Great Incident

The Great Incident was a paranormal event that caused a rift that brought Travis Jefferson High School and a few other areas 4 million years into the future, where many of the prehistoric animals of Earth's ancient past have suddenly returned from extinction, where the Sauroids have taken over as the dominant species, and where a number of mankind evolved separately into different races, including Dwarves,  Giants, and a few others. It is unknown how and why such a cataclysmic event had occurred, although it was responsible for profoundly affecting its "victims" in some way.