Though the term "time doorway" is used throughout the series, Land of the Lost is not meant to portray an era in Earth's history, but rather an enigmatic zone whose place and time are unknown. Indeed, within the first few minutes of the pilot, the Marshall family father tells his children that he spotted three moons in the sky. The original creators of these time portals were thought to be the ancestors of the Sleestak, called Altrusians, though later episodes raised some questions about this.
Though the term "time doorway" is used throughout the series, Land of the Lost is not meant to portray an era in Earth's history but rather an enigmatic zone whose place and time are unknown. Indeed, within the first few minutes of the pilot, the Marshall family father tells his children that he spotted three moons in the sky. The original creators of these time portals were thought to be the ancestors of the Sleestak, called Altrusians, though later episodes raised some questions about this.