生物生生不息,脊椎动物是由无脊椎动物演化而来。最早的脊椎动物化石是什么?是一种无颌的“鱼”类,一般称无颌类,或叫圆口类。它们是包括人类在内的脊椎动物发展演化的初期生物。无颌类—鱼类—两栖类—爬行类—鸟类—哺乳类—人类,这就是脊椎动物的演化进程。在生物分类学上,无颌“鱼” Living creatures, vertebrates are evolved from invertebrates. What is the earliest vertebrate fossil? Is a jawless “fish ” class, generally called jaw type, or called round mouth class. They are the initial creatures of the evolution of vertebrates, including humans. No jaw class - fish - amphibians - reptiles - birds - mammals - humans, which is the evolution of vertebrates. In taxonomy, jaw-free “fish”