Vivosaurs are creatures that are revived from the fossils of prehistoric animals. Because the fossils are influenced over time by their environments, many vivosaurs have powers and physical features their animal counterparts did not originally have. Once revived, vivosaurs can take the form of Dino Medals, small, portable objects that can easily be carried and stored. Vivosaurs are primarily used by people known as Fossil Fighters to compete in Fossil Battles, although some act as companions or even as modes of transportation.
Vivosaurs can be one of six Elements (also referred to as "types"): Fire, Water, Earth, Air, Neutral, and the rare Legendary Element. A vivosaur's Element gives it special elemental powers and affects how much damage it deals to and receives from vivosaurs of different Elements. With the exception of the Neutral and Legendary Elements, each Element is strong against one Element and weak to another.