Aidan Martin of ReefQuest explains the evolution of sharks. Sharks are one of the oldest creatures, preceding dinosaurs by about 200 million years according to Martin. Often fossilized shark teeth, and scales must be used to study the evolution of sharks because sharks do not leave behind bones to study, which makes it extremely difficult for researchers to determine much about these prehistoric sharks. The earliest sharks date back to 420 million years ago, based off of scales found in Siberia. Not much is known about sharks from this time period. Yet, Martin states, “Fortunately, the shark fossil record becomes richer and more varied from the Devonian Period onward”. The earliest evidence of sharks from the Devonian Period dates back to 400 million years, located in modern day Europe. These sharks, known as Leonodus, are thought to be from a group of freshwater sharks based on their teeth shape and size. As a group sharks exhibited their remarkable adaptability by surviving many environmental pressures such as changes in sea level, and ocean circulation. Martin goes on to say, “Each time their environment was radically altered, shark lineages responded with a spectacular flowering of diversity, enabling them
Aidan Martin of ReefQuest explains the evolution of sharks. Sharks are one of the oldest creatures, preceding dinosaurs by about 200 million years according to Martin. Often fossilized shark teeth, and scales must be used to study the evolution of sharks because sharks do not leave behind bones to study, which makes it extremely difficult for researchers to determine much about these prehistoric sharks. The earliest sharks date back to 420 million years ago, based off of scales found in Siberia. Not much is known about sharks from this time period. Yet, Martin states, “Fortunately, the shark fossil record becomes richer and more varied from the Devonian Period onward”. The earliest evidence of sharks from the Devonian Period dates back to 400 million years, located in modern day Europe. These sharks, known as Leonodus, are thought to be from a group of freshwater sharks based on their teeth shape and size. As a group sharks exhibited their remarkable adaptability by surviving many environmental pressures such as changes in sea level, and ocean circulation. Martin goes on to say, “Each time their environment was radically altered, shark lineages responded with a spectacular flowering of diversity, enabling them