阅读理解 A 作业 3 When Archaeopteryx , a feathered skeleton that was seeminglyhalf dinosaur and half bird, turned up in 1862—three years after thepublication of “The Origin of Species”—the origin of birds became a subject ofraging debate among palaeontologists. Suggestions that they were the directdescendants of theropod dinosaurs (a group of bipedal meat-eaters that include Allosaurus , Velociraptor and Tyrannosaurus ) caused quite a flap. Today, mostresearchers agree that birds are, indeed, a branch of the Dinosauria. How theymade the transition from the land to the sky, though, has yet to be agreed. Buta paper in this week's Current Biology , by Christopher Glen and Michael Bennettof the University of Queensland, makes a strong case that they did it by jumping. Consideringthe diversity of life on Earth, flight is surprisingly rare. It has evolvedonly four times: among the insects about 300m years ago, the pterosaurs (230m),the birds (150m) and the bats (50m). That suggests it is a hard trick to pull off.For birds, there is general agreement that feathers came before flight. Fossilsfrom north-eastern China show animals that had feathers but clearly could nothave flown, as well as ones that look like proper birds. The best guesses arethat feathers evolved either for insulation (as fur did in mammals) or fordisplay, and that natural selection took advantage by turning them into a meansof transport. Thereare two broad schools of thought about what happened next. One argues thatbirds' immediate ancestors lived in trees. Members of this school think thatpowered flight developed as a natural extension of gliding (such controlledfalling is used as a way of travelling from tree to tree by several arborealspecies today). Gliding itself developed because of the lift provided byfeathered forearms. Thealternative is that flight evolved on the ground. Some researchers who belongto this school of thought suggest that the power provided by flapping protowingsmay have given their owners an edge in the pursuit of prey. Others hypothesisethat feathery forearms helped animals steer and stabilise themselves. Unfortunately,behaviour does not fossilise, so it looked as though the question might neverbe answered. But Dr Glen, a palaeobiologist, and Dr Bennett, a biomechanic, thinkthey have worked out how to do so. Their crucial observation is that in modernbirds the curvature of the third toe (which carries a lot of weight duringwalking and climbing) varies with species' lifestyles. Birds that spend lots oftime climbing around on the trunks of trees have dramatically curved thirdtoes. Those that hop around on branches have mildly curved ones. Those thatforage mainly on the ground have the least curved of all. The two researchers compared these observations with their findings forthe bird-like dinosaurs and dinosaur-like birds of China. They noticed that thetoes of both feathered dinosaurs and of the earliest flying birds were similarto those of modern birds that spend most of their time on the ground. Flight,in other words, came before birds took to the trees. They are not fallenangels, but risen reptiles. 1.Which one of the following statements is NOT true of the current debate on theorigin of birds? [A]The opinion that birds were the direct descendants of dinosaurs gives the worlda shock. [B]Palaeontologists have get consensus on the specie’s transition from the land to the sky. [C]Palaeontologists have different opinions on the process of the transition. [D]The paper in this week's Current Biology demostrate that the specie movedby hopping before they flied. 2.The reason why flight is surprisingly rare is that _____ [A]life on earth is diversified. [B]many species of this kind were eliminated during evolution. [C]feathers evolved not for a means of transport. [D]it is very hard to have such evolution. 3.Thetwo schools of thought have different opinions on _____ [A]the functions of feathered forearams in transition from ground to sky. [B]the location of living place before the animals’ evolutionto birds. [C]the development of powered flight. [D]the power provided by either gliding or flapping. 4.The conclusion of the study carried out by Dr. Glen and Dr. Bennet is that_____ [A]powered flight developed as feathered forearms provided lift. [B]flight evolved on the ground before they descend onthe trees. [C] earliest birdsshare similar toes with their modern counterparts. [D] earliestflying birds evovled from feathered dinosaurs. 5.Whichone of the following statements is NOT true of opinions of Dr. Glen and Dr.Bennet? [A]Birdsrealized the transition from reptile to flight by jumping. [B]Dinasaurs are, as a matter of fact, the direct ancester of birds. [C]Feathersevolves not for the purpose of flight. [D] Bird’s behaviors is indeed fossilised bytheir various shape of the third toe. 阅读理解A作业3.docx