Great white sharks are among the world's largest living predatory animals, and now we have a better idea of their ancestors and how these toothy media superstars evolved.
Great whites turn out not to be very related to the extinct
Carcharocles megalodon, the largest carnivorous shark that ever lived. Instead, they likely descended from broad-toothed
mako sharks.
As you can see from the above photo, however, these sharks back in the day had impressive mouths and teeth too. The well-preserved fossil from Peru is the only intact partial skull ever found
of a white shark that lived about 4.5 million years ago.
The species was named Carcharodon hubbelli for Gordon
Hubbell, who donated the fossil to the Florida Museum of Natural History
on the UF campus. The fossil jaw contains 222 teeth, some in rows up to
six teeth deep.
"The
impetus of this project was really the fact that Gordon Hubbell donated
a majority of his fossil shark collection to the Florida Museum," author
Dana Ehret, a lecturer
at Monmouth University in New Jersey who conducted research for the
study as a University of Florida graduate student, said in a press release."Naming the
shark in his honor is a small tip of the hat to all the great things he
has done to advance paleontology."
Ehret studying the fossil
He continued, "We
can look at white sharks today a little bit differently ecologically if
we know that they come from a mako shark ancestor."
That ancestor is 2 million years older than previously suspected, based on recalibrated dating.
Ehret said,"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."
He made the connection between modern great whites and C. hubbelli by comparing the physical shapes of shark teeth to one
another. While
modern white sharks have serrations on their teeth for consuming marine
mammals, mako sharks do not have serrations because they primarily feed
on fish. Hubbell's white shark has coarse serrations indicative of a
transition from broad-toothed mako sharks to
modern white sharks.
So the relatives of great whites used to eat more fish, but then switched to a more red meat diet consisting of mammal flesh.
The Pisco Formation in Peru where the shark fossil was found also includes new whale,
marine sloth and terrestrial vertebrate species. I look forward to hearing more about those finds in future.
This question also now remains: Did the great Carcharocles megalodon just die out, leaving behind no modern ancestors? For shark fans, hopefully not.
