During the story, you will move to Site B and start mission 3. This mission is called "Facility Recovery." You will want to make a save at the start of this mission (or after you build the starting buildings to save time if you need to reload). Follow this guide for getting another achievement first:
Once you have that unlocked, make a small pen and gate connected to the pen with the stegosauruses in it and drive your ranger in there and delete the gate. Drive another ranger into the stegosaurus pen and delete that gate. Park the ranger in a spot the other one can see it in and change over to it. With no gates, the cars will not move and you just need to wait with a camera out and take the picture when the car goes flying. Make an extra save when you are set up just in case you need it.