Chordata: Class Placodermi

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

See more Encyclopedia articles on: Vertebrate Zoology