Dinosaur Valley State Park on the Paluxy River near Glen Rose preserves five main sites of theropod and sauropod footprints about 113 million years old, exposed in the riverbed by erosion through rocks of the Glen Rose Formation. First noticed in 1909 after a flood, the tracks gained wider importance around 1928 when R. T. Bird identified sauropod tracks here, cited as the first proof that sauropods walked on land. Texas acquired the land in 1968 and opened the park in 1972. Long valued for its fossil landscape, the area has also faced false claims of human tracks and, more recently, preservation concerns tied to nearby development proposals.