Presents the differentiating characteristics of the members of the phylum.

Details information on members of the phylum that do not have a spinal cord.

Lists the unique features of members of the phylum that it shares with what is believed to be its ancestors.

Features the unique characteristics of the members of the phylum. With links to classes and subgroups.

Relates phylum characteristics and information on subphyla.

Describes the common features of the members of the phylum as well as its major divisions. With links to subgroups.

Offers definitions, related topics, newspaper and magazine articles, and videos.

Cretaceous Fossils charts the existence of various representatives of the phylum through various eras.

Offers information on the phylum that includes humans and all the vertebrates. Includes distinguishing features.

Presents the unique characteristics of the animals with backbones. With links to related sites.

Contains characteristics, earliest fossil occurrence, and access to images of fossil specimens from various eras.

Presents a discussion on animal evolution throughout the eleven periods in this particular eon.

Shows pictures and links.

Lists web sites with short descriptions. With photos.

Shows pictures and links.

Provides access to a collection of images of members of the phylum.

Provides links to articles on members of the phylum.

Provides information on the group that includes the birds, mammals, reptiles, amphibians and fishes. With links to related sites.

Discusses member species and population. With pictures, links and related events.

Provides pictures and links to species in other areas of the globe.

Describes the group that includes the mammals, fishes, amphibians, reptiles and birds.

Offers access to images of skulls from mammals, reptiles and birds. With descriptions and measurements.

Offers scientific illustrations of members of the phylum.