For the location of the fossil, it is in glittering cave which you'll have to go to when you get to Ambrette town. You'll get your first encounters with team flare in that cave also while you look for the scientist who will give you a choice of fossils. this is still before the 2nd gym and I believe you have to do it before you are allowed to progress to the town with the 2nd gym.
Reviving it is in the building that you were originally in when you were first sent to find the scientist.