Chromatocytes are star-shaped cells derived from neural crest that produce pigments, and may be located either in the dermis or epidermis. Dense bone in the center of long bones would add little to their load-supporting ability, but would increase weight greatly. Compare the structure and function of a filoplume and a contour feather. A filoplume has a long, bare rachis with only a few barbs at the end, which do not have interlocking barbules. Filoplumes are found among contour feathers, and provide the bird with information about the position of contour feathers.
Contour feathers have a rachis and barbs with interlocking barbules to produce a semi-rigid vane.
The dermatocranium in fish is made up of a greater number of bones, more loosely connected to each other than in advanced vertebrates. Advanced vertebrates have reduced the number of bones in the dermatocranium, more rigidly fused the remaining bones together, and have developed modifications of the dermatocranium such as fenestra and secondary palates in many groups. Compare the structure and function of the splanchnocranium in a primitive, jawless vertebrate, and an advanced terrestrial vertebrate such as a mammal. In jawless vertebrates, the splanchnocranium is a series of similar arches, each made up of five hinged pieces, whose primary function is to support the gills. The skeleton of larger animals therefore is subjected to greater loading and stress than the skeleton of similarly shaped smaller animals.