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题目材料：
Many paleontologists have linked the origin of the vertebrate skeleton to the need for defense. According to this hypothesis, the first, soft-bodied vertebrates, living in the seas of the Cambrian period, began to evolve extensive coverings of bony scales or plates as the result of predation by numerous invertebrate carnivores. Teeth are thought to have been secondary features evolved over millions of years from those plates that had migrated to the mouth. Another hypothesis, however, contends that many of the definitive characteristics of vertebrates, such as paired eyes, would not have evolved unless the first vertebrates were predatory.
Tiny, spiky Cambrian fossils from small, eel-like animals known as conodonts have important implications for this debate. It has been shown that these fossils are teeth from the mouths of conodonts, which may have been among the earliest vertebrates and which otherwise lacked any mineralized skeleton. If teeth are more primitive than external plates, then the vertebrate skeleton may have evolved from adaptations to facilitate predation rather than from adaptations to facilitate protection.
Tiny, spiky Cambrian fossils from small, eel-like animals known as conodonts have important implications for this debate. It has been shown that these fossils are teeth from the mouths of conodonts, which may have been among the earliest vertebrates and which otherwise lacked any mineralized skeleton. If teeth are more primitive than external plates, then the vertebrate skeleton may have evolved from adaptations to facilitate predation rather than from adaptations to facilitate protection.
以上解析由 考满分老师提供。
