This is the 4th main storyline achievement of Episode 1 and is therefore unmissable. When you begin the game you will be in a rather small area and you will have to progress to a point where you need 3 animal tokens in order to progress. The 3 tokens are located at the following spots:
Quetzal: After using the metal bars and canvas to make a bridge across a gap use your knife near a pot.
Coiled Snake: At the very first screen turn left and look for a crevice. Use the torch to see inside for this piece.
Jaguar: This is the reward for solving the metal disk puzzle. Once you have all the disks put the first and third on the right side and all other disks go in the left side.
Now all that's left to do is put the tokens in the door. Once you've solved this puzzle this achievement will pop. Please refer to the excellent walkthrough created by DTI April here if you are still unclear.
Prior storyline achievement:
Next storyline achievement: