Parameter Tree:
EARTH SCIENCE > BIOLOGICAL CLASSIFICATION > ANIMALS/VERTEBRATES

 Definition:
Vertebrates are chordates with a backbone, either of cartilage or bone, and a
brain located inside a protective chamber of skull bones.

Reference:
Starr, C. and R.Taggart. 1998. Biology: the unity and diversity of life.
Wadsworth Publishing Company. Belmont, California.