Simple enough to get this achievement. Complete the level. But as of July 11th, 2015 when I posted this solution there is a glitch when playing splitscreen.
The first half of the level you play as Sarah Harding and Nick Van Owen saving the captured dinosaurs. There is a cut scene then you play as Ian Malcolm and Eddie Carr for the second half of the level where Eddie is at the top of the cliff edge while Ian climbs up a rope.
I personally have played this level 3 times in splitscreen and once solo.
Every time I played splitscreen when I reached the second half of the level Ian and Eddie were switched roles. Eddie had to climb while Ian was up top. This makes completing the level impossible in normal story mode. So don't play this level splitscreen in story mode unless you drop out one player before the cut scene. The level is just fine in free play since you can switch characters.
Update: Thanks to misschiefmaker for confirming the glitch. So I recommend playing this level solo in story mode. If you have a second profile that wants the achievement you can still obtain it in free play.