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  3. 　 　 The first birds appeared during late Jurassic times. These birds are know

　 　 The first birds appeared during late Jurassic times. These birds are know

游客2024-01-05  24
问题 　 　    The first birds appeared during late Jurassic times. These birds are known from
　 　four very good skeletons, two incomplete skeletons, and an isolated feather, all from
　 　the Solnhofen limestone of Bavaria, Germany. This fine-grained rock, which is
　 　extensively quarried for lithographic stone, was evidently deposited in a shallow
(5)  coral lagoon of a tropical sea, and flying vertebrates occasionally fell into the water
　 　and were buried by the fine limy mud, to be preserved with remarkable detail In this
　 　way, the late Jurassic bird skeletons, which have been named Archaeopteryx, were
　 　fossilized. And not only were the bones preserved in these skeletons, but so also
　 　were imprints of the feathers. If the indications of feathers had not been preserved in
(10) association with Archaeopteryx, it is likely that these fossils would have been
　 　classified among the dinosaurs, for they show numerous theropod characteristics.
　 　Archaeopteryx were animals about the size of a crow, with an archeosaurian type of
　 　skull, a long neck, a compact body balanced on a pair of strong hind limbs, and a
　 　long tail. The forelimbs were enlarged and obviously functioned as wings.
(15) Modern birds, who are the descendants of these early birds, are highly
　 　organized animals, with a constant body temperature and a very high rate of
　 　metabolism. In addition, they are remarkable for having evolved extraordinarily
　 　complex behavior patterns such as those of nesting and song, and the habit among
　 　many species of making long migrations from one continent to another and back
(20) each year. Most birds also have very strong legs, which allows them to run or walk on the
　 　ground as well as to fly in the air. Indeed, some of the waterbirds, such as ducks and
　 　geese, have the distinction of being able to move around proficiently in the water, on
　 　land, and in the air, a range in natural locomotor ability that has never been attained
(25) by any other vertebrate.
选项 A、nesting materials
B、four skeletons in good condition
C、two fragmented skeletons
D、a single feather
答案 A
解析
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