Not 100% sure, but I think that this is the first story based achievement in the game, that everyone should get.
In chapter 3 after clearing the neon-green egg underground area, you will get again into a forest world. Run past all the robots who march above you and hide to not get detected by the flying round robots. After that passage, you will enter a tree where you have to jump quite often. Do so until you are standing on an alien animal skull. Run further to the right and jump to a small plattform. A glowing flying animal will wake up and fly away.
Bingo, achievement "Bone Appetite!" unlocked.
For those who want a video solution, I found a full walkthrough on YouTube. So credit for the uploader "Virtual Conflux" for that video. The timestamp for this achievement is at 22:15 min.