Trees first appeared 400 million years ago, during the Devonian period. Sharks first may have appeared 450 million years ago, during the Late Ordovician period.
Scientists are still trying to figure out whether the 450-million-year-old ancient scales they discovered were from real sharks or a similar species.
"Shark-like scales from the Late Ordovician have been found, but no teeth," said Emma Bernard of the Natural History Museum in London, England. "If these were from sharks, it would suggest that the earliest forms could have been toothless. Scientists are still debating if these were true sharks or shark-like animals."
These ancient sharks would have looked completely different than the sharks we know today. The first group of sharks to resemble the sharks that we are familiar with came about around 380 million years ago.