Mysteries at the Museum, always an enjoyable program, recently aired an episode about the Montana Mystery Beast. The huge, wolf-like animal was shot in 1883 after attacking cattle. It was so unusual that it was preserved by a taxidermist, and is now on display at the Madison Valley Historical Museum. Cryptozoologist Loren Coleman has suggested that it's a Shunka Warakin, a rare relative of the wolf immortalized in local Native American folklore.
Such a creature is mentioned in Hunt for the Skinwalker by Colm Kelleher and George Knapp. The story is that, just before the scientists who were going to study the famed Skinwalker Ranch for the Institute for Discovery Sciences arrived, a huge wolf came up out of a marsh and attacked some goats. The rancher shot at it, and right into it, with little effect. Finally, the animal went back into the marshy area.
The scientists tracked it and found that it's footprints went to the center of the marsh and simply disappeared. They took casts, and found that it must have weighed 300 pounds.
The Dire Wolf, which died out in the Pleistocene, weighed around 300 pounds. Could it still be around, or could animals, at times, pass between dimensions. If so, the one on display at the Madison Valley Museum didn't escape in time!