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Extinction of megasharks

Extinction of megasharks. By: Harley Lewis. Main question?. What happened to megasharks like Carcharodon megalodon?. Difficulties of study. Cartilage skeleton No more around Just teeth to go by. Multiple theories. Theory #1 Temperature based growth Theory #2

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Extinction of megasharks

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  1. Extinction of megasharks By: Harley Lewis

  2. Main question? • What happened to megasharks like Carcharodon megalodon?

  3. Difficulties of study • Cartilage skeleton • No more around • Just teeth to go by

  4. Multiple theories • Theory #1 • Temperature based growth • Theory #2 • Diet reduction/ outcompeted • Theory #3 • Evolved into Great White

  5. Theory #1: Temperature based growth • Sharks are Ectothermic • Lower temperatures = slow growth, greater size • Miocene plagued by ice ages

  6. Correlation of growth rate and temperature Angilletta M J et al. Integr. Comp. Biol. 2004;44:498-509 The Society for Integrative and Comparative Biology

  7. Theory #2: Diet reduction / outcompeted • Cetaceans were main foodsource of Megalodon • Whales hit diversity peak during the Miocene • Diversity began to decrease to smaller species

  8. Theory #3: Evolved to Great Whites • Teeth and jaws look similar • Not true! • Shape and Roots are more like extinct makos than Megalodon • Low, flat root tube • Great White serration most likely came later

  9. Conclusions • Miocene ice ages contributed to great size • Cetacean diversity plummeted • Megalodon did not evolve into Great Whites

  10. References • Bright, M. (n.d.). Jaws: the natual history of sharks. Retrieved from http://www.fathom.com/course/21701777/session3.html • Bruner, John Clay. 1997. The "Megatooth" shark, Carcharodon megalodon "Rough toothed, huge toothed". Mundo Marino Revista Internacional de Vida Marina. September - October 1997(5):6-11. • Uhen, Mark D., and Pyenson, Nicholas D., 2007. Diversity estimates, biases, and historiographic effects: resolving cetacean diversity in the Tertiary. Palaeontologia Electronica Vol. 10, Issue 2; 11A:22p, 754KB; http://palaeo-electronica.org/paleo/2007_2/00123/index.html • Pimiento C, Ehret DJ, MacFadden BJ, Hubbell G, 2010 Ancient Nursery Area for the Extinct Giant Shark Megalodon from the Miocene of Panama. PLoS ONE 5(5): http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0010552 • Angilletta, M, Steury, T, & Sears, M. (2010). Temperature, growth rate, and body size in ectotherms: fitting pieces of a life-history puzzle. Integrative and Comparative Biology, 44(6), 498-509.

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