DICE really loves dinosaurs. It's no more apparent than with their final downloadable content pack for Battlefield 3, End Game. Users have already found a number of Easter Eggs, such as the pterodactyl that's flying around on the Nebandan Flats map above.
Other Easter Eggs include the dinosaur skull on the same map, snowmen on the Sabalan Pipeline map, and a little nod to Battlefield 2143 on Kharg Island. I wonder how many more Easter Eggs have yet to be discovered.