Sharks’ teeth are falling! Sharks’ teeth are falling!
When I was a boy on vacation with my parents in Surfside Beach, South Carolina, I wondered how fossilized sharks’ teeth ended up ashore. I imagined that, perhaps, people were dropping them from planes near the coast, and that the teeth were carried by the surf to the beach. Hence, I thought, tourists would be more likely to return to the beach and spend their money.
Maybe not. Pliny the Elder, a Roman naturalist and philosopher, believed that fossilized sharks’ teeth fell from the heavens during eclipses of the moon. Pliny (aka Gaius Plinius Secundus) wrote a natural history encyclopedia. He was a pretty smart guy. Apparently, Pliny was a bad dude as well. He served as a Roman military commander.
Anyway. As I learned over the years, sharks’ teeth do fall. They fall from the mouths of sharks and drop to the ocean floor. If a tooth gets buried there quickly enough, it may very well become a fossil in 10,000 years or so. In a process known as permineralization, water seeps through the ocean floor into the minute pores of a tooth’s surface and forms a crystal cast with deposited minerals.
As the late marine biologist Rachel Carson explained in her great, 1950s book, The Sea Around Us, sharks’ teeth are part of a “stupendous snowfall” of materials that drift to the bottom of the sea.
The bulk of the “snowfall” is composed of lime and silica shells that once encased billions and billions of living sea creatures. River silt, coastal erosion, skeletal remains, glacial debris and meteoric fragments account for much of the rest. Over eons, the sediments accumulated on the ocean floor to thicknesses of over two miles.
“The sediments are a sort of epic poem of the earth,” Carson wrote. “When we are wise enough, perhaps we can read in them all of past history. For all is written here.”
The sea doesn’t give up her secrets easily, but the fossils we find on the beach reveal a little bit of the story. Using Carson’s analogy, fossilized sharks’ teeth divulge perhaps one word of the “epic poem.” Over the years, for example, I’ve found mako teeth with a few serrated edges and I’ve found mako teeth without any serration. Voila! Evolution.
Thank Sun God Ra for that endless snowfall of material. Without it, a shark’s tooth wouldn’t stand a chance of making it to the beach. And speaking of material..
Volcanic ash accounts for some of the stuff in which teeth get buried. Remember our buddy, Pliny. He died while nearing Mount Vesuvius as it erupted in 79 A.D. One would think that a natural history buff would know enough to keep his distance from lava, ash and toxic fumes.
Maybe Pliny was a few grapes short of a cluster. He believed, afterall, that sharks’ teeth fell from the heavens. Then again, so did I. Hmm..
My sediments, exactly.