Emergence, Extinction of Massive Ancient Shark to be Explored with NSF Grant
Forty million years after dinosaurs went extinct, one of the largest predators that ever prowled Earthās oceans emerged, feeding the imaginations of modern scientists and the nightmares of modern movie audiences.
Megalodon ā the name means āgiant toothā ā appeared some 23 million years ago and reigned the seas for about 21 million years. In 400 million years of shark evolution, megalodon is the most massive shark species that ever lived, growing to 60 feet long, or three times the size of the largest of todayās great whites.
But megalodon went extinct about 2.5 million years ago, and Ā鶹ĪŽĀė°ę paleoecology Professor Sora Kim wants to know why.
Through a three-year project funded by a , Kim hopes to learn about the megalodonās diet, habitat and physiology and whether they played a role in the sharkās disappearance. Kimās team of co-investigators includes paleoclimatologist Michael Griffiths and environmental scientist Martin Becker, both from William Paterson University, paleobiologist Kenshu Shimada from DePaul University and marine scientist Robert Eagle from UCLA.
āThere are many ideas about why the megalodon went extinct,ā Kim said. āScientists have argued that changes in the megalodonās available prey base combined with climate change led to their demise. But these are just hypotheses. There have been no rigorous studies that demonstrate this conclusively.ā
What makes the megalodonās emergence, existence and ultimate extinction a mystery for the researchers is that the anatomy of these ancient sharks was much like that of modern sharks, with skeletons made of cartilage rather than bone. This feature ā also common to rays and skates ā distinguishes them from other vertebrates. But it means sharks donāt leave behind large fossilized remains like other animals with skeletons composed primarily of bone do. Bone is mineralized and fossilizes; cartilage doesnāt ā at least not well.
Luckily for Kim and her colleagues, thereās an exception to the rule: Just like modern sharks, megalodonās teeth were made of calcium phosphate, so the fossil record is replete with dental remains. Shark teeth are actually the most abundant vertebrate fossil, in part because a single shark sheds thousands of teeth in its lifetime, and the mineralized enameloid ā similar to the enamel on mammalsā teeth ā is extremely resistant to alteration.
Using fossilized teeth from different sites around the world that span megalodonās time as the oceanās apex predator, the researchers will use a suite of analytical methods not typically used in paleontology to probe them and improve understanding of the largest shark that ever swam Earthās oceans.
āIāll use stable isotope analysis and build a bridge between classical paleo and modern techniques,ā Kim said.
By performing āisotope fingerprintingā on oxygen, strontium, calcium and other trace elements found in fossilized megalodon teeth, Kim and colleagues will be able to answer fundamental questions about megalodon that have eluded scientists up to now.
āWhat did the meg eat? Could megalodon regulate its own body temperature? What was its environment like? And why did it go extinct? Isotope fingerprinting will provide more definitive answers to these questions,ā Kim said.
Kim is part of the with the . More than just an accomplished researcher, Kim is also a dedicated educator, and her new NSF grant reflects her interest in bringing science to undergraduates, especially those from groups underrepresented in science.
āWe need to bridge the gap between the undergraduate and graduate experience for underrepresented minorities who want to pursue science,ā Kim said. āThat means providing them with intensive mentoring and an authentic research experience.ā
As part of the grant, undergraduates from William Paterson University will have the opportunity to get hands-on research experience at Ā鶹ĪŽĀė°ę and Rutgers, attend scientific conferences and receive direct mentoring from Kim.
āĀ鶹ĪŽĀė°ę can provide a unique research experience for underrepresented minority undergraduates,ā Kim said. āThese students will come to campus and see students from similar backgrounds engaged in serious research. That can change what they think a research experience is supposed to look like.ā
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