 Prehistoric species of various eras featured in the series include
"Agriochoerus",
"Alamosaurus",
"Archaeotherium",
"Brontops",
"Camptosaurus",
Columbian mammoth,
"Coryphodon",
"Deinosuchus",
"Diprotodon",
"Eurypterid",
"Gastornis" (called "Diatryma"),
"Gorgosaurus",
"Hoplophoneus",
"Hyaenodon",
"Ichthyostega",
Mastodon,
"Megalania",
"Merycoidodon",
"Metamynodon",
"Metoposaurus",
"Mylodon",
"Ornithomimus",
"Parasaurolophus",
"Phenacodus",
"Placerias",
"Postosuchus",
"Procoptodon",
"Rutiodon",
"Saurophaganax" or "Allosaurus" (referred to as "Epanterias"),
"Stegosaurus",
"Teratosaurus",
"Triceratops",
"Troodon formosus" (presented as "Stenonychosaurus", and supposedly a type of pachycephalosaur), and
"Tyrannosaurus trionychus".Tyrannosaurs of the genus "Gorgosaurus" are mentioned occasionally, and many times Reginald Rivers will say that the Raja is out in some period in the Cenozoic, taking a group to hunt some form of prehistoric mammal such as titanothere, entelodont, or uintathere.Prehistoric marsupials and Indricotherium are mentioned in "The Synthetic Barbarian," and numerous Pleistocene megafauna are seen in "The Mislaid Mastodon," including "Castoroides ohioensis" and the American lion.