For anyone still looking for the pteryx kills, I ended up on 33 kills from just following main storyline. There is a place that is not part of main quest called Nerotelos that has at least 15 in there, and it may help you mop up the remaining few.
Also, I can confirm that if your partner kills the pteryxs before you do in the quest to get the feathers, it will not credit you with a kill.
Originally Posted by Explicitlyy
I love when people call me a "hacker" because I'm better than them at the game. Like dude, come on, just get good.