Sometime around 1920, Early Jurassic dinosaur tracks were discovered during renovations on the grounds of Oak Hill while sandstone was being excavated to line its terraces and walkways. Later, a scientific paper published in 1956 reported the presence of 17 species of nautiloid across 10 genera from a unit at the transition between the Cambrian and Ordovician in Virginia. Of the ten genera observed two were new to science. The researchers also observed that many of these were similar to their contemporaries in neighboring states. During the 1980s the Midland Fish bed was flooded in the course of the construction of a dam. This site preserved abundant remains of Early Jurassic fish like semionotids, palaeoniscids, and coelacanths. Prior to its inundation it had been regarded as one of the best sources of fish fossils in Virginia. In 1993, the scallop Chesapecten jeffersonius was designated the Virginia state fossil.
