841 by the anatomist Richard Owen, dinosaur - from the Greek deinos (terrible) and sauros (lizard).
Palaeontologists, however, are beginning to run out of superlatives for the ever-larger species they are finding. Supersaurus already exists, and so does Ultrasaurus.
Carlos Muñoz may be obliged to name his new fossil after the place where it was found.
Most people think it's far out if we get virtual reality up and running. This is much more profound than that. This is the real thing. We're going to find out what "being" is. It's a philosophical journey and the vehicles are not simply cultural but biology itself. We're closing distance with the most profound event that a planetary ecology can encounter, which is the freeing of life from the chrysalis of matter. And it's never happened before--I mean the dinosaurs didn't do this, nor did the procaryotes emerging. No. This takes a billion years of forward moving evolution to get to the place where information can detach itself from the material matrix and then look back on a cast-off mode of being as it rises into a higher dimension.
In his book, _The Dragons of Eden_, Carl Sagan proposed that one of the reasons that we seem to fear dragons is that our proto-human ancestors retained this fear of reptiles and dinosaurs in their DNA make-up. And this fear has been transmitted from one ancestor to another. Freud and Darwin also spoke of dragons and their impact on our dream states.
_Episode 23: Bart Gets Hit By A Car_ [Aired January 10, 1991] Season 2/Episode 10