Dinosaurs :: essays research papers

DinosaursDinosaur is the notice of large extinct reptiles of the Mesozoic Era,during which they were the preponderating land animals on Earth. The term wasproposed as a formal zoologic name in 1842 by the British anatomist Sir RichardOwen, in reference to large fogey bones unearthed in southern England. Thevarious kinds of dinosaurs are classified in two formal categories, the ordersSaurischia and Ornithischia, within the subclass Archosauria.The first recorded dinosaur cadaver prime consisted of a few dentition andbones. They were spy in 1882 in Sussex, England, by an English doctor,Gideon Mantell, who named them iguanodon. About the same time, other fossilteeth and bones were found near Oxford, England, by Rev. William Buckland.These were named Megalosaurus. Thousands of specimens energise since beendiscovered almost worldwide.Different types of dinosaurs varied greatly in form and size, and theywere adapted for divers(prenominal) habitats. Their means of survival can o nly beidentified from their fossil remains, and nearly identifications are in dispute.They ranged in weight from 4 to 6 lb., in the case of the compsognathus, and upto 160,000 lb., in the case of the brachiosaurus. Most dinosaurs were large, calculation more than 1,100 lb., and few weighed less than 100 lb. Most wereherbivores, but some saurischians were carnivorous. The majority were four-footed but some ornithischians and all carnivores walked on their hinder(prenominal) legs.Always classified as reptiles, dinosaurs defecate traditionally been assumedto have been reptilian in their physiology, cold-blooded, and ectothermic. Inrecent years several incompatible lines of evidence have been interpreted asindicating that dinosaurs may have had nimble blood and high rates of metabolism,comparable to birds and mammals. Evidence supporting this determine includes uprightposture and carriage mammallike microscopical structure of bones senselessfeatures suggestive of high activity an d specialized food-processing dentitionsand low ratios of dinosaurian predators to prey animals, two suggesting highfood requirements. The evidence is not conclusive--all the facts can be rather explained--but some dinosaurs may have been endothermic.The reproductive means of most dinosaurs is as yet unknown. Fossil eggs,attributed to one of the horned dinosaurs and a sauropod, have been discoveredin Mongolia and France. Fragments that are presumed to be of dinosaur eggs havealso been found in Brazil, Portugal, Tanzania, and in the United States,Colorado, Montana, and Utah. In Montana, Utah, and Alberta, Canada, fossils ofunhatched dinosaur eggs have been discovered. This evidence indicates egg-laying reproduction in dinosaurs, like most novel reptiles. A few scientistsbelieve that some dinosaurs may have given over birth to living young, but no