This is the third mission in the story.
In the first part, you will be tasked to build some buildings. Easy.
Next you need to move 6 stegosauruses to their own pen. This means using a tranq gun with a ranger vehicle manually. Drive down to where they are at and stay far back. You will need to aim high to hit them, but take your time. Other dinos can bump into you and knock off 1%, so stay back and keep a save file before you go down to where they are at just in case.
The third part has you take pictures and tranq the stegos again. I took my ranger cars up to the pen (don't go in) and just shoot at them until they are all down.
The last part has you make a cure and then you will need to tranq them while they sleep.
Note: When done, put both rangers in the pen or a pen close by with no door and trap them close to the dinosaurs. Have one get a camera out (outside away from the dinos if that helps) and take a photo of one getting attacked for this achievement: