1. 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

9. 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

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

11. 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.htmlhttp://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 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.