What Does Evolution Have in Store?
Greetings. Fish, amphibians, reptiles, mammals, and birds (avian dinosaurs.) Complex forms of animal life. About 530 million years ago during the Cambrian explosion, fishlike animals with a notochord and eyes at the front of the body, such as Haikouichthys, begin to appear in the fossil record. By the late Cambrian, other jawless forms such as conodonts appear. During the Silurian, jawed and armoured fish appear on the scene, with giant placoderms such as Dunkleosteus, the cartilaginous Chondrichthyes, and the bony Osteichthyes. By the Devonian, fish diversity had greatly increased, including the placoderms, lobe-finned fishes, and early sharks, earning the Devonian the epithet "the age of fishes." The first major groups of amphibians developed in the Devonian period, approximately 370 million years ago, from lobe-finned fish which were similar in physical characteristics to the extant coelacanth and lungfish. These ancient lobe-finned fish had evolved multi-jointed leg-like...