In a remote part of Nevada, bones of giant prehistoric swimming reptiles harken back to when the arid region once sat on a coastline. Hundreds of miles away, in what is now Nebraska, volcanic ash buried more than 100 barrel-bodied rhinos some 12 million years ago. From Connecticut to Wyoming, dinosaur sites tantalize with clues of feeding frenzies and ancient trackways.

Many of the fossils excavated in the U.S. have been moved to urban museums, or at least to a nearby visitor center. But in some parts of the country, visitors can still see bones, tracks and other fossils where they've been unearthed, a fossilized snapshot dating from thousands to millions of years in the past. Even better, some of these spots feature paleontologists digging and dusting in the hunt for new specimens.

This slide show provides a visual sampler of excavation sites with fossils in situ, or left in their natural state. Frequently, the fossils are shielded from the weather and other elements by some kind of building or enclosure. Sometimes they are intact skeletons; other times they are scattered bones. Be sure to scout ahead before getting in the car, as accessibility may vary depending on the time of year.

View Slide Show of Paleontologists Digging Up Fossils