托福阅读自然科学类文章之The Origination of Birds-智课教育旗下智课教育.pdfVIP

智 课 网 托 福 备 考 资 料 托福阅读自然科学类文章之The Origination of Birds-智课教育旗下智课教育 自然学科是托福阅读文章题材中比较常见的类型，本文和大家分享 的是自然科学类文章汇总系列的内容，供考生参考使用，希望考生能够 认真备考，预祝考生能够考出好成绩。 自然学科是托福阅读文章题材中比较常见的类型，本系列为大家汇 总整理了多篇托福阅读自然科学类文章，大家在托福备考时可以有针对 性的进行复习，本篇为大家带来的是The Origination of Birds，并附有相应的练习，希望大家都能顺利拿下托福阅读 高分。 The Origination of Birds Keywords:pterosaurs, Birds, wing, flight, fossil The first flying vertebrates were true reptiles in which one of the fingers of the front limbs became very elongated, providing support for a flap of stretched skin that served as a wing. These were the pterosaurs, literally the winged lizards. The earliest erosaurs arose near the end of the Triassic period of the Mesozoic Era, some70 million years before the first known fossils of true birds occur, and they presumably dominated the skies until they were eventually displaced by birds. Like the dinosaurs, some of the pterosaurs became gigantic; the largest fossil discovered is of an individual that had a wingspan of 50 feet or more, larger than many airplanes. These flying reptiles had large, tooth-filled jaws, but their bodies were small and probably without the necessary powerful muscles for sustained wing movement. They must have been expert gliders, not skillful fliers, relying on wind power for their locomotion. Birds, despite sharing common reptilian ancestors with pterosaurs, evolved quite separately and have been much more successful in their dominance of the air. They are an example of a common theme in evolution, the more or less parallel development of different types of body structure and function for the same reasonin this case,for flight. Although the fossil record, as always, is not complete enough to determine definitively the evolutionary lineage of the birds or in as much detail as one would like, it is better in this case than for many other animal groups. That is because of the unusual preservation in