The Ancient Jeffersonians (also known as Paleo-Jeffersonians and Jeffersites) were an intelligent species which inhabited the planet Jefferson approximately 52 million years ago. They are known primarily from the preserved ruins of their industrial civilization, which reached a digital-age level of technology before collapsing due to unclear reasons. Their prior presence was recognized shortly after human colonization of the planet began. Little evidence remains of the ancient Jeffersonians themselves beyond a few bones and clothing items. By itself this is not surprising, fossilization is rare enough that entire species may be absent from the geological record, but the paucity of artificial representations such as statues or carvings remains puzzling, as does the absence of organized grave sites. Thus, some scientists theorize most of them had a taboo, perhaps biologically-ingrained, against artificial depictions of themselves, and laid their dead to rest in ways suboptimal for preservation, such as cremation or exposure to the elements. Other xenologists have criticized this on the grounds that no extant species displays similar traits.