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  3. A massive dinosaur hatchery containing thousands of fossilized eggs and doze

A massive dinosaur hatchery containing thousands of fossilized eggs and doze

游客2024-08-08  64
问题     A massive dinosaur hatchery containing thousands of fossilized eggs and dozens of embryos has been discovered in the Patagonia region of Argentina, a find that should give researchers their first insight into the embryonic development of these fascinating animals.

    The eggs were laid by sauropods-placid, plant-eating dinosaurs with long necks and tails and a small head-over an area of at least a square mile along ancient stream beds, an American and Argentine team said at a news conference in Washington, DC.
    The find represents the first embryonic fossils containing remnants of skin, the first sauropod embryos and the first dinosaur embryos found in the Southern Hemisphere.
    Perhaps more importantly, the deposit contains embryos with a broad cross-section of gestational ages and should thus provide paleontologists with their first good look at how the creatures developed during their early stages of life.
    "There are more than 200 sites around the world with fossils of dinosaur eggs, but only a half-dozen that contain embryos," said paleontologist Philip Currie of the Royal Tyrrell Museum in Alberta. "And these are the most spectacular embryos ever found. "
    The team members literally stumbled across the specimens. On the second day of their expedition last year, they found the site, which was littered with fossils of egg shells. "You couldn’t take a step without walking on shell fragments," said Luis M. Chiappe, of the American Museum of Natural History in New York City, co-leader of the expedition.
    The team named the site Auca Mahuevo for its tremendous abundance of eggs ( huevos in Spanish). The eggs were round, about 5 to 6 inches in diameter. Had they hatched, the baby dinosaurs inside would have started life a mere 15 inches long, but grown to a length of 45 feet.
    Many of the eggs contained not only fossils of the bones of the embryonic dinosaurs, but also fossils of skin fragments. "That is remarkable because the skin is such a delicate structure and is very rarely preserved in fossil form," Chiappe said. "The skin of a dinosaur embryo has never been discovered before. "
    Because the team has discovered specimens of different gestational ages, researchers will be able to chart the growth of the embryos within the eggs, measuring the growth rate of bones, for example, and the order in which various organs formed.
    "We can know the pattern of development of dinosaurs that lived millions of years ago and compare it to modern reptiles," Chiappe said.  " That has not been possible with any other dinosaurs. " The team does not know yet precisely which type of sauropod dinosaur produced the eggs, but the discovery of tiny teeth in some eggs provides an intriguing clue. One embryo alone has at least 32 individual, pencil-shaped teeth, each small enough to fit easily into the capital "O" at the beginning of this sentence.
    The only sauropod dinosaurs with teeth this shape that were alive during the period when the fossils were formed were titanosaurs. The remains of titanosaurs are common near Auca Mahuevo, making it very likely that the embryos belong to this group. [br] What makes it likely that the newly found embryos belong to the group of titanosaurs?
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答案 The tiny teeth found in some eggs
解析 (文章倒数第二段第三句提到在某些蛋中发现了一些微小的牙齿，最后一段提到同一时期具有此形状牙齿的sauropod恐龙只有titanosaurs。因此将新发现的胚胎归类为titanosaurs的原因是在蛋中发现了微小的牙齿。)
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