heterocerc
/hɛtərˈɒsɛrk/Definitions
1. adjective
Having a heterocercal tail, a tail in which the upper lobe is larger than the lower lobe.
“The heterocercal tail of the shark is a distinctive feature.”
2. noun
A heterocercal tail, especially of a fish or shark.
“The fossil exhibited a well-preserved heterocerc.”