Great Hammerhead - Taxonomy and Phylogeny

Taxonomy and Phylogeny

The great hammerhead was first described as Zygaena mokarran in 1837 by the German naturalist Eduard Rüppell. The name was later changed to the current Sphyrna mokarran. However, for many years the valid scientific name for the great hammerhead was thought to be Sphyrna tudes, which was coined in 1822 by Achille Valenciennes. In 1950, Enrico Tortonese determined that the specimens illustrated by Valenciennes were in fact smalleye hammerheads, to which the name S. tudes then applied. As the next most senior synonym, Sphyrna mokarran became the great hammerhead's valid name. The lectotype for this species is a 2.5 m (8.2 ft) long male from the Red Sea.

Phylogenetic analyses based on morphology, isozymes, and mitochondrial DNA show that the great hammerhead forms a clade with the smooth hammerhead (S. zygaena) and the scalloped hammerhead (S. lewini). These studies also reveal a close relationship with the winghead shark (Eusphyra blochii), and their position relative to the small hammerhead sharks (such as the bonnethead, S. tiburo) suggest that the first hammerheads to evolve had large rather than small cephalofoils.