Definition: The phylum that includes the vertebrates, defined by possession of: 1) a single dorsal nerve cord (the brain and spinal cord of mammals); 2) a cartilaginous rod, the notochord, which forms dorsal to the primitive gut in the early embryo, and is surrounded and replaced by the vertebral column in the subphylum vertebrata; and 3) by presence at some stage in development of gill slits in the pharynx or throat.
[L. chorda, fr. G. chorde, a string]
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Examples: glitazone, GI cocktail, etc.