Mountain fauna is something, unfortunately, left out of most of the fossil record. Due to the limits of the fossilization process, it is rare to find the prehistoric past of mountains. But there are a few examples, which are being uncovered more day by day about those creatures which lived in the mountains.

Link to the rest of my excellent music composer Dara Hughes’ work!
https://open.spotify.com/artist/5vzw5...

Wikipedia Articles for the topics if you want to learn more about them:
Green River Formation:https://en.wikipedia.org/wiki/Green_R...
Newark Supergroup: https://en.wikipedia.org/wiki/Newark_...
Wayan Formation: https://en.wikipedia.org/wiki/Wayan_F...
Oryctodromeus: https://en.wikipedia.org/wiki/Oryctod...



Sources Used:
https://www.americangeosciences.org/e...
https://www.sciencedirect.com/science...
Several other sources were used, but these were sent to me privately by Robert. If you really want them, I can work out a way to make the files available.