This last photo is of a Megalodon (prehistoric shark) tooth that I bought at a little rock shop between Zion and Bryce. The Megalodon was once believed to be the predecessor to the Great White, but due to differences in symmetry, (the Megalodon's teeth are mostly symmetrical and the Great White's aren't) it is now belived that they are from a different line. The Great White may have even existed at the same time as the Megalodon, at an estimated 15 million years ago.
