Mastodonia, a science fiction novel by Clifford D. Simak, tells the story of a paleontologist who discovers an alien stranded on his Wisconsin farm. The alien, named Catface, can create time portals, leading to a prehistoric world the protagonist names "Mastodonia". The narrative explores the consequences of opening this prehistoric world to corporate greed and government intervention. 
 
Synopsis
The story follows Asa Steele, a paleontologist on sabbatical in rural Wisconsin. His dog, Bowser, brings home unusual artifacts and fresh dinosaur bones, which leads Asa to discover the crash-landed alien, Catface. Catface has been on Earth for 50,000 years and has created time tunnels to the distant past. 
 
Asa, his former lover Rila, and the alien Catface learn how to control and monetize these portals, which lead to a prehistoric era they dub "Mastodonia". They decide to turn this venture into a business centered around guided prehistoric safaris, but to avoid government oversight, they declare Mastodonia an independent nation. Their plan quickly goes awry as corporate and political interests, as well as religious fanatics, attempt to gain control of the time-travel technology for their own purposes.