On August 23, 1966, hundreds of dinosaur tracks were uncovered in Rocky Hill. The first few tracks were discovered by a bulldozer operator who was excavating the site for a new state building when his machine overturned a large slab of sandstone exposing the millions-of-years-old footprints. News of the discovery of the three-toed footprints quickly spread as more tracks were uncovered, and within a few weeks state officials made a decision to preserve the area as a state park. This quick thinking led to the immediate protection and preservation of the area and in turn, the park has one of the largest on-site displays of dinosaur tracks in the world. The site was named Dinosaur State Park and designated as a National Landmark in 1968.
The tracks found in Rocky Hill are from the early Jurassic period and were made more than 200 million years ago by a species of carnivorous dinosaur. There are presently 500 preserved tracks in a 55,000-square-foot area enclosed by a geodesic dome. Another 1,500 tracks have been buried for preservation purposes. The discovery of the footprints in Rocky Hill in the 1960s is far from the first trackway discovery in this area, however. In the 19th century, numerous specimens in the Connecticut Valley were uncovered in the heavily mined brownstone quarries and found their way into museums throughout the world.