I was on a adventure and one of these turds came up and bit me. I just looked at it and shot it but my juicy beefed up Rex with amazing health, stamina and everything else went crazy since it was on neutral and it jumped off a cliff and I never found him. When I say I screamed for 1 hour straight, I mean it.
I nearly lost my Pteranodon to these things. They make you or your mount lose stamina, and that happened right by a freaking Tyrannosaurus. Luckily I killed them and got away. This same thing happened when I was taking home an Argentavis I tamed. These things attacked my Pteranodon, and I had to make an emergency landing in the Redwood Forest. I got away, luckily.