This list of the prehistoric life of Montana contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Montana.
Precambrian
The Paleobiology Database records no known occurrences of Precambrian fossils in Montana.
Mounted fossilized skeleton of the Pleistocene Bison latifrons, also known as the giant bison or long-horned bison †Bison latifrons – or unidentified comparable form