osteostracan การใช้

*" A New Osteostracan Fauna from the Devonian of the Welsh Borderlands and Observations on the Taxonomy and Growth of Osteostraci"
Most osteostracans had a massive cephalothorac shield, but all Middle and Late Devonian species appear to have had a reduced, thinner, and often micromeric dermal skeleton.
Most of the ostracoderms, such as thelodonts, osteostracans, and galeaspids, were more closely related to the gnathostomes than to the surviving agnathans, known as cyclostomes.
Almost nothing is known of the rest of the body, save that it had a pair of well-developed pectoral fins, similar to osteostracans and gnathostome fish.
Classes of vertebrates listed in chronological order from oldest to most recent include heterostracans, osteostracans, coelolepid agnathans, acanthodians, osteichthyan fishes, chondrichthyan fishes, amphibians, reptiles, mammals, and birds.