Chordata: Class Placodermi

The placoderms, an entirely extinct group of armored fishes, were the first jawed vertebrates. Jaws enabled vertebrates to become predators, an important factor in the later development of active, complex forms. The placoderms were also the first vertebrates to have the two pairs of lateral appendages (supported by pelvic and pectoral girdles) that characterized all later vertebrate groups. These primitive paired fins gave rise to the pelvic and pectoral fins of modern fishes and to the limbs of four-footed animals.

Sections in this article:

• Introduction
• Class Mammalia
• Class Aves
• Class Reptilia
• Class Amphibia
• Class Sacropterygii
• Class Actinopterygii
• Class Chondrichthyes
• Class Placodermi
• Classes Myxini and Hyperoartia
• Subphylum Vertebrata
• Subphylum Cephalochordata
• Subphylum Urochordata
• Bibliography

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