Definitions for "Heterocercal"
Keywords:  lobe, vertebral, caudal, shark, tail
Having the vertebral column evidently continued into the upper lobe of the tail, which is usually longer than the lower one, as in sharks.
The caudal fin is heterocercal if the vertebral column extends up into the dorsal lobe. The fin is often asymmetrical. When the base of caudal fin is not at right angles to the body it usually heterocercal.
unequally lobed; said of the tail or caudal fin of a fish where the upper lobe is larger than the lower, and in which the last few vertebrae or the vertebral column are bent upward