To get 100% in all areas you must complete all hunts available and "Special Hunts" which consist of killing 20 - 40 Hyenas and Elands etc in addition to finding all fossils and vistas.
The Hunts and Vistas are easily found and marked on your map by driving around to clear the fog of war.
The fossils shimmer when encountered but gave me a little bit of trouble when searching for the last 2-3 on each level. Huge thanks to https://www.trueachievements.com/bongohawley.htm
for assisting in the last few. Screenshots below: