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Dinosaurs: Their Rise & Fall

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Melody Stacker
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« Reply #255 on: August 09, 2009, 05:01:14 am »

In the years when the Deccan Traps theory was linked to a slower extinction, Luis Alvarez (who died in 1988) replied that paleontologists were being misled by sparse data. While his assertion was not initially well-received, later intensive field studies of fossil beds lent weight to his claim. Eventually, most paleontologists began to accept the idea that the mass extinctions at the end of the Cretaceous were largely or at least partly due to a massive Earth impact. However, even Walter Alvarez has acknowledged that there were other major changes on Earth even before the impact, such as a drop in sea level and massive volcanic eruptions that produced the Indian Deccan Traps, and these may have contributed to the extinctions.[123]
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« Reply #256 on: August 09, 2009, 05:01:46 am »

Failure to adapt to changing conditions

Lloyd et al. (2008) noted that, in the Mid Cretaceous, the flowering angiosperm plants became a major part of terrestrial ecosystems, which had previously been dominated by gymnosperms such as conifers. Dinosaur coprolites — fossilized dung — indicate that, while some ate angiosperms, most herbivorous dinosaurs mainly ate gymnosperms. Statistical analysis by Lloyd et al. concluded that, contrary to earlier studies, dinosaurs did not diversify very much in the Late Cretaceous. Lloyd et al. suggested that dinosaurs' failure to diversify as ecosystems were changing doomed them to extinction.[34]
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« Reply #257 on: August 09, 2009, 05:02:42 am »

Possible Paleocene survivors

Nonavian dinosaur remains are occasionally found above the K-T boundary. In 2002, paleontologists Zielinski and Budahn reported the discovery of a single hadrosaur leg bone fossil in the San Juan Basin, New Mexico and described it as evidence of Paleocene dinosaurs. The formation in which the bone was discovered has been dated to the early Paleocene epoch approximately 64.5 million years ago. If the bone was not re-deposited into that stratum by weathering action, it would provide evidence that some dinosaur populations may have survived at least a half million years into the Cenozoic Era.[124] Other evidence includes the finding of dinosaur remains in the Hell Creek Formation up to 1.3 meters (51 in) above (40000 years later than) the K-T boundary. Similar reports have come from other parts of the world, including China.[125] Many scientists, however, dismiss the "Paleocene dinosaurs" as re-worked, i.e. washed out of their original locations and then re-buried in much later sediments,[126][127] or find that, if correct, the presence of a handful of dinosaurs in the early Paleocene would not change the underlying facts of the extinction.[126]
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« Reply #258 on: August 09, 2009, 05:03:12 am »

History of discovery

Dinosaur fossils have been known for millennia, although their true nature was not recognized. The Chinese, whose modern word for dinosaur is konglong (恐龍, or "terrible dragon"), considered them to be dragon bones and documented them as such. For example, Hua Yang Guo Zhi, a book written by Zhang Qu during the Western Jin Dynasty, reported the discovery of dragon bones at Wucheng in Sichuan Province.[128] Villagers in central China have long unearthed fossilized "dragon bones" for use in traditional medicines, a practice that continues today.[129] In Europe, dinosaur fossils were generally believed to be the remains of giants and other creatures killed by the Great Flood.
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« Reply #259 on: August 09, 2009, 05:03:42 am »

Scholarly descriptions of what would now be recognized as dinosaur bones first appeared in the late 17th century in England. Part of a bone, now known to have been the femur of a Megalosaurus,[130] was recovered from a limestone quarry at Cornwell near Chipping Norton, Oxfordshire, England in 1676. The fragment was sent to Robert Plot, Professor of Chemistry at the University of Oxford and first curator of the Ashmolean Museum, who published a description in his Natural History of Oxfordshire in 1677. He correctly identified the bone as the lower extremity of the femur of a large animal, and recognized that it was too large to belong to any known species. He therefore concluded it to be the thigh bone of a giant human similar to those mentioned in the Bible. In 1699, Edward Lhuyd, a friend of Sir Isaac Newton, was responsible for the first published scientific treatment of what would now be recognized as a dinosaur when he described and named a sauropod tooth, "Rutellum implicatum"[131][132], that had been found in Caswell, near Witney, Oxfordshire.[133]
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« Reply #260 on: August 09, 2009, 05:04:06 am »

Between 1815 and 1824, the Rev William Buckland, a professor of geology at Oxford University, collected more fossilized bones of Megalosaurus and became the first person to describe a dinosaur in a scientific journal.[130][134] The second dinosaur genus to be identified, Iguanodon, was discovered in 1822 by Mary Ann Mantell - the wife of English geologist Gideon Mantell. Gideon Mantell recognized similarities between his fossils and the bones of modern iguanas. He published his findings in 1825.[135][136]
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« Reply #261 on: August 09, 2009, 05:04:24 am »

The study of these "great fossil lizards" soon became of great interest to European and American scientists, and in 1842 the English paleontologist Richard Owen coined the term "dinosaur". He recognized that the remains that had been found so far, Iguanodon, Megalosaurus and Hylaeosaurus, shared a number of distinctive features, and so decided to present them as a distinct taxonomic group. With the backing of Prince Albert of Saxe-Coburg-Gotha, the husband of Queen Victoria, Owen established the Natural History Museum in South Kensington, London, to display the national collection of dinosaur fossils and other biological and geological exhibits.
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« Reply #262 on: August 09, 2009, 05:04:50 am »

In 1858, the first known American dinosaur was discovered, in marl pits in the small town of Haddonfield, New Jersey (although fossils had been found before, their nature had not been correctly discerned). The creature was named Hadrosaurus foulkii. It was an extremely important find; Hadrosaurus was one of the first nearly complete dinosaur skeletons found and it was clearly a bipedal creature. (The first was in 1834, in Maidstone, Kent, England) This was a revolutionary discovery as, until that point, most scientists had believed dinosaurs walked on four feet, like other lizards. Foulke's discoveries sparked a wave of dinosaur mania in the United States.
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« Reply #263 on: August 09, 2009, 05:06:49 am »

Dinosaur mania was exemplified by the fierce rivalry between Edward Drinker Cope and Othniel Charles Marsh, both of whom raced to be the first to find new dinosaurs in what came to be known as the Bone Wars. The feud probably originated when Marsh publicly pointed out that Cope's reconstruction of an Elasmosaurus skeleton was flawed; Cope had inadvertently placed the plesiosaur's head at what should have been the animal's tail end.
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« Reply #264 on: August 09, 2009, 05:07:06 am »

The fight between the two scientists lasted for over 30 years, ending in 1897 when Cope died after spending his entire fortune on the dinosaur hunt. Marsh 'won' the contest primarily because he was better funded through a relationship with the US Geological Survey. Unfortunately, many valuable dinosaur specimens were damaged or destroyed due to the pair's rough methods; for example, their diggers often used dynamite to unearth bones (a method modern paleontologists would find appalling). Despite their unrefined methods, the contributions of Cope and Marsh to paleontology were vast; Marsh unearthed 86 new species of dinosaur and Cope discovered 56, for a total of 142 new species. Cope's collection is now at the American Museum of Natural History in New York, while Marsh's is on display at the Peabody Museum of Natural History at Yale University.[137]
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« Reply #265 on: August 09, 2009, 05:07:21 am »

Since 1897, the search for dinosaur fossils has extended to every continent, including Antarctica. The first Antarctic dinosaur to be discovered, the ankylosaurid Antarctopelta oliveroi, was found on Ross Island in 1986, although it was 1994 before an Antarctic species, the theropod Cryolophosaurus ellioti, was formally named and described in a scientific journal.

Current dinosaur "hot spots" include southern South America (especially Argentina) and China. China in particular has produced many exceptional feathered dinosaur specimens due to the unique geology of its dinosaur beds, as well as an ancient arid climate particularly conducive to fossilization.
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« Reply #266 on: August 09, 2009, 05:08:05 am »



William Buckland.
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« Reply #267 on: August 09, 2009, 05:08:44 am »



Othniel Charles Marsh, 19th century photograph.
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« Reply #268 on: August 09, 2009, 05:09:56 am »



Edward Drinker Cope, 19th century photograph
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« Reply #269 on: August 09, 2009, 05:11:08 am »

The "dinosaur renaissance"

The field of dinosaur research has enjoyed a surge in activity that began in the 1970s and is ongoing. This was triggered, in part, by John Ostrom's discovery of Deinonychus, an active predator that may have been warm-blooded, in marked contrast to the then-prevailing image of dinosaurs as sluggish and cold-blooded. Vertebrate paleontology has become a global science. Major new dinosaur discoveries have been made by paleontologists working in previously unexploited regions, including India, South America, Madagascar, Antarctica, and most significantly in China (the amazingly well-preserved feathered dinosaurs in China have further consolidated the link between dinosaurs and their conjectured living descendants, modern birds). The widespread application of cladistics, which rigorously analyzes the relationships between biological organisms, has also proved tremendously useful in classifying dinosaurs. Cladistic analysis, among other modern techniques, helps to compensate for an often incomplete and fragmentary fossil record.
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