At lvl 72 with flak armor on, a lvl 5 Troodon knocked me out with one attack at night. Last thing I saw was those glowing eyes before passing out. My Guess is that they attack vital organs. Luckily my Doedicarus was up for a game of baseball and launched that little devil out into the stands.
Those eyes, they haunt me even when its venom knocked me out, and is slowly picking off my pack of low-level Allosaurus. Now I have a Troodon... Yay... The Troodon was level 180. My pack of Allosaurus were around level 20. 6 Allosaurus died that evening.