Fossils are remnants of ancient plants and animals preserved in stone and provide evidence scientists use to reconstruct the history of life on earth. Some fossils are petrified remains such as bones or wood, while others are impressions or traces left by vanished creatures, including footprints that form a trackway. Fossil bones reveal specific details about an animal's size, shape, and anatomy, while fossil trackways show how an animal moved and behaved, preserving evidence of a way of life that bones alone cannot reveal. The tracks here include those of Pleurocoelus, a sauropod related to brontosaurs, which had big, flat hindfeet with four claws, small hoof-like forefeet without claws, peg-like teeth for grinding plant food, and could travel on land about 2.7 miles per hour, and those of Acrocanthosaurus, a two-footed carnosaur related to tyrannosaurs, which had feet with three clawed toes, razor-sharp teeth for cutting flesh, and could travel about 5 miles per hour.