Acanthodians later appeared after the Ostracoderms. Their fins were distinctive because of the lack of rays, and the same small membranes of skin were covered with the same scales that cover its body. Acanthodians were no longer than 25 cms, and they developed a lifestyle of active swimming, and a sufficient sense of sight. (miguasha.ca) The Acanthodian’s jaw wasn’t primarily similar to the sharks, but most have Later, another fish evolved into Placoderms, which were seen as a fish with teeth in the Devonian period. Most placoderms were bottom dwellers, roaming in the deep areas. They lived from the subliminal to the Devonian period. Placoderms like the Dunkleosteus were the first super predator vertebrae that preyed on other fish. These
