The outer covering of the body composed of the SKIN and the skin appendages, which are the HAIR, the NAILS; and the SEBACEOUS GLANDS and the SWEAT GLANDS and their ducts.

The properties and relationships and biological processes that characterize the nature and function of the SKIN and its appendages.

Flat keratinous structures found on the skin surface of birds. Feathers are made partly of a hollow shaft fringed with barbs. They constitute the plumage.

The process of TOOTH formation. It is divided into several stages including: the dental lamina stage, the bud stage, the cap stage, and the bell stage. Odontogenesis includes the production of tooth enamel (AMELOGENESIS), dentin (DENTINOGENESIS), and dental cementum (CEMENTOGENESIS).

Remains, impressions, or traces of animals or plants of past geological times which have been preserved in the earth's crust.

Animals having a vertebral column, members of the phylum Chordata, subphylum Craniata comprising mammals, birds, reptiles, amphibians, and fishes.