"We now think that broad-toothed makos and fossil white sharks probably reached lengths upwards of 30 feet in the past, while the largest substantiated [living] white sharks are approximately 21 feet," Ehret said. As for megatooth sharks, the new study, published in the latest Journal of Vertebrate Paleontology, takes them out of the genus Carcharodon, which megatooths previously were thought to have shared with great whites, and places them in Carcharocles, a group with no known direct living representatives. "Ehret and his colleagues' work demonstrates a strong evolutionary link between the extinct mako (Isurus hastalis) and the modern great white shark (Carcharodon carcharias) and has concomitantly weakened the classic hypothesis that the modern great white shark evolved from the extinct megatooth shark," shark expert Kenshu Shimada told Discovery News. Shimada, an associate professor at DePaul University and a research associate in paleontology at the Sternberg Museum of Natural History, believes the genus Carcharocles belongs to the now-extinct family Otodontidae. "In order to settle the debate over the origin of the modern great white shark and the taxonomy of the megatooth shark, what we now need are the skeletal remains of the megatooth shark and otodontid sharks to examine their evolutionary link," he explained. Shimada indicated that if megatooths wind up being more closely related to otodontids versus modern great whites, the case can be more fully closed. "Regardless," he said, "Ehret and his colleagues' work is a very nice example of the provisional nature of science -- that is, scientific interpretations change as more data become available." Related Links: Jennifer Viegas' Blog: Born Animal Florida Museum of Natural History Ichthyology Department |
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