You can swim and step in the fossilized tracks of Acrocanthosaurus, a three-toed, two-legged carnosaur, or Pleurocoelus, a four-legged plant-eating sauropod, at Dinosaur Valley State Park, located near Glen Rose, 90 minutes from downtown Dallas. The fossilized tracks are found beside the Paluxy River, which winds through the park, and quite a few families have discovered that this is a great place to swim (in relatively clean water) and learn something about science at the same time. The river isn't particularly deep, and while a few spots are faster-flowing, all but the smallest kids can handle the current. The park also offers hiking trails, picnicking facilities and wildlife viewing.