A new fossil discovery has helped quell the 150-year-old debate over the origin of great white sharks, one of the largest living predatory animals and a magnet for media sensationalism.
Originally classified as a direct relative of megatooth sharks, researchers say they have new evidence pointing to the mako shark as the great white's ancestor.
University of Florida researchers have named and described an ancient intermediate form of the white shark, Carcharodon hubbelli, which shows the modern white shark likely descended from broad-toothed mako sharks.
The study deviates from the white shark's original classification as a relative of megatooth sharks such as the extinct Carcharocles megalodon, the largest carnivorous shark that ever lived.
Based on recalibrated dates of the excavation site in Peru, the study also concludes the new species was about 2 million years older than previously believed.
"We can look at white sharks today a little bit differently ecologically if we know that they come from a mako shark ancestor," said lead author Dana Ehret, a lecturer at Monmouth University in New Jersey who conducted research.
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"That 2-million-year pushback is pretty significant because in the evolutionary history of white sharks, that puts this species in a more appropriate time category to be ancestral or kind of an intermediate form of white shark."
Most ancient shark species are named using isolated teeth, but analysis of C hubbelli, also known as Hubbell's white shark, was based on a complete set of jaws with 222 teeth intact and 45 vertebrae.
The species was named for Gainesville resident Gordon Hubbell, a collector who recovered the fossils from a farmer who discovered them in the Pisco Formation of southern Peru in 1988. Hubbell donated the specimens to the Florida Museum of Natural History on the UF campus in December 2009.
Scientists extracted more accurate age estimates from mollusk shells in the fossil horizon to determine the shark species was from the late Miocene, about 6.5 million years ago, rather than the early Pliocene, about 4.5 million years ago.
The study was published in the journal Palaeontology.