Sharks have been around longer than trees.
Shark-like fish appear in the fossil record around 450 million years ago. The first true trees, such as Archaeopteris, showed up roughly 385 million years ago.
Why is this true?
Sharks also predate the rings of Saturn by most estimates and have survived all five mass extinctions. Their basic body plan has changed remarkably little because it works.
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More about animals
Animals are the easiest place to find facts that sound invented. Three hearts, blue blood, cube-shaped droppings, a punch fast enough to boil water for an instant — every one of these is ordinary biology to the animal doing it. The collection here leans on well-documented behaviour and anatomy rather than folklore, so each entry comes with a short explanation of why the trick actually works and a source you can read next.