Shea It Ain't So

Sharks are older than trees, Saturn's rings, and the North Star. Sharks first appeared ~450M years ago, trees - 350M years ago, Saturn's rings - 100M years ago, and Polaris - 50M years ago. The earliest shark-like fishes appeared more than 400 million years ago, long before dinosaurs walked the Earth. Fossil evidence places their ancestors in the Silurian and Devonian periods, while the first forests did not develop until tens of millions of years later. Sharks have survived all five of Earth's major mass-extinction events, including the Permian extinction about 252 million years ago, which eliminated the majority of marine species. Their basic evolutionary strategy proved extraordinarily durable, although today's shark species are very different from their ancient ancestors. The comparison with Saturn is more complicated. Recent research suggests its spectacular rings may be only around 100 million years old, although their exact age remains debated. Sharks even predate the dinosaurs by roughly 150 million years. Dinosaurs first appeared about 230 million years ago, meaning sharks were already ancient by the time dinosaurs arrived. #drthehistories