Unlike the other aquatic species, we fear attack from sharks disproportionately to the actual risk, simply by virtue of the fact that some of them are large enough to mistake us for their prey under the right circumstances. Our characterization of sharks as ruthless killers intent on consuming us reflects our emotional response to the concept of being eaten alive than reality (Ellis, 1989)
According to many experts, one clue to this conclusion is the frequency of initial bite that is not followed up by a full-fledged attack. It seems that this is attributable to the fact that sharks tend to test potential prey before consuming it, partly, it is thought, to protect their teeth from unnecessary loss (Perrine, 1995)
Under the right circumstances, human beings simply find themselves within the vicinity of sharks looking to feed and our awkward swimming motion just happens to mimic some of the signals of distress or injury in the shark's natural prey (Stevens, 1999). In many cases, surfers fall victim to shark attack precisely because they violate some of the basic rules of shark safety: they swim at dawn and dusk, when sharks are most likely to feed, and they dangle their limbs from the sides of a flat board at the surface, despite the fact that sharks almost always attack from the and target prey that is approximately our size and our apparent shape, especially when we lie on the surface of the water with our limbs extended into the water (Ritter, 2000)
Contrary to assumption, sharks - even those large enough to consume us - do not actually hunt human beings. Under the right circumstances, human beings simply find themselves within the vicinity of sharks looking to feed and our awkward swimming motion just happens to mimic some of the signals of distress or injury in the shark's natural prey (Stevens, 1999)
However, biomechanical analysis suggests that arboreal, rather than cursorial flight is easier to evolve but evidence seems to prove otherwise. (Alexander; Vogel, 203); (Hill; Davis, The Origin and Early Evolution of Birds) Another model has been proposed by some biologists from the Oxford University
The most amazing feature was the presence of feathers, a unique characteristic of birds, on both sides of its tail bones. (Davies, Evolution) Later findings of bird-like dinosaurs in the early 1990's from Mongolia and Argentina gave credence to this theory
In fact, there are very few characters which can be used to distinguish theropods from the proto-birds. (Farlow; Brett-Surman; Walters, 215) Evolution of feathers and flight It has been suggested that the evolution of feathers was not a prerequisite for flight and might have evolved in dinosaurs for the purpose of display, camouflage or insulation
However, biomechanical analysis suggests that arboreal, rather than cursorial flight is easier to evolve but evidence seems to prove otherwise. (Alexander; Vogel, 203); (Hill; Davis, The Origin and Early Evolution of Birds) Another model has been proposed by some biologists from the Oxford University
These fossils have provided invaluable information about the evolution of feathers, wings and flight amongst theropods which eventually paved the way for the appearance of the modern birds. (Long; Schouten, 25); (Platt, New Feathered Dinosaur Found; Adds to Bird-Dino Theory) Alternative theories of bird origin Some other researchers like Chatterjee, Martin and Feduccia had suggested that birds did not evolve from dinosaurs but from crocodilians or ornithosuchids
Again, feathers might have served the process of insulation to the endothermic ancestors of birds. (Martin, 373) Skeletal similarities between dinosaurs and birds Early birds had a number of similarities with their immediate ancestors, the coelurosaurian dinosaurs (especially the Maniraptora including the Velociraptor) in terms of major skeletal structures
Subsequent discoveries of abundant and well-preserved fossils of dinosaurs as well as birds have offered extraordinary proof of the dinosaurian origin of birds, the beginnings of flight in birds and dinosaurs, and the origin of feathers before the beginning of flapping flight. (Zhou, 458); (Norell; Gaffney; Dingus, 11) Discussion: Brief history of dinosaurs It is believed that the dinosaurs first evolved during Late Triassic and included both herbivores as well as predators including four-toed and bipedal meaning bird-like predatory dinosaurs
However, very little evidence of birds was found from most of the Jurassic period and fossils like Archaeopteryx were found only from the end of the Jurassic period which was only 150 Myr back. (Paul, 5) The bipedal predators or theropods were obligatory bipeds
These fossils have provided invaluable information about the evolution of feathers, wings and flight amongst theropods which eventually paved the way for the appearance of the modern birds. (Long; Schouten, 25); (Platt, New Feathered Dinosaur Found; Adds to Bird-Dino Theory) Alternative theories of bird origin Some other researchers like Chatterjee, Martin and Feduccia had suggested that birds did not evolve from dinosaurs but from crocodilians or ornithosuchids
It is these coelurosaurs which eventually gave rise to birds by the end of the Jurassic period. (Sereno, 2141) The coelurosaurs comprised of both large and small-bodied theropods which had characteristic features in the limb bones, vertebrae and skull
It is these coelurosaurs which eventually gave rise to birds by the end of the Jurassic period. (Sereno, 2141) The coelurosaurs comprised of both large and small-bodied theropods which had characteristic features in the limb bones, vertebrae and skull
Studies of developing limbs of chicken, including a polydactylous variety and mouse have confirmed that the wing digits are actually 1, 2 and 3 and support the hypothesis of theropod descent of birds. (Vargas; Fallon, 87) Conclusion: The origin of birds from dinosaurs is a fascinating study
Subsequent discoveries of abundant and well-preserved fossils of dinosaurs as well as birds have offered extraordinary proof of the dinosaurian origin of birds, the beginnings of flight in birds and dinosaurs, and the origin of feathers before the beginning of flapping flight. (Zhou, 458); (Norell; Gaffney; Dingus, 11) Discussion: Brief history of dinosaurs It is believed that the dinosaurs first evolved during Late Triassic and included both herbivores as well as predators including four-toed and bipedal meaning bird-like predatory dinosaurs
1996), a nine-year-old boy's ear, ruthlessly bitten and torn by a Dalmatian, and the lives and limbs of other patients from 29 different countries have been reported as salvaged by slimy, ugly-looking and creepy leeches. The worms performed such feats by sucking gorged blood or blood clots in sufficient amounts for a few minutes or by letting blood ooze from its bite after sucking and preventing it from clotting, long enough for surgical procedures to be conducted, thus keeping the victim alive (Concannon 2000)