When They Ruled the Earth Achievement

The dinosaur footprints are located at the Landmark "Frozen in Time" in Dinosaur Hill on the Silver Ridge Peaks map. The coordinates are roughly -1356, -10520. Below is a picture of the location on the reserve map.

Below is a picture of the footprints. The achievement should pop as soon as you take the picture in photo mode. I interacted with the landmark first, so i'm not sure if you have to do that first or not.