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阅读机经中恐龙冷热血题目 我考了下古 机经大概是这么说 一个讲两个科学家D，O关于恐龙是冷血动物还是热血动物的课题， 科学家D说恐龙温血是由A造成的好像是metabolic，他们的体温和新陈代谢有关。恐龙的xx导致了什么纤维组织的xx...讲到了血管啊，什么carnal(记不得具体的单词了） 说只有新陈代谢快的动物才能发展演化到这样复杂的carnal~~就是这个意思，说恐龙是热血动物。 O然后也做了一些实验，说D的实验结果不正确。另一个科学家O来说不对。他做了个实验，把冷血动物和热血动物的carnal分别置于两种情况下
（1）carnal 的活动比较active (2)carnal 的活动不active 发现carnal 活动active的，不管是冷血还是热血都能演化到这样的复杂程度 所以得出结论说是carnal 活动的active 导致了-----复杂的carnal器官的演化，而不是新陈代谢的快慢 然后我就去百度 恐龙生态学 查得那个所谓的carnal 其实是叫haversian canals 然后两个科学家 分别是de Ricqles 和 Owerkowicz 前者是恐龙温血倡导者 后者是冷血的倡导者 然后搜了网上关于这两人的文章 结合了好几篇 把两人的实验总结成几段放上来 盼机经作者能够上来看看 看文章是不是大概说了类似的内容（肯定不是原文了 因为我本来就是东拼西凑的） 只是看看内容有没有相似度 还有能不能回忆起一些来~ 真是多谢了~~ 感恩。。。 Armand de Ricqles, a paleontologist and anatomist at the University of Paris who claimed that he could tell the difference between endothermic and ectothermic animals by putting their bones under a microscope. Here, at last, seemed to be a concrete method for resolving the debate. When De Ricqles looked at tissue- thin slices of dinosaur bone, he found striking similarities to the bone of birds and mammals. In young warm-blooded animals today, fast-growing bone invades connective tissue so quickly that it traps the fibers and blood vessels already there in a dense, intricate weave. As that bone matures, channels known as haversian canals appear, in which specialized cells destroy old bone and replace it with new material. De Ricqles argued that the texture of the bone and the presence of the canals could be used to deduce that an animal's skeleton was growing quickly. And since fast growth naturally required a high metabolic rate to fuel it, such an animal had to be endothermic. The evidence based on bone structures has come under fire too. Tomasz Owerkowicz, a young Harvard University red searcher, has asserted that the dense canals that de Ricqles detected could have resulted from physical exertion rather than endothermy. In an ingenious experiment, Owerkowicz gave. cold-blooded monitor lizards regular treadmill workouts and then compared their bones with those of nonaerobicized contemporaries. The well-exercised group showed the same kind of complex channels characteristic of mammals, birds, and dinosaurs, suggesting that Haversian canals a causally linked to an active lifestyle rather the warm bloodedness. The only clear distinction he could draw, in fact, was between the exercised and unexercised animals.The ones that ran on a treadmill had bones packed with haversian canals--regardless of whether they were warm- blooded or cold. "What that means," says Owerkowicz, "is that an animal's thermal physiology doesn't shape a bone's microstructure. But exercise does." When an animal exercises, he points out, its bones are strained and stressed. Since they are made of an elastic material, they can generally withstand these forces, but occasionally they yield to fatigue and form a tiny stress fracture. "That relieves the strain, but if the loading continues, it can lead to a full fracture," says Owerkowicz. "The bone needs to remove that microcrack and put new bone in its place. This is the role of remodeling. Bone that is dense with haversian canals, therefore, tells you that the animal was active." What it doesn't tell you is the animal's resting metabolic rate or its body temperature--in other words, whether it was warm- or cold-blooded. 附：机经作者提到的关于此题的题目 | 
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发表于 2009-3-26 07:28:00
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