生命经过三十多亿年的进化，到三亿七千万年前，江口温暖的水域已经生活着多种多样的鱼和鱼形动物，这是它们繁盛的时期。科学家为我们绘制了精彩的复原图画，在图上离我们最近的位置，一群原始的鱼类正在被一条鳍鱼追逐，它也许是陆生动物的远祖。在图片的左上方，一条早期肺鱼正浮向水面以获得新鲜的空气，它们的后代现在依然在非洲自由生活。在河底，两条盾皮鱼正在刮取食物。在右侧的河底，一条装甲的无颌鱼形动物正在享受它们最后的时光，它们看起来确实很像鱼类，但它们没有可以自由开合的口。它旁边的远处，另一条鳍鱼正准备离开这个危险的地方。 This scene depicts a muddy estuary that occupied what is now southern Quebec, about 370 million years ago. On the left, a group of Cheirolepis (primitive ray-finned fishes) is being followed by Eusthenopteron, a large lobe-finned relative of the tetrapods seen in the center. In the upper left, an early lungfish called Scaumenacia rises to the surface in order to gulp air. In the lower center, box-like armored placoderms belonging to the genus Bothriolepis cruise slowly over the muddy bottom in order to feed on detritus. One of the last armored jawless fishes, Alaspis (an ostracoderm related to Cephalaspis), is also feeding on bottom detritus, at the lower right. To the far right is the fish Elpistostege, an extinct relative of tetrapods.(words from amnh.org)