Shark's teeth are a common fossil. Fossil teeth comprise much of the fossil record of the Elasmobranchii (shark). The most ancient types of sharks date back to 450 million years ago and are mostly known by their fossilized teeth. However, the commonly found fossil shark teeth are from the Cenozoic era (the last 66 million years).
Sharks lose about 35,000 teeth in their lifetime. A tooth becomes a fossil when it drops into sediment, then absorbs minerals from the surrounding sediment. Sediment prevents oxygen and harmful bacteria from reaching the tooth and destroying it. As the minerals replace the natural structure of the tooth, the tooth becomes the same general color as the sediment, usually black with a grayish crown. It takes about 10,000 years for a tooth to become a fossil.
C. megalodon teeth are the largest of any shark, extinct or living, and are among the most sought after types of shark teeth in the world. This shark lived during the late Oligocene epoch and Neogene period, roughly about 28 to 1.5 million years ago, and ranged to a maximum height of about 60 ft.The largest teeth are in excess of 7 inches long.
The State of Maryland has several excellent locations for finding fossil shark teeth including along the Potomac River and near the Calvert Cliffs by the Chesapeake. What does this tell us about the land in these locations?