Paleontologists in France recently unearthed a giant dinosaur thigh bone from the late Jurassic period. The dinosaur femur dates back to over 140 million years ago. It's thought to belong to a sauropod. Sauropods were large herbivores with long necks and tails, relatives of the better-known diplodocus. They're among the largest land animals ever known. Paleontologists are especially impressed by how well-preserved this particular fossil is.