I was sitting on a flyer on a cliff above the deinos, thought I was safe to wait for my moment to steal their eggs...had the biggest heart attack when one of them decided to climb up the cliff. I accidentally dismounted in shock and fell right into the packs claws, where they shredded me to death. Don't be scared of them, they smell it.
These guys are idiots. Many of them spawn on clifftops. Just bring in a flyer (Argies or Pteranadons will do just fine) and take a swipe at them. They will all zero in on you instantly. Kite them right off a cliff. Do a smug slow-walk as you claim the eggs in complete safety.