Hammerhead Shark - Taxonomy

Taxonomy

Since sharks do not have mineralized bones and rarely fossilize, it is their teeth alone that are commonly found as fossils. The hammerheads seem closely related to the carcharhinid sharks. The teeth of hammerheads resemble those of some carcharhinid. Using mitochondrial DNA, Andrew Martin constructed a phylogenetic tree of the hammerhead sharks that showed the winghead shark as its most basal member. As the winghead shark has proportionately the largest "hammer" of the hammerhead sharks, this suggests that the first ancestral hammerhead sharks also had large hammers.