Although it is the defining organ of the Chordata, the notochord and its cells are one of the least understood vertebrate organs. This may be because large part

"Although it is the defining organ of Chordates, the notochord is perhaps the least understood of vertebrate organs because it is usually considered a transient

Animal life, now and over the past half billion years, is incredibly diverse. Describing and understanding the evolution of this diversity of body plans - from

Chordate Origins and Evolution: The Molecular Evolutionary Road to Vertebrates focuses on echinoderms (starfish, sea urchins, and others), hemichordates (acorn