Sturgeon like fishes appeared in the fossil record approximately 200 million years ago, around the very end of the Triassic, making them among the most ancient of actinopterygian fishes. True sturgeons appear in the fossil record during the Upper Cretaceous. In that time, sturgeons have undergone remarkably little change, indicating their evolution has been exceptionally slow and earning them an informal status as living fossils. But a new study by University of Michigan researchers and their colleagues reveals that in at least one measure of evolutionary change—changes in body size over time—sturgeon have been one of the fastest-evolving fish on the planet.