Evolution
A
new prehistoric shark species has revealed a great deal more about the
evolution of white sharks, helping to quell a 150 year old debate.
Previously, researchers had been unsure whether white sharks evolved
from smaller mako sharks or from megatooth sharks (of which the largest
carnivorous shark ever known, Megalodon, was a member). The idea that
mako sharks are white shark ancestors has gaine
d
considerable support from this extremely well-preserved new species -
often with shark fossils only isolated teeth are found, but in this case
we have a complete set of jaws (with 222 teeth) and 45 vertebrae.
The teeth of this fossil shark, named Carcharodon hubbelli, show both
white and mako shark characteristics. They have a white shark-like shape
and similar coarse serrations, but they also have features of mako
sharks (such as the third anterior tooth being curved out). It certainly
seems to be a gradation between the broad-toothed makos and today's
white sharks.
These characteristics had been spotted when the
fossil was first found, but its age had been estimated inaccurately at
4.5 million years old - too late to be a white shark ancestor. After
researchers revisited the dig site and found mollusc shells, they
calculated its true age as 6.5 million years old. This new age put C.
hubbelli at the appropriate time to be a white shark ancestor.
Though this supports the mako ancestor theory, team leader Dana Ehret
(Monmouth University, New Jersey) is not so sure we've heard the last of
megatooth ancestry. "Some people might jump to the conclusion that this
is a smoking gun, that the debate is over," Ehret said. "I don't think
the debate will be over... While I personally think we make a very
strong case that white sharks evolved from mako shark ancestors, I know
some people out there will continue to investigate the relationships
between the giant shark Megaladon and modern white sharks. That's how
science has to work: You have to put out hypotheses and also test them,
see if they stand up to scientific research."
Photo credit: Florida Museum of Natural History photo by Jeff Gage.
http://www.bbc.co.uk/news/
http://www.sciencedaily.com/
http://www.livescience.com/
A
new prehistoric shark species has revealed a great deal more about the
evolution of white sharks, helping to quell a 150 year old debate.
Previously, researchers had been unsure whether white sharks evolved from smaller mako sharks or from megatooth sharks (of which the largest carnivorous shark ever known, Megalodon, was a member). The idea that mako sharks are white shark ancestors has gaine
Previously, researchers had been unsure whether white sharks evolved from smaller mako sharks or from megatooth sharks (of which the largest carnivorous shark ever known, Megalodon, was a member). The idea that mako sharks are white shark ancestors has gaine
d
considerable support from this extremely well-preserved new species -
often with shark fossils only isolated teeth are found, but in this case
we have a complete set of jaws (with 222 teeth) and 45 vertebrae.
The teeth of this fossil shark, named Carcharodon hubbelli, show both white and mako shark characteristics. They have a white shark-like shape and similar coarse serrations, but they also have features of mako sharks (such as the third anterior tooth being curved out). It certainly seems to be a gradation between the broad-toothed makos and today's white sharks.
These characteristics had been spotted when the fossil was first found, but its age had been estimated inaccurately at 4.5 million years old - too late to be a white shark ancestor. After researchers revisited the dig site and found mollusc shells, they calculated its true age as 6.5 million years old. This new age put C. hubbelli at the appropriate time to be a white shark ancestor.
Though this supports the mako ancestor theory, team leader Dana Ehret (Monmouth University, New Jersey) is not so sure we've heard the last of megatooth ancestry. "Some people might jump to the conclusion that this is a smoking gun, that the debate is over," Ehret said. "I don't think the debate will be over... While I personally think we make a very strong case that white sharks evolved from mako shark ancestors, I know some people out there will continue to investigate the relationships between the giant shark Megaladon and modern white sharks. That's how science has to work: You have to put out hypotheses and also test them, see if they stand up to scientific research."
Photo credit: Florida Museum of Natural History photo by Jeff Gage.
http://www.bbc.co.uk/news/
http://www.sciencedaily.com/
http://www.livescience.com/
The teeth of this fossil shark, named Carcharodon hubbelli, show both white and mako shark characteristics. They have a white shark-like shape and similar coarse serrations, but they also have features of mako sharks (such as the third anterior tooth being curved out). It certainly seems to be a gradation between the broad-toothed makos and today's white sharks.
These characteristics had been spotted when the fossil was first found, but its age had been estimated inaccurately at 4.5 million years old - too late to be a white shark ancestor. After researchers revisited the dig site and found mollusc shells, they calculated its true age as 6.5 million years old. This new age put C. hubbelli at the appropriate time to be a white shark ancestor.
Though this supports the mako ancestor theory, team leader Dana Ehret (Monmouth University, New Jersey) is not so sure we've heard the last of megatooth ancestry. "Some people might jump to the conclusion that this is a smoking gun, that the debate is over," Ehret said. "I don't think the debate will be over... While I personally think we make a very strong case that white sharks evolved from mako shark ancestors, I know some people out there will continue to investigate the relationships between the giant shark Megaladon and modern white sharks. That's how science has to work: You have to put out hypotheses and also test them, see if they stand up to scientific research."
Photo credit: Florida Museum of Natural History photo by Jeff Gage.
http://www.bbc.co.uk/news/
http://www.sciencedaily.com/
http://www.livescience.com/
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