Although the fossil record is, after all, set in stone, the, conclusions it supports remain remarkably fluid. For some time, the earliest vertebrate fossils known to paleontology came from the Ordovician period, 480 million years ago. Now that keystone event has been pushed back by some 50 million years. Paleontologists working in southern China recently discovered the fossilized remains of two fishes, both about 530 million years old, making them the most ancient vertebrate fossils known to science. The discovery calls into question exactly how long fishes have been swimming in the ocean.
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