Hi @acurrier, many would argue that gars are living fossils. There was actually a book published on living fossils, with a chapter dedicated to Lepisosteida, which is the family to which gars belong to. I’ve included the link below: http://link.springer.com/chapter/10.1007%2F978-1-4613-8271-3_17
I would be fantastic if you could upload pictures of the gar scales you found in Montana! I’d love to compare the two localities!